What Is The Difference Between Warm Deck & Cold Deck Roof?

The terms "warm deck roof" and "cold deck roof" simply refer to the position of the insulation in an overall build-up. A warm deck roof, for example, places insulation above rafter level, indicating that the rafter space beneath is "warm". Whereas, insulation in a cold deck roof, is installed beneath the rafters. The term "cold deck" doesn't mean that the roof itself is cold, but rather that anything above the insulation is subject to colder temperatures. This happens because there's no barrier over the top of the rafters to prevent air from seeping in and circulating through them.Let's break down each method below. Cold Deck: Installing insulation in a cold deck roof at ceiling level creates a colder temperature void, especially during winter, which can contribute to the formation of condensation. This can lead to rotting timber, damp ceilings, and damaged structural integrity. As a result, it's critical to make sure the void is well-ventilated. Warm Deck: In a warm deck roof, the insulation is installed below membrane on top of the roof deck--usually with a vapour control layer placed underneath the insulation. With this type of construction, there's much less risk of condensation because there is no cold surface upon which the condensation can form and the void remains at a similar temperature to the roof.

What Is The Recommended Depth For Loft Insulation?

Current building regulations recommend a minimum insulation depth of 270mm (blanket insulation such as mineral or glass wool) in the loft. Multiple layers can be added to the build-up to achieve this.

Do You Need To Vent A Flat Roof?

We highly suggest that you ventilate a flat roof; regulations advise that you leave a 50mm gap between insulation and the underside of the roof covering. This applies to both warm and cold roof spaces.

What Are The Four Main Materials Used in Roof Insulation?

Fibreglass insulationInsulation boards/insulation panelsGlass mineral wool insulationSpray foam insulation (PUR)

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