An Ultimate Guide to Cold Roof Insulation

Uninsulated roof structures are responsible for over 26% of heat loss experienced in a home. Nearly a quarter of all properties in the UK have uninsulated roofs, leading to strained heating systems, abnormally high carbon emissions, and damp drafty homes. 

Luckily, cold roof insulation is an affordable and thermally effective way to boost your home’s heat retention, leading to big savings, less carbon emissions, and a comfortable indoor climate. This ultimate guide by GreenMatch UK will provide all the information you need about cold roof insulation, including the process, best materials, costs, regulations and much more.

Ready to insulate your roof? Let GreenMatch UK free you from the burden of endless research and vetting. By spending just 30 seconds filling out our online form, you can receive up to 3 free home-tailored quotes from our nationwide network of professional installers. No costs or obligations apply. Click the button below to begin! 

You may be wondering; what is a cold roof? Cold roof insulation is when insulation material is placed between and below the roof rafters, leaving the pitched or flat roof structure uninsulated. Insulating a cold roof will still provide adequate loft insulation but with a lower thermal efficiency when compared to warm roof insulation. Cold roof insulation is best suited for loft spaces that will be used as storage rather than living areas.

Nevertheless, cold roof insulation comes with plenty of benefits. Primarily, it’s more cost-effective than warm roof insulation and requires less labour as all the work can take place from inside the loft, leaving your roof structure unchanged from the outside.

Building regulations roof insulation wise, outline a series of requirements to follow, as set out in Part L of the UK Building Regulations documents. These regulations look at desired u-value, cold roof insulation thickness, and what property changes can take place without a permit.

Cold flat roof insulation involves placing insulation material under the structural deck of the roof, as well as adding a waterproof layer to reduce the risk of moisture ingress. 

Unlike with warm flat roof insulation between joists, the roof deck remains uninsulated and is exposed to external temperatures, an air gap for ventilation of around 50mm is left between the structural deck and the insulation material to further help avoid moisture buildup.

Cold flat roof insulation between joists is significantly cheaper than a warm flat roof job but is less energy efficient as well. Nevertheless, it’s a drastic improvement for flat roof properties that have no roof insulation in place at all.

Cold pitched roof insulation is when insulation material is fitted in between and under the roof rafters, leaving the roof structure itself uninsulated. This method is a cost-effective way to insulate your roof without the costs and work labour of removing or replacing your roof tiles.  

Another key advantage is that cold-pitched roof insulation will still provide some degree of thermal protection for your loft space. Whilst not as efficient as warm-pitched roof insulation, its cost-to-effectiveness ratio makes it a very worthy investment if you are on a lower budget.

In the pitched roof approach, it's also important to remember to add dormer insulation if your roof has a dormer section. That way, you can achieve the best thermal enveloping.

There is no single best roof insulation material for insulating a cold roof, but there are a series of popular insulation materials on the market suited to all types of budgets, performances and conditions. Here’s a rundown of some of the best on the market:

There may be no single best insulation for cold flat roof jobs, but there's certainly no shortage of materials on the market, even beyond the list we’ve provided. The best choice can be made with the help of a professional installer through a house assessment to help you choose the most effective course of action.

However, finding a professional installer at the right price can be a daunting task, requiring countless hours of research and vetting. Luckily, GreenMatch UK can free you of this burden.

By spending just 30 seconds filling out our online form, you can receive up to 3 free home-tailored quotes straight from our network of trusted installers. Free of charges and obligations. Click below to begin!

On average, cold roof insulation for a standard detached UK house costs around £1,100 for a full insulation job. A roof insulation cost can fluctuate depending on your insulation material, outstanding repairs that need addressing, and job complexity amongst other things. 

Here’s a breakdown of some insulation material insulation costs per m2, to give you an idea of the price ranges for the most popular roof insulation materials on the market today:

Alongside the price of your chosen insulation material, your roof and loft size, installation complexity, and sometimes even location can play a significant role in your final investment.

There are several building regulations for roof insulation to ensure that your insulation job is as thermally efficient as it can be, and does not pose a risk to you or your neighbours. 

Here’s a rundown of the key regulations you can expect:

For a full picture of all the building regulations in place, make sure to consult Part L of the UK Building Regulations document, available online and on the official UK government website.

The main difference between a warm roof and a cold roof insulation job is that warm roof insulation also thermally envelops the entire roof structure, including the rafters and beams. This makes for a much more thermally efficient roof insulation in comparison to a cold roof. 

However, homes that intend to use their loft area as a storage space can save money on roof insulation by opting for a cold roof insulation job. While less thermally efficient, cold roof insulation provides adequate thermal enveloping to allow the loft area to be used, whilst still providing a decent degree of temperature regulation.

On the other hand, if you plan to use your loft area as a living space, it’s highly recommended to go ahead with warm roof insulation between joists or rafters. While your initial investment may be higher, the exceptional thermal efficiency will convert your loft into a liveable space, and lead to massive reductions in your energy bills.

All in all, cold roof insulation is a great way to improve your home's thermal performance on a budget, but it’s important to decide how you would like to use your loft space. Here’s a breakdown of the key pros and cons associated with cold roof insulation:

Ready to get cold roof insulation? Great! The next step requires finding the right installer at the right price. The process of landing the best bargain can be tricky though, with most customers stuck in endless hours of researching and vetting. Luckily, GreenMatch UK can free you of this burden.

By spending just 30 seconds filling out our online form, you can receive up to 3 free home-tailored quotes from our network of trusted professional installers. The best part? Our services are free of charges and obligations. Simply click the button below to begin!