Roof Insulation: Your Complete Guide To Warm, Cold And Hybrid Roof Systems

Have you heard that poorly fitted insulation could cause condensation issues? Or that some insulation materials can absorb water and lose their insulating properties? Those are very real risks, but what can you do to avoid wet, draughty ceilings and uncomfortable indoors?

The solution is simple! If you understand your roof type and its requirements, you can select the correct insulation solution and install it to the correct standards.

Of course, there are several ways you can insulate your roof: warm, cold, or hybrid solutions. The choice is yours, but it’s essential to understand what you’re choosing. Whether you go for a quick DIY fix or a professional installation, you’ll want to choose the correct product and install it using the correct techniques. Otherwise, it could end up being money down the drain!

It’s not nearly as difficult as it sounds. We can help you! By the end of this article, all your questions on roof insulation will be answered; so read on to learn more… 

What is roof insulation?

In simple words, roof insulation is like a long-lasting blanket for your home; creating a barrier between the inside and outside environments. The insulation material — which creates the barrier is made of materials that don’t easily conduct heat, or transfer moisture.

Roof insulation with SuperFOIL

Which means, once installed properly, these insulating materials prevent warmth from leaving your home in winter and excess heat, humidity, and moisture from entering your home in summer.

That’s right, quality insulation does have that dual benefit: it keeps your home warmer in winter, and cooler in summer.

What Benefits Do You Get From Roof Insulation?

1. Temperature Control and Comfort: A well-insulated roof regulates indoor temperatures year-round. During the winter, it prevents up to 25% of heat loss that normally occurs through uninsulated roofs, keeping homes warmer and reducing the need for excessive heating. Similarly, during summer, it helps maintain a cooler indoor environment by blocking the Sun’s radiant heat from entering through the roof.

2. Energy Saving: Minimising heat loss or gain means your boilers and air conditioners don’t need to work as hard to keep your rooms warm or cool, which saves you money on your energy bills. Plus, since insulation is a long-term investment, you’ll be saving for years to come.

3. Moisture and Vapour Protection: Many modern day roof insulation products, like multifoil can serve as a barrier against moisture and condensation, preventing dampness and mould growth. Which means, proper insulation with adequate ventilation not only ensures a dry and healthy indoors, but also extends your roof’s lifespan by minimising leaks and cracks. 

4. Sustainability: Improving your property’s insulation means improving its energy performance. Improved energy performance equates to lower carbon emissions and a smaller ecological footprint coming from heating and cooling your home. This can be further enhanced when you choose an insulation product with high sustainability credentials. 

5. Property Value: Increasingly stringent energy efficiency standards mean that homes with improved energy performance ratings (D or above) are becoming more desirable.

Insulating your roof can therefore increase the overall value of your property as the demand for energy-efficient buildings continues to rise.

Building Regulations Requirement for Roof Insulation

In the UK, most homes lose heat much faster than those in other European countries due to having some of the oldest housing stocks. To tackle this issue, the UK Building Regulations set minimum standards for insulation to ensure buildings are energy efficient. These regulations require new buildings, extensions, and significant renovations to meet specific thermal performance criteria, known as U-values. The lower the U-value, the better the insulation. If you want to learn more about current building regulations requirements and u-values for roofs, you can visit our building regulations page.

Complying with these standards is essential not only for legal reasons but also to achieve long-term energy savings and maintaining property value. By adhering to these regulations, you can be sure that your property is well-insulated, comfortable, and cost-effective too. 

Warm Roof, Cold Roof and Hybrid Roof Insulation

If you are insulating your property to get the most benefits, you’ll likely find it helpful to know your options better. So, let’s begin that discussion by breaking down the different types of roof insulation systems.

The three main types of roof insulation system are warm roof, cold roof and hybrid roof and the major difference is based on how the insulation material is placed within the roof structure. 

What is a Warm Roof?

A warm roof is the most popular insulation type because it’s highly thermally efficient. In a warm roof structure, the entire roofing system is insulated by fitting the insulation over or under the rafters in a pitched roof or over the joists in a flat roof.

Roof Insulation Install using SuperFOIL Breathable

Benefits of warm roof insulation

1. Warm roof insulation keeps the entire roof deck and the supporting beams under the insulation envelope. Using a continuous insulation layer, such as multifoil insulation, prevents heat loss through thermal bridging or in other words heat loss that usually occurs through breaks in insulation across wooden rafters and joints.

2. The even layer of insulation ensures consistent internal temperature and helps prevent condensation issues within the roof structure, as the roof deck remains warm, reducing the risk of moisture buildup.

3.  Warm roof systems usually don’t require ventilation, as it is designed to limit moisture and condensation issues.

4. The possibility of roof structural damage over time will be limited, as a warm roof avoids temperature fluctuations and moisture buildup.5. When insulating on the external side of the rafters/joists, the property can typically remain fully habitable while the insulation works are being carried out.

Drawbacks of warm roof insulation

1. Warm roof insulation can be more complex and costly, often requiring professional installation to ensure proper sealing and vapour proofing.

2. In some retrofit scenarios, the existing roof structure might not support the added weight of the insulation, calling for structural reinforcements that add to the overall cost and effort of the project.

3. When insulating on the external side of the rafters/joists, the additional layer of insulation placed above the roof deck, will increase the roof’s structural height. This added height may pose an issue in areas with strict building height regulations or where maintaining the existing roof profile is important for aesthetic reasons. 

What is Cold Roof Insulation?

Cold roof insulation is another popular choice among residential properties due to its ability to maintain a thinner roof profile. In this set up, the insulation is placed at ceiling level, below the joists. Through this type of insulation, you insulate the living spaces below, while leaving the roof space exposed to cold air. 

Benefits of cold roof insulation:

1. Cold roof insulation is generally easier and less expensive to install.

2. Cold roof doesn’t require much structural modifications.  

3. Cold roof insulation won’t add additional height to your roof.

Drawbacks of cold roof insulation:

1. The roof deck is exposed to outside temperatures, leading to temperature difference, thermal bridging and potential condensation problems, especially in winter.

2. The uninsulated roof space can increase energy loss, as cold air circulates.

3. As per the building regulations requirement (BS5250), cold roofs require effective ventilation if the span of roof is anything more than five metres.


What is Hybrid Roof Insulation?

Now that you are familiar with warm roof and cold roof insulation, it is easier to understand hybrid roof insulation. Hybrid roof insulation is a dual insulation approach combining elements of both warm and cold roof insulation. In this setup, insulation is placed both over and under the rafters in pitched roofs and over and under the joists in flat roofs. 

SuperFOIL product applied to a flat roof - over joist
SuperFOIL product applied to a flat roof - under joist

Benefits of hybrid roof insulation:

1. For buildings requiring high energy efficiency and optimal insulation, hybrid roof insulation presents a balanced solution by completely limiting the occurrence of thermal bridging, heat loss, moisture damage, and condensation.

2. Hybrid roof insulation offers more flexibility in design and application, allowing for the use of different amounts and types of insulation materials to meet specific building regulations or accommodate complex building structures.

3. The enhanced thermal performance helps extend the lifespan of the roof structure.

Drawbacks of hybrid roof insulation:

1. The major drawback of hybrid roof insulation is the time and cost required to complete the works.

2. It can only be carried out by a skilled installer, as it requires installation of a new finished roof covering. Tiles on a pitched roof and waterproofing layer on a flat roof. More careful planning and execution is needed to ensure that both layers of insulation (above and below) work effectively together without creating moisture traps or condensation issues. 

Roof Insulation Products From SuperFOIL

One of the biggest benefits of SuperFOIL is that we have an extensive range of products to address practically any of your insulation needs. The 3-in-1 design of our Multifoil Insulation products combines insulation, radiant barrier, and a vapour barrier (VCL) in a single product. While the highly reflective foil acts as a radiant barrier to prevent unnecessary heat gain or loss by reflecting heat, the VCL properties prevent the risks of moisture penetration, condensation, and mould growth. Finally, the internal layers act as a great insulator, preventing heat from passing in/out of the build-up.

Alternately, SuperFOIL’s Breathable Insulation range (SF19BB and SF40BB) is ideal for external applications, offering a reflective W1 watertight breathable membrane. Therefore, the multilayered insulation product offers additional protection to your build-up by acting as a secondary rain barrier while still allowing moisture to escape. The remaining layers are perforated to keep the whole product breathable, whilst still providing high thermal performance.

When installed in continuous layers, multifoil insulation protects your property from heat loss or gain, temperature fluctuation, and condensation, ensuring year-round protection and substantial savings on your energy bill. The multi-functional and easy to install design also simplifies your insulation job, saving you space, time, and money all at once.

To find out more about how easy SuperFOIL is to install, visit our applications page here. 

What type of insulation is best for YOUR roof?

We’ve presented all three roof insulation methods with their benefits, drawbacks and applications. Now, you have everything you need to make an informed choice on which option is the best for you. 

Proper roof insulation is a smart investment that pays off through lower energy bills, increased property value, and a reduced environmental impact; all of which means you absolutely want to make sure you get it right. So if you are confused about where and how to begin with your roof insulation, we recommend getting in touch with us.

Our expert support team can take care of everything for you; and we really do mean everything. A discovery session to understand your concerns, a condensation analysis, product specification advice, u-value calculation, install recommendation, quote requests from your nearest insulation distributor, and, if you want someone to install the product for you, we can even connect you to our network of fully trained installers. Phew! All taken care of from step one, so you don’t need to worry about anything. And all of our services are completely free of charge, without ANY OBLIGATION TO PURCHASE.

Reach out for a free discovery session: [email protected] / 01636639900. Request for a free sample of our product here.


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