Cold Roofs vs. Warm Roofs - Britmet Lightweight Roofing

In building & construction terms, a roof pitch is ‘the measure of how steep a roof is in a numerical form’. Using this measurement, you can work out the rafter length of the roof against the flat length. At Britmet Lightweight Roofing, we manufacture tiles that can be effectively used as cladding (90° pitch) as well as rooftiles, including our Pantile 2000 product that can reach a pitch as low as 5°.

A warm pitched roof and a cold pitched roof have many differences, both can achieve insulation albeit one better than the other, but they also differ in the mode of installation. A building with a warm roof will make the full structure warm to avoid cold bridging. An insulation layer is added above the rafters and below the rafters are a waterproof, breathable membrane; this allows moisture to escape avoiding any damp spots or mould build up. Within the UK market, this is perceived as the most suited form of roofing due to the climate as it provides a cost and thermally effective solution. Britmet’s roof tile range are based on classic UK tile profiles so you will find a tile to match your existing roof.

Cold Roofs:

Heat loss is the biggest item to consider regarding cold roofs as you must compensate for it with a heating system. The cost of regulating the temperature in a home with a cold roof is a lot more costly than a warm roof, therefore increasing household heating bills and perhaps even added costs of electric heaters etc.

In addition, it can also be expensive to construct a cold roof over an existing roof. Cold roof insulation is more commonly used for flat roofing because it’s a relatively easy process. However, cold roof insulation on an existing flat roof system is not simple. This is because you (or your installer) will have to rip the roofing material apart to lay the insulation on the surface, above the ceiling, and then install a new roof which adds to the cost and timescale of the project. A cold roof design requires roof void ventilation which can be hard to achieve with a low pitch, whereas Britmet Lightweight Roofing tiles have low pitch capabilities as low as 5°.

Warm Roofs:

Insulation on the whole roof structure, keeps everything in the roof space at the same temperature. As a result, there is reduced thermal bridging, preventing heat loss from the rest of the house. Houses with warm roofs are considerably cheaper to keep warm than those with cold roofs. Furthermore, the ceiling space is as warm as the room below, so the dew point (the temperature where air is saturated with water vapor) is outside the house; this means that there is no need for roof space ventilation. Since condensation cannot occur within a house, there is no need to worry about the build-up of moisture which would cause damp and mould.

Unlike installing a cold roof, demolition of the roof surface is not needed as it’s quick and easy to install a warm roof whether on a new or existing roof. Britmet’s Installation guide shows you the quick and easy process of building our roofs.


Overall, warm roofs are much more straightforward to install and provides an outstanding thermal performance, while cost of regulating the temperature in a home with a cold roof is tenfold than that of a warm roof.

If you have any concerns with your roof or have any unanswered questions, give our office a call on 01295 250998

Date Posted: 7th February 2020

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