Warm Roof vs Cold Roof: What's The Difference?
Are you planning a roof insulation project? No matter if it's a conversion, extension, newbuild or just routine maintenance, you'll first need to consider if you'll be using cold roof ventilation or warm roof insulation. And that's where we can help. With an extensive range to choose from, we'll make sure you get the products you need.
First, however, let us help you make the right choice when you order online from us. Knowing if you're insulating a cold or warm roof construction can make a significant difference. There are advantages and disadvantages to each. So, read on to find out more. That way, you can get the right materials for the job delivered direct.
What is a warm roof construction?
In a warm roof, the insulation can be installed above and between the roof rafters. The aim of warm roof insulation is to provide a layer that stops heat escaping and cold air from getting in. As the diagram below shows, the insulation – such as Thermafleece – is fitted in between your roof covering membrane and internal lining board.
How does a warm roof system work?
It is common to hear a warm roof system described as a "breathable" style of roof construction. This works in two main ways. First, the thermal properties allow a property to conserve its heat without needing ventilation. Second, it lets moisture escape. This can be a very effective way to reduce the risk of damp or decay.
Is warm roof insulation right for me?
A warm pitched or flat roof construction is a popular choice. It has the advantage of being both cost effective and quick to install. As long as the roof deck is in good quality, it can be installed in an existing roof – as well as new builds. It is also well-suited to the temperate UK climate.
Actis Hybris insulation, for example, offers year-round insulation. The honeycomb design offers high thermal performance, which is certified by the Local Authority Building Control. Meanwhile, Rockwool RWA45 bonded slabs come in different thickness and density options to best suit your requirements. In each case, however, a warm roof system delivers much-needed durability.
One main issue to think about with a warm roof construction is the ceiling height. If it is limited, the insulation will reduce the height of a room. It could also restrict access to doors or windows. This is why warm flat roof constructions are not as common as a pitched alternative. The higher profile lends itself more naturally to creating that extra layer of insulation in the roof system.
What is a cold roof construction?
In a cold roof, the insulation can be found between the rafters or floor joists. Unlike in a warm roof, there is no layer between the covering membrane and the actual structure of the roof. It doesn't mean a cold roof construction is cold as such. It just means that, in relative terms, it'll often be slightly less efficient than a warm roof.
What are the features of a cold roof?
In some situations, a cold pitched or flat roof construction is either the only or most convenient solution. For structures such as conservatories, for example, the solid or glazed roof won't have a design that allows moisture to escape. There's also usually a gap between the insulating layer and roof deck. In this gap, air is able to circulate – and cold air can sometimes enter.
On a colder day, therefore, the air is conducted by the uninsulated rafters into the rooms below. This process – known as thermal bridging – can lower the overall temperature of a home or other structure. But there are ways to avoid this 'thermal bridge'. A breather membrane, for example, can be installed. The compromise is that the ceiling or headroom will be reduced.
Do I need cold roof ventilation?
For this type of construction, it's likely that you'll need to include a cold roof ventilation system. It's especially important in a cold flat roof construction to stop moist air and condensation from accumulating. Over time, this can increase the risk of roof structure damage or even failure.
In the UK, government regulations state that all new cold roof constructions must be ventilated.
Is a cold roof system right for me?
For some projects, a cold roof can provide the most effective and convenient insulation solution. It's often much easier to install at the build phase and we can supply options such as Isosaver's Spacesaver to make that possible.
You might also consider a cold roof for structures where it's necessary to maintain headroom. It isn't advisable, however, to use a cold roof with high humidity spaces e.g., a sauna. With larger volumes of warm air, using a cold roof creates a much greater risk of condensation.
Warm Roof vs Cold Roof: The key points to consider
As our guide explores, there are several key factors to think about when deciding between a warm or cold roof construction.
The benefits of a warm roof system are that it's quick to install and can often prove the most cost-effective solution. It also allows moisture to escape, which reduces the risk of damp and decay. At the same time, it is highly effective at keeping the heat within a property.
On the other hand, however, a cold roof system is a low impact solution and can be easier to install in some flat roof designs. With balconies and extensions in particular, a core benefit of cold roof constructions is that it won't restrict the headroom you have either.
Don't forget, however, that roof ventilation is essential with a cold roof. As such, it could add extra costs to your project if not planned properly.
At Burton Roofing, we supply an extensive range of roofing insulation and ventilation options that provide the right materials for any project. From insulation boards to Thermafleece rolls, products in stock that are ordered before 2pm can be delivered direct the next working day.
Get what you need at a price that's right from Burton Roofing – a brand you can trust.