Flat Lead Roof Build Up

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

Flat lead roof build up.

When a hot roof surface is suddenly cooled by rain the pressure in the area between the vapour barrier and roof covering can fall below atmospheric. Some carry warranties of up to 20 years approaching those for sloped roofing. More about lead as a building material. This can lead to underside corrosion.

Correctly laid lead roof greyfriars roofing note the height of steps between bays the rolled joints and adequate overlaps problems. That will help you remember certain factors and details to build the best possible flat roof. The fixing of lead sheet is carried out in many different ways all of which are dependent on the particular application. In a cold roof build up the vcl normally ends up on the underside of the joists or rafters and is punctured many times when covered over by the internal finishes.

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. Should the ceiling below also have downlighters the vcl could be seriously damaged and therefore virtually useless. The vcl in a warm roof. Others would treat even steeper pitches as flat roofs.

Given that the specially selected insulation layer is loose laid it will require ballasting to guard against wind uplift or floating in wet conditions. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. Coupled with some edging features to stop the vegetation leaking away this makes a green roof build up quite. They require a root barrier to stop the plants interacting with the waterproofing beneath and a flat roof in particular requires a drainage layer to retain water.

Having a manual for warm flat roof construction with details and a summary of rules to follow helps. Warm flat roof fully packed with insulation to prevent any condensation build up. Where insulation above the roof void allows the air underneath to stay warm avoiding condensation but also allows for an air flow should one be deemed to be required through the joists. If you build and flash one right and keep it clean a good flat roof won t leak says toh general contractor tom silva who had seven different flat roofs.

Fortunately modern materials for covering flat roofs have improved considerably over the past two decades. 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.