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Roof Insulation Cost Guide

Curious to know how much roof insulation cost? This guide will cover various types of roof insulation, including spray insulation, warm roof insulation, and fibreglass roof insulation, as well as the expected costs of hiring a professional for the job.

Roof Insulation Cost
Source: All Seasons Energy

How much does roof insulation cost?

The cost associated with insulating a roof is determined by various factors such as the size of the property, the chosen materials, and the available budget.

The estimated cost of installing roof insulation in the UK typically is around £500 and can be influenced by various factors as mentioned above.

In the UK, most homes have a pitched roof, which is characterized by two sloped sides that run downwards from the central ridge of the roof. To qualify as a pitched roof, the slope angle must exceed 10 degrees or consist of more than two sides over the central ridge, as per regulations.

The majority of homes in the UK are constructed with a pitched roof design. If you’re unfamiliar with this style of roof, take a look at the image below this paragraph. As you can see, a pitched roof consists of two sloping sides and a straight ridge at the top.

Different types of roofing insulation

There are two primary methods of insulating a roof: laying insulation material above the roof joists or fixing the insulation directly beneath the sloping roof. The method you choose will affect the overall cost of the roof insulation project.

After selecting the insulation method, the next step is to choose the type of insulation material. There are various options available, each with its own price range. It’s important to consider your budget when selecting a suitable insulation material.

If you’re thinking of hiring a professional tradesperson to install your roof insulation, it’s recommended to seek out the best prices.

By hiring a professional roofer, you can save time and reduce stress. The tradesperson will measure your property, inform you about the required amount of insulation, and provide you with a quote.

Best types of Roof Insulation Materials to Use

There are several effective materials to choose from when it comes to roof insulation, such as foil-backed polystyrene roof panels, insulation boards, spray foam, glass wool, and rock wool. Each of these options offers its own benefits. The type of insulation material you select will depend on the size of your roof and your available budget.

Let’s look at this in more detail.


Fiberglass is a highly popular choice of insulation material for roofs due to its numerous advantages. In addition to being lightweight, it also provides a high level of insulation and is relatively inexpensive. However, it’s essential to note that before installing fiberglass insulation, roofing underlay must be put in place. To complete the task correctly, a vapour barrier must be installed to prevent the insulation from absorbing moisture from the room.

The typical cost of fibreglass roof insulation per square metre is approximately £10. If you’re hiring a professional tradesperson to supply and install fiberglass roof insulation, you should expect to pay roughly £20 per square metre.

Rock Wool

Rock wool is a suitable option for those who prioritize sound insulation. It provides both roof insulation and sound reduction. Compared to glass wool, the cost of rock wool insulation is higher as it is made from volcanic rock that is heated to a high temperature to create a dense, spongy material.

On average, rock wool roof insulation costs approximately £20 per square metre. If you plan to hire a professional to install it for you, the cost can go up to around £30 per square metre, which includes both the supply and installation of the material.

Insulation boards

They are considered to be one of the most effective ways of insulating a roof. These boards have a diameter of 1.5 inches and offer a high level of insulation. They are available in various sizes, making it easy to insulate roofs of any size. In addition, insulation boards have acoustic properties that help reduce noise in addition to retaining heat within your home.

The cost of using insulation boards to insulate a roof averages around £11 per square metre. If you plan to hire a professional to install the insulation boards for you, the cost will be higher, ranging from £20 to £25 per square metre, including the cost of the boards.

Tabled below is a rough estimate of different scenarios based on the types of insulation and type of roof. You can use this as a guide to better understand the roof insulation cost.

Fibreglass InsulationPitched Roof20 Square Metres1 Day or Less
Mineral Wool RollsPitched Room20 Square Metres1-2 Days
Spray InsulationPitched Roof20 Square Metres1 Day or Less
Warm Deck Insulation BoardsFlat Roof20 Square Meters1-2 Days

Process of Installing a Roof Insulation

Installing roof insulation involves a simple process of preventing heat from escaping out of a house. While it can be easy to install, it is recommended to hire a professional tradesperson for the best results. 

When hiring a qualified contractor, they will determine the type and size of the roof that needs to be insulated, discuss the options available, and advise on the materials and methods suitable for your specific circumstances. 

The roofer will also check for any previously failed insulation and assess the ease of access to the roof before installing the insulation.

A professional insulation specialist will ensure that your attic space is free of moisture and dampness, which can affect the effectiveness of the new insulation. In some cases, a removal team may need to visit your property a few days before the installation to prepare the space. The insulation crew will install the new insulation once the space is clean and free of any obstacles. The installation process typically takes a few hours and can be completed within one day, depending on the complexity of your roof and the project size.

Warm vs Cold Roof Insulation

Warm Roof Insulation is the most commonly used method of roof insulation. It involves installing insulation materials between the weatherproof layer of the roof and its structure or rafters. This method ensures that the heat inside the property is retained within the space.

On the other hand, the Cold Roof Insulation method is not actually cold, as the name suggests. This method involves installing insulation above the roof joists, which only retains heat within the rooms located below. Therefore, any ceiling, attic, or room space above the insulation will not maintain as much heat.

Why is roof insulation important?

According to Energy Saving Trust, in an uninsulated home, a significant amount of heat is lost through the roof – around a quarter of it. Insulating your loft, attic, or flat roof can be an efficient way to reduce heat loss and lower your heating bills.

Installed correctly, loft insulation should pay for itself many times over in its 40-year lifetime.

Need help with roof insulation?

If you are confident enough to tackle the task on your own, calculating the cost of roof insulation should not be too difficult. First, determine your budget, measure the area to be insulated, and purchase the appropriate insulation materials within your budget.

Ensure that you are aware of all the hazards involved in handling certain types of insulation, as they may cause skin irritation and possible breathing difficulties.

If you would like to receive a FREE no-obligation quote from fully trained professional insulation specialists to install roof insulation in your home, we highly recommend that you get in touch with us.

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