Lead Flat Roof Construction

The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls.

Lead flat roof construction.

When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. Others would treat even steeper pitches as flat roofs. When a hot roof surface is suddenly cooled by rain the pressure in. Lead in use lead flat roof greyfriars roofing laid in stepped sections or bays to allow for expansion all joined by raised rolls.

The definition of a flat roof according to bs 6229 is having a pitch less than 10 o to the horizontal however some in the industry would consider up to 15 o as their definition of a flat roof. Correctly laid lead roof greyfriars roofing note the height of steps between bays the rolled joints and adequate overlaps problems. Note no nails in the edge. A new lead bay fitted in a simple one piece bay like this one the lead is nailed into the upstand underneath the guttering the drip is then beaten nice and tight over the edge of the roof and trimmed to about 50mm.

Traditional lead roof coverings are normally weathertight but not watertight. Lead flashings john gilbert used here to make a long lasting complicated junction lead worked to cover a skylight john gilbert a good long lasting repair typical problems. For additional stability you can also use steel joists that are built into one or both of the walls. So any timber joists that are used need to be strong enough to support this weight.

Sizes of joists needed for flat roof construction. Cracking from being laid in such a way that. Investigative work carried out on warm roofs covered in lead has shown that in rare instances moisture can also be introduced by the development of sub atmospheric pressure in the roof space. Lead is commonly used for flat roofs because of it s long life and ability to be formed to fit many positions lead must be laid and formed correctly to achieve this long life however.

British and european standard bsen 12588. Rolled lead sheet is the only lead sheet produced to a. When the lead rests directly onto sawn timber on a steeply pitched roof and non resinous timber has been used underlay may not be necessary. On a low pitch roof where the lead isn t free to move it is more likely to buckle on expansion or stretch as it contracts.

As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. Old asbestos roofs are often replaced with flat roofs. Flat roof roll and drip intersections 42 pitched roof joints and. Used to join lead together into smaller pieces reduce expansion and contraction issues create up stands and troughs provide.

Associated lead mills ltd jamestown metals ltd. More about lead as a building material. The temperature of lead on a roof varies constantly.