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Glossary of Terms

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An illustrated roof glossary.

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Glossary sorted by category,
Types of roofs | Roof Features | Roof Framing | Roof Trusses | Roof Coverings
Glossary alphabetically sorted
0-9  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z    "  


A
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Aisled Barn
A type of roof truss construction that has aisles down the side to increase the span;
Anti ponding strip
In roofing, tiles and slating. A flat strip of metal flashing material fixed to the top o the fascia and to the rafters to stop the sarking sagging so that no water can pond inside the fascia.;
Apron Flashing
A flashing that seals the top edge of a roof against a wall or chimney etc.;
Arcade post
A post at the side of a cruck truss to share the load and shorten the span. Usually seen in pairs in aisle barn construction.;
Arched brace
A curved brace, normally out of naturally curved timbers used to stiffen a roof frame. Usually in pairs.;
Asbestos containing roofing
Any roofing material containing asbestos fibres. Typically produced in corrugated sheets, imitation slates or imitation shingles. Banned as a new construction material since around 2000 in most countries.;
Ashlar piece
Inside roof spaces, lofts and garrets, the short vertical pieces fixed between the floor and the rafters to form short walls. (Not to be confused with ashlar masonry).;
Ashlaring
The short side wall frames in lofts, attics, garrets etc.;
B
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Barge or Verge Flashing
A flashing that seals the end of a roof against the verge or gable end.;
Bargeboard
A board or roll formed metal section fixed at the gable to finish and protect the roof to gable wall joint. ;
Barrel roof
A roof with a semi-circular cross section;
Base cruck
The cruck blades sit at ground level and rase to be joined to a tie or collar beam.;
Belfast truss
A roof truss that has the top chord in the form of a circular or sometimes a parabolic arc. Known to be economical over large spans.;
Belgian truss
Similar to a W truss or a Warren truss for longer spans with extra webs added. Also called a double Fink truss;
Birdsmouth
A timber joint,a notch cut out of an angled piece to let it sit on a cross member. Typically in a rafter at the wall plate or at a underpurlin.;
Bowstring truss
A roof truss that has the top chord in the form of a circular or sometimes a parabolic arc. Know to be economical over large spans.;
Box gutter
A horizontal gutter at the intersection of two parallel roof surfaces.;
Boxed Eaves
An eaves that has been lined with the lining material level, rather than following the slope of the roof.;
Butterfly roof
A roof that could be called an inverted gable roof. Both surfaces slope inwards from the walls to a central valley. ;
Buttress
A mass of masonry bonded to an exterior wall. Usually to stiffen it against the lateral thrust of roof structures.;
C
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C or cee purlins.
Cold rolled sections in the form of a letter "C". Used not only for roofs but for wall girts and they are used by shed manufactures to form columns, ties and braces. They are also used for floor joists. ;
Cambered Fink or Cambered Warren truss
A Fink or Warren truss with a raised center bottom chord.;
Cantilever truss
A truss where one end is allowed to run over the support. Part of the truss is said to be a cantilever.;
Ceiling battens
Supported by and running at right angles to the ceiling-joists the battens typically timber or roll formed metal support the actual ceiling lining material.;
Ceiling joists
A wooden or steel beam supporting a a ceiling. ;
Cement tile roofing
A roofing tile made out of cement or concrete based products. Available in many shapes and sizes.;
Chimney cricket
A section of roof framing to divert rainwater around a chimney or short parapet. ;
Clerestorey window
A window in the upper part of a wall and sometimes the lower edge of the roof to give light and ventilation to a high room.;
Collar Flashing
Any type of flashing that seals an object that passes through a roof. In particular now associated with proprietary fittings to suit various circular holes in roofs. i.e. vent pipes or extractor pipes.;
Collar tie
In timber roofs a member which spans two opposite rafters, usually at mid span between the wall plate and the ridge to stop the rafters spreading under load.;
Collar tie roof
A short span roof without a ceiling joist or other tie at the wall plates. A collar tie is used to create greater head height. ;
Common rafter
A roofing timber that defines the slope of a roof. It is set at right angles to the wall plate and rises to the ridge board. ;
Compass roof.
A pitched roof that has slight convex curves to the top surfaces. Depending on the amount of curve and the ratio of width to height they can range from almost a semicircle to a gothic arch. ;
Copper roofing
Flat sheets of copper used as a roofing material. Very long lasting. The typical green colour of an old copper roof is a layer of oxidisation that protects the material from further deterioration.;
Corrugated iron
A roll formed flat sheet roofing product that when formed with the ridges and valleys becomes stiff and strong. Called iron because it was first made out of wrought iron.;
Counter batten
A batten laid in the opposite direction to tile and slate battens fixed to the rafters. Usually nailed over a boarded and felted roof to provide a space to stop water ponding at the normal battens.;
Couple close roof
A short span roof with ceiling joists as ties but no other roof ties.;
Couple roof
A short span roof without a ceiling joist or other tie. The simplest of any ridged roof.;
Cripple rafter, Creeper rafter
A short rafter connecting a hip rafter and a valley rafter.;
Cruck blade
A single piece of timber when paired with another similar piece becomes a full cruck frame.;
Cruck construction
A category of medieval architecture of unsure origin where the main load bearing members are crucks. Large section naturally bent timbers that reach from the height of the roof to the floors. Later they extended to low side walls. ;
Cruck Truss
1.) One of a pair or naturally curved timbers used to form frames or trusses that were the main structural elements in medieval building in Northern Europe.
2.) A building that contains crucks or built using crucks.;
Curb
Curb is a name for the joint between the roof faces in gambrel and mansard roofs.;
D
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Dendrochronology
In old timber framed buildings it is used to date the time that trees were felled, and so the construction date, by various methods including study of the annual growth rings and carbon dating.;
Dendrology
The branch of botany involving the study of trees and shrubs. ;
Dormer window
A vertical window placed in a sloping roof. ;
Dutch gable
A lower part of a roof end that has a hip with an upper section with a gable. ;
E
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Eaves
The lower part of a sloping roof, the part of a roof which overhangs the walls. ;
Eaves brace
A brace between a wall and the eaves to increase the overhang at the eaves.;
Eaves bracket
A bracket between a wall and the eaves to increase the overhang at the eaves.;
Eaves lining
A sheeting or lining material to seal the underside of an overhanging eaves or verge. ;
Eaves Vents
A series openings in the eaves to facilitate the movement of air inside a roof space.;
Eltham Palace Roof
The third largest example of a hammer beam roof in the UK, built to cover the great hall of the palace built for Edward 1V in the 15th century south of London.;
End Lap
(In Roofing) The amount by which roofing tiles, slates shingles flashings etc overlap each other to achieve waterproofing at the end, that is in the direction of the slope. Higher overlaps lower by the amount of end lap.;
Eyebrow
A low dormer type projection in a roof surface with no side walls. The roof surface flows over it in a curve.;
F
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Fabric roofs
Roofs made from flexible membranes and tensioned cables. From simple shade structures to complex permanent structures.;
Fan truss
Similar to a W truss but with extra vertical ties added. Said that each sides web radiate like a fan.;
Fascia board
A horizontal board or roll formed metal fitting usually fixed vertically to the ends of the rafters ;
Fascia gutter
1.) A rainwater gutter that is fixed to a fascia board.
2.) A purpose made rainwater gutter that is fixed to the ends of the rafters and also performs the function of a fascia board.;
Fascia purlin
Usually in steel shed roofs, a rolled formed comnination of a fascia and a purlin. Can be ordred to suit varying roof pitches.;
Fascia stiffener
In an overhanging eaves, a horizontal timber behind the fascia at the hip corners to support the last jack rafters. ;
Finial
1.)In architecture, a pure decoration or embellishment to the high points of a building.
2.) The top, round cap to flagpoles.
3.) Non construction related - Probably the most use it gets today is in the soft furnishing sections of stores, it is a name for the moulded caps to curtain rail ends.;
Flashing
A strip of sleeve of impervious material, or a non-ferrous metal or coated steel material that is formed to stop the entry of water.;
Fly brace
A brace from the bottom flange of a rafter to a roof purlin that restrains the rafter laterally. ;
French truss
A roof truss based on two Howe trusses and a bottom chord. A way of making a larger truss out of prefabricated elements of smaller trusses, ;
Full Cruck
A cruck frame which reaches from the ridge to the floor using none jointed blades.;
G
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Gable
The vertical triangular end of a pitched roof. It often is a continuation of the wall it is sat on or it can be made from different materials.;
Gable dormer
A vertical window placed in a sloping gable roof. ;
Gable roofs
A roof with two sloping surfaces from the ridge (usually in the center, joining at the side walls to form gable ends. ;
Gable Vent
A louvred vent in a gable wall.;
Gablet
1). A small gable that projects from another roof surface, similar to a dormer but with no walls. It can indeed be sat at the top of a gable end but the term is rarely used in this respect any more. 2). A triangular coping to a wall or buttress.;
Galleria Roof
From the Italian word for gallery. The term is now loosely used to mean a roof over and between existing building to create a roofed public leisure and shopping space.;
Gambrel roof.
The gambrel has two slopes to each long side, the lower slope being much steeper. To better accommodate rooms inside the roof. A gambrel has gable walls on the shorter side.;
Gang nail truss
One of a series of trusses made with light timber sections joined together with metal nail plates.;
Girder truss
A roof truss that acts a truss, but at the same time is built stronger than a standard truss of the same span to carry extra loads imposed on it. Used in nailplate truss construction. Sometimes consists of two or more standard trusses fixed together.;
Gutter outlet
1.) An outlet for a gutter in a wall or parapet to allow water to drain off a roof. ;
Gutter overflow
An extra gutter outlet or scupper at a higher level than the normal outlet. To safely direct the water outside if the main outlet gets blocked or is overloaded.;
H
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Half truss
Used in shed type roofs and lean to roofs, it is in effect half of a normal truss with a vertical member to complete the triangle.;
Hammer Beam
Short horizontal beams built into and braced off the walls to help create larger open spans than would otherwise be possible with the means available at the time.;
Hammer Beam Truss
The ultimate development of timber roof truss design before the advent of modern materials, the hammer beam truss uses hammer beams extending a short way out from the walls to create an open and usually a highly decorative effect. The hammer beam roof is a peculiarly English creation with the finest example being in Westminster Hall.;
Hammer Post
A vertical post from the open end of the hammer beam to the principal rafter.;
Hampton Court Palace Roof
The second largest example of a hammer beam roof in the UK, built to cover the great hall of Henry V111's Tudor Palace at Hampton Court on the banks of the Thames near London, UK ;
Hanging beam
A beam that is on top of the members that it is supporting. Typically used in ceilings where a conventional beam would look unsightly or would reduce limited head height. ;
Helm Roof
A roof usually to a rectangular tower that has four gables with the ridges riseing from the gables to give the effect of a sharpened stake. Used on steeples.;
Hip
The meeting of two inclined roof surfaces.;
Hip flashing
The PM flashing of a hip to a roof sheeted with roll formed steel roofing.;
Hip rafter
An inclined board immediately under the junction of two roof surfaces, the hip. To which are fixed the jack rafters. It runs from the corner of the wall plates up to the ridge.;
Hip roof
A roof where the end surfaces also slope.;
Hip truss
One of a series of trusses made with light timber sections joined together with metal nail plates that sits in the hip position.;
Hipped gable
A roof that has a hipped end truncating a gable.;
Howe girder
A girder or truss with horizontal chords and the diagonal members pointing down and towards the supports.;
Howe truss
A roof truss with vertical web members to take tension forces and with angled braces to take compression;
I
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Imbrex and Tegula
Two Latin words that together describe a system of terra cotta roofing tiles that go back to Ancient Greek and Roman Tiles. The Tegula is a flat pan with raised sides. The Imbrex is a semi-circular tile that caps the joint between the Tegulae.;
Iron Roof Truss
A roof truss made out of either wrought iron, cast iron or more likely a combination or the two. Capable of large spans and often highly decorated.;
J
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Jack joists
Short joists at hip ends of hip roofs, running at right angles to the main ceiling-joists;
Jack rafter
A rafter that follows the same line as the common rafters, but it meets a hip instead of the ridge board. As a result it is shorter than the common rafters and has an inclined side or cheek cut where it meets the hip rafter. ;
Jack truss
Used in nail plate truss construction, a subsidiary truss that is fixed to a truncated truss with it's top chord flying over to reach the hip. Where not fixed to a truncated truss it is fixed to a hip truss.;
Jointed cruck
A cruck with joints to the main members. To extend the length of the timbers or alter the shapes.;
K
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King post truss
A roof truss mostly wooden with two principal rafters, a tie beam and a central vertical King post. The simplest of trusses. Mainly used with two angled struts.;
Knee brace
A brace between a post and beam, the bottom chord of a roof truss and the support, or a stiffener in a portal frame.;
L
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Lap
(In Roofing) The amount by which roofing tiles, slates shingles flashings etc overlap each other to achieve waterproofing. Usally referred to as either Side Lap or End lap.;
Lathe Hammer
Universal tool for fixing battens (prior to nail guns). Has an axe head for cutting battens, a hammer head for nailing them and a notch for drawing out bent nails.;
Lattice Roof
A barrel or arched roof formed of many small sections fixed together to form the roof structure. They have been made out of RC concrete, timber, aluminium and steel.;
Lead roofing
Flat sheets of lead used as a roofing material. Very long lasting. Used for flat roofs and pitched roofs (usually out of sight) and extremely usfull for flashings because of its malleability.;
Lean to roof
A single pitch roof. The lean to is exactly what it says, the top end of it leans against another structure.;
Link dormer
A dormer that typically houses a chimney. Also used to join one part of a roof to another ;
M
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Mansard roof
A roof that has two slopes to each side, the lower slope being much steeper. To better accommodate rooms inside the roof. ;
Mediterranean clay tiles
Also known as barrel or mission tiles in the US these semicircular with a taper are laid in alternate concave and convex rows.;
Metal ceiling battens
Made out of roll formed metal. similar but smaller in profile the roof-battens. Tek screwed to the ceiling joists, more often used in conjunction with gang nail truss construction.;
Metal Roof battens
Made out of roll formed metal. In a type of "top hat" section. Tek screwed to the rafters.;
Moisture barrier
Any material sheet of membrane that prevents the undesirable flow of moisture into a building structure or for the control of condensation and water vapour.;
Monitor roof
A raised extension above a ridge that can provide light and ventilation to the room below. ;
Monospace truss
Used in shed type roofs and lean to roofs, it is in effect half of a normal truss with a vertical member to complete the triangle. The strut and web pattern is the same as a W truss.;
O
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Ogee roof
A curved roof based on the "ogee" curve.;
P
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Pantile
In the UK the name of traditional type of terra cotta or clay tile. "The Pantiles" is the name of an area in the town of Tunbridge wells, Kent, UK.;
Parapet
1.) The part of an exterior wall, gable or party wall that is entirely above the roof surface
2.) A low wall to guard the edge of a drop off. 3.) A defense wall.;
Parapet gutter
A gutter at the intersection of a parapet wall and the bottom of a roof slope.;
Pavilion roof
Usually a roof set on a regular polygon with equal hips on all sides. ;
Pendant
A suspended feature in gothic architecture, used in stone vaults and timber roofs. Also called a pendent. ;
Penetration flashing
Any type of flashing that seals an object that passes through a roof. In particular now associated with proprietary fittings to suit various circular holes in roofs. i.e. vent pipes or extractor pipes.;
Plastic roofing
Roofing material made for patios and decks etc. to allow varying amounts of light through the sheeting. Made from synthetic materials, fiberglass, polycarbonate etc.;
PM flashing
"Pressed metal" material usually 0.9mm thick in the same finish as the roofing. It is cut to length and width in a guillotine and then shaped in a brake press. The lengths of the individual flashings are governed by the size of the machine available. 6M. is common.;
Pole Plate
A horizontal member, steel or timber, fixed to the face of a wall to which roof framing is fixed. Typically rafters in a lean to type of roof.;
Polygonal roof
Usually a roof set on a regular polygon with equal hips on all sides. It is seen a a decorative roof used in gardens and parks. ;
Pratt girder
A girder or truss with horizontal chords and the diagonal members pointing down and towards the center. ;
Pratt truss
A truss with alternate vertical and angled members between the chords. They angled members pointing down and towards the center.;
Principal rafter
One of the main diagonal members in in a roof truss on which the purlins sit, which in turn support the common rafters. ;
purlin
1.) A horizontal roof member, steel or timber, sitting on the principal rafter of a truss or propped off a wall to support the rafters. AKA Under purlin.
2.) A horizontal roof member sitting on the rafters or on a truss or steel member that the roofing material is directly fixed to. AKA over purlin.;
Purlin bolts
Nut and bolt sets specifically designed for fixing cold rolled steel purlins. The bolt and nut heads have the washer with a serrated gripping surface formed integrally.;
Purlin bridging
Lightweight roll formed metal channel sections with proprietary end fittings used to stiffen Cee and Zed purlins;
Purlin cleat
1.) Steel, a MS plate or angle punched to a set pattern of holes or slots to suit a particular size of steel purlins. Either welded or bolted to the support member.
2.) Timber, a short piece of timber fixed to a support member to hold timber purlins in position.;
Q
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Queen post truss
A roof truss mostly wooden with two principal rafters and two vertical Queen posts with a restraining tie beam at the bottom and a straining beam at the top.;
R
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Rainbow roof
A pitched roof that has slight convex cruves to the top surfaces ;
Rainwater head
A funnel or boxlike head at the top of a down pipe or downspout for the collection of rainwater from a gutter outlet or overflow. Also know as:-rainwater header, rainwater sump, leader head, conductor head.;
Raised cruck
A cruck truss that is raised to sit on usually short walls. Either masonry or timber.;
Reducing truss
One of a set of nailplate roof trusses that sit on the backs of other trusses to form valleys.;
RHS purlins
Rectangular Hollow Section. Often used as purlins on roof to decks and verandahs, where the structure is exposed to view. Usually the wall thickness used is 2.0mm or 2.5mm. Should always have welded end caps to seal the inside from corrosion.;
Ridge
The apex of a roof. The highest point. Usually where two roof surface are parallel then the ridge is a horizontal intersection of the two.;
Ridge board
A horizontal board immediately under the ridge of the roof to which the tops of the rafters are fixed.;
Ridge Vent
A horizontal vent to remove hot air etc. fixed to the ridge of a peaked roof.;
Roof battens
Horizontal members fixed to the top of the rafters the battens vary in size and spacing depending on the roof material that they carry. In the larger sizes sometimes called purlins.;
Roof framing
The total of the structural roof members which when connected form the support for the roof coverings;
Roof Vents
A series openings in a sealed roof to ventilate the roof space.;
Roof verge
The edge of a gable roof at the gable wall. Sometimes flush with the wall and often has an overhang. ;
Roofing felt, Underlay
A pliable water resistant membrane used beneath roofing and wall sheeting to collect and discharge any water or condensation. Usually combined with reflective foil and sometimes materials to give thermal insulation benefits. Also know as sarking.;
Roofing nail
Galvanised nails for fixing corrugated iron. About 65mm long with an integral washer they are now superseded by roofing screws.;
Rotary Vent
A rotary spinning extractor vent, driven by wind power only, or by electric motor. Usually fixed towards the ridge of a peaked roof.;
S
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Sailover truss
A truss where each end cantilevers over the support. Used to get extra height at the wall plate or to simplify boxing in the eaves. ;
Sarking
A pliable water resistant membrane used beneath roofing and wall sheeting to collect and discharge any water or condensation. Usually combined with reflective foil and sometimes materials to give thermal insulation benefits. Also know as roofing underlay or underlayment and roofing felt.;
Scissor truss
A truss with both the top chords and the bottom chords sloping upwards. To give a greater ceiling or clearance height.;
Scotch valley, Blind valley, California valley
A method of constructing a variation to a rectangular plan without the use of valley rafters. The method that all Multinail roof truss manufactures use. Far stronger than a traditional framed valley but requires a beam across the walls. ;
Scupper
1.) An outlet for a gutter in a wall or parapet to allow water to drain off a roof.
2.) A grill or other device to stop debris clogging a drain or gutter outlet.;
Shed dormer
A vertical window placed in a sloping shed roof. ;
Shed roof
A roof that has only one slope. It is normally sat on two parallel walls that have different heights. The difference in height being the fall or pitch or the roof. ;
Shingle clay tiles
Flat or slightly curved terracotta tiles fixed with similar laps and gauges to wood shingles or slates.;
Side Lap
(In Roofing) The amount by which roofing tiles, slates shingles flashings etc overlap each other to achieve waterproofing at the side, that is in a horizontal direction.;
Skillion roof
An Australian term for the same single slope roof, although it is often also applied to the lean to roof also.;
Slate and a half
A wider than normal slate used at the side where otherwise the cut piece would be less than a half.;
Slate axe, (ax), sax
A slater's axe, has a point at the back of the head for making nail holes in the slate. For cutting slates. ;
Slate batten, Slate lathe
Horizontal strips of timber laid on top of the common rafters or on counter battens to which the slates are fixed.;
Slate gauge
The spacing of the roofing battens;
Slate margin
The amount of slate open to view.;
Slate ripper
A flat steel plate with notches on the end. Used in repairs to rip out the nails fixing broken tiles etc. German ripper has a nail pulling claw on hand end.;
Slate roofing
A roofing material consisting of overlapping layers of slate.;
Slate roofs
Roofing material made from natural slate. A sedimentary rock that has the ability to be split into thin layers.;
Slater's hammer.
A tool with a long sharp point for piercing the slate for nail holes and a hammer head for nailing,;
Sprocket-piece
1.) A piece at the foot of a rafter to incline last section of the roof towards the horizontal, to make sprocked eaves.
2.) An outrigger piece attached to the end rafters at the verge of a gable roof to create a gable overhang.;
Steel purlin
A horizontal roof member to which roofing is fixed. Mostly cold rolled galvanized steel but can be any steel section thin enough to be easily screwed to.;
Stepped Flashing
A flashing that seals the sloping edge of a roof against a masonry or brick wall.;
Straining beam
1.) In a truss a horizontal strut above the tie beam.
2.) In a queen post truss the horizontal strut between the ends of the queen posts.;
Straining sill
A horizontal member in a timber roof, typically fixed to a tie beam to resist the sidways thrust of struts.;
T
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Terra cotta tiles
One of the oldest of roofing materials, these tiles are made from hard fired clay in many different shapes and patterns.;
Tie beam
1.) A horizontal member in roof framing, fixed to the foot of rafters to stop them spreading.
2.) In truss construction, timber or steel, the bottom horizontal member. The bottom chord.;
Tie Rod Truss
A roof truss that uses tie rods for the members under tension, ties, and solid timber or metal for the compression members.;
Tile battens
In roofing they are the horizontal strips of timber nailed across the rafters to fix cement and clay tiles to.;
Tilt or tilting fillet, Cant strip
A extra piece of timber at the fascia to lift the bottom row of slates.;
Timber ceiling battens
Made out of timber. Fixed to the ceiling joists in the with serrated grip nails (mostly by by nail guns). ;
Timber purlin
A horizontal timber or lumber roof member that supports the common rafters, or horizontal roof member to which roofing is fixed, either on the rafters or on trusses etc. ;
Timber Roof-battens
Made out of timber. Fixed to the rafters in the smaller sizes for slates and tiles with serrated grip nails (mostly by by nail guns), and in the larger sizes by various plate connectors or straps.;
Tracery
Curved openwork shapes in stone or wood of typical Gothic designs in windows openings or decorative screens.;
Truncated truss
A standard truss that has been truncated or has had it's top cut off. Usually to allow jack trusses to pass over it in hip roof design. The term girder truss truss is commonly applied as these trusses ofter act as a girder supporting the minor trusses abutting it. ;
U
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Upper cruck
The upper blades are sat on a tie beam and raise up to the ridge. ;
V
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Valley
The meeting of two inclined roof surfaces at a re-entrant angle.;
Valley jack rafter
A short rafter connecting a ridge board and a valley rafter. ;
Valley rafter
The main support timber directly under the valley intersection of two roof surfaces. It corresponds to the hip rafter in terms of the same slope and roofing angles. It supports the valley jack rafters and any valley creepers. ;
Vergeboard
A board or roll formed metal section fixed at the gable to finish and protect the roof to gable wall joint.;
Vermin proofing
Protecting a building against the entry of rats and mice and other vermin. Particularly at the eaves. Usually by expanded metal mesh.;
W
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W truss
A triangular truss where the web members take the form of a W.;
Wall Plate
1.) A horizontal member, usually timber bolted or otherwise fixed to the top of a wall to which the roof framing is fixed.
2.) A horizontal member, such as a steel plate fixed to a masonry or concrete wall to carry the end of a beam or to attach a beam to other members.
3.) A horizontal member, either at the top or bottom of a wall frame. Known as top plates or bottom plates.
4.) A board fixed to a vertical surface of a wall to which shoring or props are fixed. Note! when used for the purpose of fixing rafters against a wall then it is known as a Pole Plate.;
Wall post
A vertical post against the wall under a hammer beam or tie beam and down to the corbel to secure the curved brace and help transmit roof loads to the corbel.;
Warren girder or Parallel chord truss
Parallel top and bottom chords joined by any number of W webs.;
Wattle and Daub.
A method of building walls using interlaced thin lathes or branches (wattles) that are roughly plastered over with clay (daub) typically as infill panels between timber framing. ;
Westminster Hall Roof
The oldest and largest example of hammer beam roof, built to cover the large hall of Westminster Palace in London. ;
Whaleback roof
A pitched roof that has slight convex curves to the top surfaces. Depending on the amount of curve and the ratio of width to height they can range from almost a semicircle to a gothic arch. ;
Wind brace
A structural member that stiffens a structure against the forces of the wind. It can be timber or metal, strut (in compression) or a tie (in tension).;
Wood shakes, Shingles
A roof covering made out of small wooden pieces lapped in a similar manner to roof slates.;
Z
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Z or zed purlins
Cold rolled sections in the form of a letter "Z". Used mainly in large roofs and as wall girts. Zeds have the ability to overlap at the joints giving them a great strength advantage over the Cee purlins. Also can be used as floor joists.;

Types of roofs

Barrel roof
A roof with a semi-circular cross section
Butterfly roof
A roof that could be called an inverted gable roof. Both surfaces slope inwards from the walls to a central valley.
Collar tie roof
A short span roof without a ceiling joist or other tie at the wall plates. A collar tie is used to create greater head height.
Compass roof.
A pitched roof that has slight convex curves to the top surfaces. Depending on the amount of curve and the ratio of width to height they can range from almost a semicircle to a gothic arch.
Couple close roof
A short span roof with ceiling joists as ties but no other roof ties.
Couple roof
A short span roof without a ceiling joist or other tie. The simplest of any ridged roof.
Dutch gable
A lower part of a roof end that has a hip with an upper section with a gable.
Fabric roofs
Roofs made from flexible membranes and tensioned cables. From simple shade structures to complex permanent structures.
French truss
A roof truss based on two Howe trusses and a bottom chord. A way of making a larger truss out of prefabricated elements of smaller trusses,
Gable roofs
A roof with two sloping surfaces from the ridge (usually in the center, joining at the side walls to form gable ends.
Galleria Roof
From the Italian word for gallery. The term is now loosely used to mean a roof over and between existing building to create a roofed public leisure and shopping space.
Gambrel roof.
The gambrel has two slopes to each long side, the lower slope being much steeper. To better accommodate rooms inside the roof. A gambrel has gable walls on the shorter side.
Helm Roof
A roof usually to a rectangular tower that has four gables with the ridges riseing from the gables to give the effect of a sharpened stake. Used on steeples.
Hip roof
A roof where the end surfaces also slope.
Hipped gable
A roof that has a hipped end truncating a gable.
Lattice Roof
A barrel or arched roof formed of many small sections fixed together to form the roof structure. They have been made out of RC concrete, timber, aluminium and steel.
Lean to roof
A single pitch roof. The lean to is exactly what it says, the top end of it leans against another structure.
Mansard roof
A roof that has two slopes to each side, the lower slope being much steeper. To better accommodate rooms inside the roof.
Monitor roof
A raised extension above a ridge that can provide light and ventilation to the room below.
Ogee roof
A curved roof based on the "ogee" curve.
Pavilion roof
Usually a roof set on a regular polygon with equal hips on all sides.
Polygonal roof
Usually a roof set on a regular polygon with equal hips on all sides. It is seen a a decorative roof used in gardens and parks.
Rainbow roof
A pitched roof that has slight convex cruves to the top surfaces
Shed roof
A roof that has only one slope. It is normally sat on two parallel walls that have different heights. The difference in height being the fall or pitch or the roof.
Skillion roof
An Australian term for the same single slope roof, although it is often also applied to the lean to roof also.
Whaleback roof
A pitched roof that has slight convex curves to the top surfaces. Depending on the amount of curve and the ratio of width to height they can range from almost a semicircle to a gothic arch.

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Roof Features

Apron Flashing
A flashing that seals the top edge of a roof against a wall or chimney etc.
Barge or Verge Flashing
A flashing that seals the end of a roof against the verge or gable end.
Bargeboard
A board or roll formed metal section fixed at the gable to finish and protect the roof to gable wall joint.
Box gutter
A horizontal gutter at the intersection of two parallel roof surfaces.
Boxed Eaves
An eaves that has been lined with the lining material level, rather than following the slope of the roof.
Ceiling joists
A wooden or steel beam supporting a a ceiling.
Chimney cricket
A section of roof framing to divert rainwater around a chimney or short parapet.
Clerestorey window
A window in the upper part of a wall and sometimes the lower edge of the roof to give light and ventilation to a high room.
Collar Flashing
Any type of flashing that seals an object that passes through a roof. In particular now associated with proprietary fittings to suit various circular holes in roofs. i.e. vent pipes or extractor pipes.
Curb
Curb is a name for the joint between the roof faces in gambrel and mansard roofs.
Dormer window
A vertical window placed in a sloping roof.
Eaves
The lower part of a sloping roof, the part of a roof which overhangs the walls.
Eaves brace
A brace between a wall and the eaves to increase the overhang at the eaves.
Eaves bracket
A bracket between a wall and the eaves to increase the overhang at the eaves.
Eaves lining
A sheeting or lining material to seal the underside of an overhanging eaves or verge.
Eaves Vents
A series openings in the eaves to facilitate the movement of air inside a roof space.
Eyebrow
A low dormer type projection in a roof surface with no side walls. The roof surface flows over it in a curve.
Fascia board
A horizontal board or roll formed metal fitting usually fixed vertically to the ends of the rafters
Fascia gutter
1.) A rainwater gutter that is fixed to a fascia board.
2.) A purpose made rainwater gutter that is fixed to the ends of the rafters and also performs the function of a fascia board.
Finial
1.)In architecture, a pure decoration or embellishment to the high points of a building.
2.) The top, round cap to flagpoles.
3.) Non construction related - Probably the most use it gets today is in the soft furnishing sections of stores, it is a name for the moulded caps to curtain rail ends.
Flashing
A strip of sleeve of impervious material, or a non-ferrous metal or coated steel material that is formed to stop the entry of water.
Gable
The vertical triangular end of a pitched roof. It often is a continuation of the wall it is sat on or it can be made from different materials.
Gable dormer
A vertical window placed in a sloping gable roof.
Gable Vent
A louvred vent in a gable wall.
Gablet
1). A small gable that projects from another roof surface, similar to a dormer but with no walls. It can indeed be sat at the top of a gable end but the term is rarely used in this respect any more. 2). A triangular coping to a wall or buttress.
Gutter outlet
1.) An outlet for a gutter in a wall or parapet to allow water to drain off a roof.
Gutter overflow
An extra gutter outlet or scupper at a higher level than the normal outlet. To safely direct the water outside if the main outlet gets blocked or is overloaded.
Hammer Beam
Short horizontal beams built into and braced off the walls to help create larger open spans than would otherwise be possible with the means available at the time.
Hammer Post
A vertical post from the open end of the hammer beam to the principal rafter.
Hip
The meeting of two inclined roof surfaces.
Hip flashing
The PM flashing of a hip to a roof sheeted with roll formed steel roofing.
Link dormer
A dormer that typically houses a chimney. Also used to join one part of a roof to another
Parapet
1.) The part of an exterior wall, gable or party wall that is entirely above the roof surface
2.) A low wall to guard the edge of a drop off. 3.) A defense wall.
Parapet gutter
A gutter at the intersection of a parapet wall and the bottom of a roof slope.
Pendant
A suspended feature in gothic architecture, used in stone vaults and timber roofs. Also called a pendent.
Penetration flashing
Any type of flashing that seals an object that passes through a roof. In particular now associated with proprietary fittings to suit various circular holes in roofs. i.e. vent pipes or extractor pipes.
PM flashing
"Pressed metal" material usually 0.9mm thick in the same finish as the roofing. It is cut to length and width in a guillotine and then shaped in a brake press. The lengths of the individual flashings are governed by the size of the machine available. 6M. is common.
Rainwater head
A funnel or boxlike head at the top of a down pipe or downspout for the collection of rainwater from a gutter outlet or overflow. Also know as:-rainwater header, rainwater sump, leader head, conductor head.
Ridge
The apex of a roof. The highest point. Usually where two roof surface are parallel then the ridge is a horizontal intersection of the two.
Ridge Vent
A horizontal vent to remove hot air etc. fixed to the ridge of a peaked roof.
Roof Vents
A series openings in a sealed roof to ventilate the roof space.
Roof verge
The edge of a gable roof at the gable wall. Sometimes flush with the wall and often has an overhang.
Rotary Vent
A rotary spinning extractor vent, driven by wind power only, or by electric motor. Usually fixed towards the ridge of a peaked roof.
Scupper
1.) An outlet for a gutter in a wall or parapet to allow water to drain off a roof.
2.) A grill or other device to stop debris clogging a drain or gutter outlet.
Shed dormer
A vertical window placed in a sloping shed roof.
Stepped Flashing
A flashing that seals the sloping edge of a roof against a masonry or brick wall.
Tracery
Curved openwork shapes in stone or wood of typical Gothic designs in windows openings or decorative screens.
Valley
The meeting of two inclined roof surfaces at a re-entrant angle.
Vergeboard
A board or roll formed metal section fixed at the gable to finish and protect the roof to gable wall joint.
Vermin proofing
Protecting a building against the entry of rats and mice and other vermin. Particularly at the eaves. Usually by expanded metal mesh.
Wall post
A vertical post against the wall under a hammer beam or tie beam and down to the corbel to secure the curved brace and help transmit roof loads to the corbel.

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Roof Framing

Anti ponding strip
In roofing, tiles and slating. A flat strip of metal flashing material fixed to the top o the fascia and to the rafters to stop the sarking sagging so that no water can pond inside the fascia.
Ashlar piece
Inside roof spaces, lofts and garrets, the short vertical pieces fixed between the floor and the rafters to form short walls. (Not to be confused with ashlar masonry).
Ashlaring
The short side wall frames in lofts, attics, garrets etc.
Birdsmouth
A timber joint,a notch cut out of an angled piece to let it sit on a cross member. Typically in a rafter at the wall plate or at a underpurlin.
C or cee purlins.
Cold rolled sections in the form of a letter "C". Used not only for roofs but for wall girts and they are used by shed manufactures to form columns, ties and braces. They are also used for floor joists.
Ceiling battens
Supported by and running at right angles to the ceiling-joists the battens typically timber or roll formed metal support the actual ceiling lining material.
Collar tie
In timber roofs a member which spans two opposite rafters, usually at mid span between the wall plate and the ridge to stop the rafters spreading under load.
Common rafter
A roofing timber that defines the slope of a roof. It is set at right angles to the wall plate and rises to the ridge board.
Cripple rafter, Creeper rafter
A short rafter connecting a hip rafter and a valley rafter.
Fascia purlin
Usually in steel shed roofs, a rolled formed comnination of a fascia and a purlin. Can be ordred to suit varying roof pitches.
Fascia stiffener
In an overhanging eaves, a horizontal timber behind the fascia at the hip corners to support the last jack rafters.
Fly brace
A brace from the bottom flange of a rafter to a roof purlin that restrains the rafter laterally.
Hanging beam
A beam that is on top of the members that it is supporting. Typically used in ceilings where a conventional beam would look unsightly or would reduce limited head height.
Hip rafter
An inclined board immediately under the junction of two roof surfaces, the hip. To which are fixed the jack rafters. It runs from the corner of the wall plates up to the ridge.
Jack joists
Short joists at hip ends of hip roofs, running at right angles to the main ceiling-joists
Jack rafter
A rafter that follows the same line as the common rafters, but it meets a hip instead of the ridge board. As a result it is shorter than the common rafters and has an inclined side or cheek cut where it meets the hip rafter.
Metal ceiling battens
Made out of roll formed metal. similar but smaller in profile the roof-battens. Tek screwed to the ceiling joists, more often used in conjunction with gang nail truss construction.
Metal Roof battens
Made out of roll formed metal. In a type of "top hat" section. Tek screwed to the rafters.
Pole Plate
A horizontal member, steel or timber, fixed to the face of a wall to which roof framing is fixed. Typically rafters in a lean to type of roof.
purlin
1.) A horizontal roof member, steel or timber, sitting on the principal rafter of a truss or propped off a wall to support the rafters. AKA Under purlin.
2.) A horizontal roof member sitting on the rafters or on a truss or steel member that the roofing material is directly fixed to. AKA over purlin.
Purlin bolts
Nut and bolt sets specifically designed for fixing cold rolled steel purlins. The bolt and nut heads have the washer with a serrated gripping surface formed integrally.
Purlin bridging
Lightweight roll formed metal channel sections with proprietary end fittings used to stiffen Cee and Zed purlins
Purlin cleat
1.) Steel, a MS plate or angle punched to a set pattern of holes or slots to suit a particular size of steel purlins. Either welded or bolted to the support member.
2.) Timber, a short piece of timber fixed to a support member to hold timber purlins in position.
RHS purlins
Rectangular Hollow Section. Often used as purlins on roof to decks and verandahs, where the structure is exposed to view. Usually the wall thickness used is 2.0mm or 2.5mm. Should always have welded end caps to seal the inside from corrosion.
Ridge board
A horizontal board immediately under the ridge of the roof to which the tops of the rafters are fixed.
Roof battens
Horizontal members fixed to the top of the rafters the battens vary in size and spacing depending on the roof material that they carry. In the larger sizes sometimes called purlins.
Roof framing
The total of the structural roof members which when connected form the support for the roof coverings
Scotch valley, Blind valley, California valley
A method of constructing a variation to a rectangular plan without the use of valley rafters. The method that all Multinail roof truss manufactures use. Far stronger than a traditional framed valley but requires a beam across the walls.
Sprocket-piece
1.) A piece at the foot of a rafter to incline last section of the roof towards the horizontal, to make sprocked eaves.
2.) An outrigger piece attached to the end rafters at the verge of a gable roof to create a gable overhang.
Steel purlin
A horizontal roof member to which roofing is fixed. Mostly cold rolled galvanized steel but can be any steel section thin enough to be easily screwed to.
Tile battens
In roofing they are the horizontal strips of timber nailed across the rafters to fix cement and clay tiles to.
Timber ceiling battens
Made out of timber. Fixed to the ceiling joists in the with serrated grip nails (mostly by by nail guns).
Timber purlin
A horizontal timber or lumber roof member that supports the common rafters, or horizontal roof member to which roofing is fixed, either on the rafters or on trusses etc.
Timber Roof-battens
Made out of timber. Fixed to the rafters in the smaller sizes for slates and tiles with serrated grip nails (mostly by by nail guns), and in the larger sizes by various plate connectors or straps.
Valley jack rafter
A short rafter connecting a ridge board and a valley rafter.
Valley rafter
The main support timber directly under the valley intersection of two roof surfaces. It corresponds to the hip rafter in terms of the same slope and roofing angles. It supports the valley jack rafters and any valley creepers.
Wall Plate
1.) A horizontal member, usually timber bolted or otherwise fixed to the top of a wall to which the roof framing is fixed.
2.) A horizontal member, such as a steel plate fixed to a masonry or concrete wall to carry the end of a beam or to attach a beam to other members.
3.) A horizontal member, either at the top or bottom of a wall frame. Known as top plates or bottom plates.
4.) A board fixed to a vertical surface of a wall to which shoring or props are fixed. Note! when used for the purpose of fixing rafters against a wall then it is known as a Pole Plate.
Wind brace
A structural member that stiffens a structure against the forces of the wind. It can be timber or metal, strut (in compression) or a tie (in tension).
Z or zed purlins
Cold rolled sections in the form of a letter "Z". Used mainly in large roofs and as wall girts. Zeds have the ability to overlap at the joints giving them a great strength advantage over the Cee purlins. Also can be used as floor joists.

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Roof Trusses

Aisled Barn
A type of roof truss construction that has aisles down the side to increase the span
Arcade post
A post at the side of a cruck truss to share the load and shorten the span. Usually seen in pairs in aisle barn construction.
Arched brace
A curved brace, normally out of naturally curved timbers used to stiffen a roof frame. Usually in pairs.
Base cruck
The cruck blades sit at ground level and rase to be joined to a tie or collar beam.
Belfast truss
A roof truss that has the top chord in the form of a circular or sometimes a parabolic arc. Known to be economical over large spans.
Belgian truss
Similar to a W truss or a Warren truss for longer spans with extra webs added. Also called a double Fink truss
Bowstring truss
A roof truss that has the top chord in the form of a circular or sometimes a parabolic arc. Know to be economical over large spans.
Buttress
A mass of masonry bonded to an exterior wall. Usually to stiffen it against the lateral thrust of roof structures.
Cambered Fink or Cambered Warren truss
A Fink or Warren truss with a raised center bottom chord.
Cantilever truss
A truss where one end is allowed to run over the support. Part of the truss is said to be a cantilever.
Cruck blade
A single piece of timber when paired with another similar piece becomes a full cruck frame.
Cruck construction
A category of medieval architecture of unsure origin where the main load bearing members are crucks. Large section naturally bent timbers that reach from the height of the roof to the floors. Later they extended to low side walls.
Cruck Truss
1.) One of a pair or naturally curved timbers used to form frames or trusses that were the main structural elements in medieval building in Northern Europe.
2.) A building that contains crucks or built using crucks.
Dendrochronology
In old timber framed buildings it is used to date the time that trees were felled, and so the construction date, by various methods including study of the annual growth rings and carbon dating.
Dendrology
The branch of botany involving the study of trees and shrubs.
Eltham Palace Roof
The third largest example of a hammer beam roof in the UK, built to cover the great hall of the palace built for Edward 1V in the 15th century south of London.
Fan truss
Similar to a W truss but with extra vertical ties added. Said that each sides web radiate like a fan.
Full Cruck
A cruck frame which reaches from the ridge to the floor using none jointed blades.
Gang nail truss
One of a series of trusses made with light timber sections joined together with metal nail plates.
Girder truss
A roof truss that acts a truss, but at the same time is built stronger than a standard truss of the same span to carry extra loads imposed on it. Used in nailplate truss construction. Sometimes consists of two or more standard trusses fixed together.
Half truss
Used in shed type roofs and lean to roofs, it is in effect half of a normal truss with a vertical member to complete the triangle.
Hammer Beam Truss
The ultimate development of timber roof truss design before the advent of modern materials, the hammer beam truss uses hammer beams extending a short way out from the walls to create an open and usually a highly decorative effect. The hammer beam roof is a peculiarly English creation with the finest example being in Westminster Hall.
Hampton Court Palace Roof
The second largest example of a hammer beam roof in the UK, built to cover the great hall of Henry V111's Tudor Palace at Hampton Court on the banks of the Thames near London, UK
Hip truss
One of a series of trusses made with light timber sections joined together with metal nail plates that sits in the hip position.
Howe girder
A girder or truss with horizontal chords and the diagonal members pointing down and towards the supports.
Howe truss
A roof truss with vertical web members to take tension forces and with angled braces to take compression
Iron Roof Truss
A roof truss made out of either wrought iron, cast iron or more likely a combination or the two. Capable of large spans and often highly decorated.
Jack truss
Used in nail plate truss construction, a subsidiary truss that is fixed to a truncated truss with it's top chord flying over to reach the hip. Where not fixed to a truncated truss it is fixed to a hip truss.
Jointed cruck
A cruck with joints to the main members. To extend the length of the timbers or alter the shapes.
King post truss
A roof truss mostly wooden with two principal rafters, a tie beam and a central vertical King post. The simplest of trusses. Mainly used with two angled struts.
Knee brace
A brace between a post and beam, the bottom chord of a roof truss and the support, or a stiffener in a portal frame.
Monospace truss
Used in shed type roofs and lean to roofs, it is in effect half of a normal truss with a vertical member to complete the triangle. The strut and web pattern is the same as a W truss.
Pratt girder
A girder or truss with horizontal chords and the diagonal members pointing down and towards the center.
Pratt truss
A truss with alternate vertical and angled members between the chords. They angled members pointing down and towards the center.
Principal rafter
One of the main diagonal members in in a roof truss on which the purlins sit, which in turn support the common rafters.
Queen post truss
A roof truss mostly wooden with two principal rafters and two vertical Queen posts with a restraining tie beam at the bottom and a straining beam at the top.
Raised cruck
A cruck truss that is raised to sit on usually short walls. Either masonry or timber.
Reducing truss
One of a set of nailplate roof trusses that sit on the backs of other trusses to form valleys.
Sailover truss
A truss where each end cantilevers over the support. Used to get extra height at the wall plate or to simplify boxing in the eaves.
Scissor truss
A truss with both the top chords and the bottom chords sloping upwards. To give a greater ceiling or clearance height.
Straining beam
1.) In a truss a horizontal strut above the tie beam.
2.) In a queen post truss the horizontal strut between the ends of the queen posts.
Straining sill
A horizontal member in a timber roof, typically fixed to a tie beam to resist the sidways thrust of struts.
Tie beam
1.) A horizontal member in roof framing, fixed to the foot of rafters to stop them spreading.
2.) In truss construction, timber or steel, the bottom horizontal member. The bottom chord.
Tie Rod Truss
A roof truss that uses tie rods for the members under tension, ties, and solid timber or metal for the compression members.
Truncated truss
A standard truss that has been truncated or has had it's top cut off. Usually to allow jack trusses to pass over it in hip roof design. The term girder truss truss is commonly applied as these trusses ofter act as a girder supporting the minor trusses abutting it.
Upper cruck
The upper blades are sat on a tie beam and raise up to the ridge.
W truss
A triangular truss where the web members take the form of a W.
Warren girder or Parallel chord truss
Parallel top and bottom chords joined by any number of W webs.
Wattle and Daub.
A method of building walls using interlaced thin lathes or branches (wattles) that are roughly plastered over with clay (daub) typically as infill panels between timber framing.
Westminster Hall Roof
The oldest and largest example of hammer beam roof, built to cover the large hall of Westminster Palace in London.

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Roof Coverings

Asbestos containing roofing
Any roofing material containing asbestos fibres. Typically produced in corrugated sheets, imitation slates or imitation shingles. Banned as a new construction material since around 2000 in most countries.
Cement tile roofing
A roofing tile made out of cement or concrete based products. Available in many shapes and sizes.
Copper roofing
Flat sheets of copper used as a roofing material. Very long lasting. The typical green colour of an old copper roof is a layer of oxidisation that protects the material from further deterioration.
Corrugated iron
A roll formed flat sheet roofing product that when formed with the ridges and valleys becomes stiff and strong. Called iron because it was first made out of wrought iron.
End Lap
(In Roofing) The amount by which roofing tiles, slates shingles flashings etc overlap each other to achieve waterproofing at the end, that is in the direction of the slope. Higher overlaps lower by the amount of end lap.
Imbrex and Tegula
Two Latin words that together describe a system of terra cotta roofing tiles that go back to Ancient Greek and Roman Tiles. The Tegula is a flat pan with raised sides. The Imbrex is a semi-circular tile that caps the joint between the Tegulae.
Lap
(In Roofing) The amount by which roofing tiles, slates shingles flashings etc overlap each other to achieve waterproofing. Usally referred to as either Side Lap or End lap.
Lead roofing
Flat sheets of lead used as a roofing material. Very long lasting. Used for flat roofs and pitched roofs (usually out of sight) and extremely usfull for flashings because of its malleability.
Mediterranean clay tiles
Also known as barrel or mission tiles in the US these semicircular with a taper are laid in alternate concave and convex rows.
Pantile
In the UK the name of traditional type of terra cotta or clay tile. "The Pantiles" is the name of an area in the town of Tunbridge wells, Kent, UK.
Plastic roofing
Roofing material made for patios and decks etc. to allow varying amounts of light through the sheeting. Made from synthetic materials, fiberglass, polycarbonate etc.
Roofing nail
Galvanised nails for fixing corrugated iron. About 65mm long with an integral washer they are now superseded by roofing screws.
Shingle clay tiles
Flat or slightly curved terracotta tiles fixed with similar laps and gauges to wood shingles or slates.
Side Lap
(In Roofing) The amount by which roofing tiles, slates shingles flashings etc overlap each other to achieve waterproofing at the side, that is in a horizontal direction.
Slate roofing
A roofing material consisting of overlapping layers of slate.
Slate roofs
Roofing material made from natural slate. A sedimentary rock that has the ability to be split into thin layers.
Terra cotta tiles
One of the oldest of roofing materials, these tiles are made from hard fired clay in many different shapes and patterns.
Wood shakes, Shingles
A roof covering made out of small wooden pieces lapped in a similar manner to roof slates.

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Last Updated on Monday, 14 March 2011 15:51