Flat Warm Roof Build Up

Flat roof constructions are generally classed as either cold or warm.

Flat warm roof build up.

Warm cold and inverted. There are three recognised designs of flat roof construction. It can also prevent pest from entering. 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.

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. Warm flat roof fully packed with insulation to prevent any condensation build up. In the warm flat roof construction there is insulation packed into every possible space where air can flow. In a warm roof construction the principal thermal insulation layer is located above the structural decking resulting in the structural deck and support structure being at a temperature close to that of the interior of the building.

This could mean flat roofs may not raise the same red flags they used to. But now flat roofs often are constructed with fewer layers because of improved waterproofing technology. They can be built up from profiled metal decks as the insulation selected would provide enough rigidity to span the open sections of such decks. The major difference between the warm flat roof and the cold flat roof has to do with the air flow between the roofing timbers known as joists that help to hold up the roof.

Others would treat even steeper pitches as flat roofs. A roof is mainly considered to keep out rain and snow from a building. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. Flat roofs are hard to replace.

A good roof requires maintenance like any. Flat roofs have a reputation of failing early but improvements in strength flexibility ageing and weather resistance mean that if built with care using the correct materials today s high performance felts can have a life span of up to 20 years. In a warm roof the thermal insulation is immediately below the membrane finish the structural deck any voids and the ceiling are at a temperature close to that of the building s interior condensation control is achieved by using a vapour control layer vcl on the warm side of the insulation. A great home requires a great roof.

In these days of energy preservation a roof can also contribute to preventing warmth being lost from a building.