As you consider repairing or installing a flat roof on your property, two effective insulation options to keep in mind are a cold flat roof or a warm flat roof design. In the past, most people used insulation on flat roofs to keep their homes cold. However, recent changes in how we live – such as spending more time inside and having internal washing and cooking areas – have led to an increased need for water vapour control. Warm flat roofs are typically seen as the better design because they eliminate many of the issues that traditional designs have.
In this post, D&D Roofing are going to discuss the different types of insulation for flat roofs, their benefits and their drawbacks, so that you can make an informed decision about which one is right for your needs.
The insulation layer is placed between, or under the timber rafters – level with the ceiling joist in the alternative roofing insulation design. As a result, the roof and trunks are kept cool by an air-permeable barrier that separates the insulation from the roof structure. In cold roofing designs, because of the necessity for ventilation in roofs, it is generally not advised as a new build flat roof design.
In a warm roof design, the insulation layer is situated either above the timber rafters or between the structural supports. This way, the temperature in the loft area is similar to that of the rest of the building, resulting in less heat loss.
Warm roofs are constructed to keep the entire building warm in order to prevent cold bridging, which is a term for when heat or energy escapes from one area of the structure and enters another. Warm roofs come in two varieties. A sandwich system is one in which there is a build-up of VCL, insulation & membrane over the structural deck. This can be done with full adhesion or mechanical fixing. An inverted system is where the insulation boards are laid over the structural deck and waterproof covering instead. The insulation is secured by a layer of ballast or paving slabs to prevent wind uplift from occurring.