Should you create a warm roof or a cold roof?

Here at Enviroply, we are the North West’s leading roofing experts. We can provide a variety of effective roofing solutions for any commercial or industrial property. Our single ply roofing membranes are one of the most popular roofing options, and these are always paired with high quality insulation features. But the issue of insulation, is often a contentious one. This is where the warm roof vs cold roof debate takes centre stage. So should you create a warm roof or a cold roof? And what exactly is the difference between these two options? Well we have produced this guide to warm roofs and cold roofs: what’s the difference and when should you choose them?


What is a warm roof or a cold roof?

You create a warm roof, or a cold roof, simply by applying the layers of the roof in a different order. Namely the insulation layers. In a cold roof, the insulation is applied between the rafters, but in a warm roof, the insulation is applied on top of the existing roof surface. So what kind of difference does this make? Should you create a warm roof or a cold roof? Well, let’s take a look at the details.


What is a cold roof?

So what exactly is a cold roof? Well, a cold roof is created by laying insulation between the rafters. Which makes sense, as this space is otherwise empty, and so it’s a simple, low-impact way to insulate a roof.

A cold roof design usually leaves a 50mm gap between the top of the insulation, and the roof deck above. This allows air to circulate. However, this also allows cold air to enter. As a result, this type of roof is known as a cold roof. The roof structure, above the ceiling, is not insulated at all. This means that on a cold day, the cold air conducts through the rafters, into the air flow space, and subsequently into the room below. This can dramatically influence the temperature of the room, and your property as a whole.


So, what is a warm roof?

In contrast, a warm roof is one designed to keep the entire roof structure warm. This is because the insulation is laid over the top of the roof deck, on top of a vapour control layer, and underneath the roof covering. This process offers a greater level of thermal insulation, for your whole property. It’s also simple to install, as long as your existing roof deck is in good condition.


Should you create a warm roof or a cold roof?

To make an informed decision, you don’t just need to know the differences between the two options, you also need to know the different advantages and disadvantages.

So for a cold roof, the advantages are:

  • easy installation option when you first build a flat roof because the insulation can be applied during construction
  • low impact insulation doesn’t affect the profile of the building
  • makes use of otherwise wasted space

But the disadvantages are:

  • thermal efficiency is fairly poor because of the exposed rafters
  • repairs involve ripping off the roof structure, which can make it more expensive

For a warm roof, the advantages are:

  • ease of installation over the top of your existing roof deck (as long as it’s in good condition)
  • better thermal performance

But the disadvantage is:

  • an increased building height

For professional advice and support choosing between a warm roof and a cold roof, or a quote, get in touch with the professionals today, here at Enviroply Roofing.