Spray Foam Insulation: A Comprehensive Guide

Spray foam insulation has become increasingly popular in recent years.

The cost of heating a house has risen sharply in recent years. As a result, many homeowners are keen to improve the energy efficiency of their homes. One way to do this is to increase the insulation in your property.

Spray foam’s insulating properties are so effective that it was included in the Government’s Green Home Grants scheme. However, over the last 12 months, we’ve seen several reports of mortgage companies refusing lending on properties with the insulation. So, what’s the truth? Is it safe to use in your home and will it make it difficult to sell?

In this guide

What is spray foam insulation?
Why is spray insulation popular?
How much does spray foam insulation cost?
Is spray foam insulation good for your property?
Is spray foam insulation safe?
Spray foam insulation problems
What’s wrong with spray foam loft insulation?
Impact of spray foam insulation for homeowners
Should I buy a house with spray foam insulation?
Is spray foam making homes unsellable?
What can you do if you already have the insulation in your house?
What’s the answer for the insulation industry?

What is spray foam insulation?

Insulating foam spray is made of two key ingredients: polyurethane and isocyanate. When the two combine, a chemical reaction causes them to expand and harden.

There are two types of foam insulation – open-cell spray foam and closed-cell spray foam.

Closed-cell foam is hard and dense when set. This makes it an effective insulating material because it stops warm air from escaping from your home.

Open-cell foam dries to a softer and more flexible consistency. It is less effective at insulating and therefore a thicker layer would be needed to provide the same level of insulation as closed-cell foam.

Why is spray insulation popular?

Spray insulation has grown in popularity for several reasons.

Being a liquid spray means it can be applied to areas that would be difficult to reach with other, more traditional types of insulation.
Its dense structure means it can be applied in a thinner layer than more traditional insulation, such as mineral wool or glass wool. This thinner layer of insulation means more usable space in your loft, which can be useful for storage.
It was included in the Government’s Green Home Grant scheme. The scheme provided vouchers that covered up to two-thirds of the cost of getting certain energy-efficient home improvements made. The scheme ended in 2021.

How much does spray foam insulation cost?

You can expect your spray foam insulation cost to be higher than more traditional insulation materials.

On average, you can expect to pay £20-£50 per square metre. This means a typical 3-bedroom semi-detached property would cost around £2,500, compared to £600-£1,100 for more traditional insulation for the same property.

Is spray foam insulation good for your property?

Spray foam offers high levels of insulation and soundproofing. This means it can be a good choice for a number of different tasks, but there are also some concerns about it being used in areas of the home where it can cause damage.

Is spray foam insulation safe?

The chemicals used in the insulation are toxic. Homeowners are usually asked to vacate the space for 24-72 hours after any work has been carried out, but a professional installer can give you more specific safety information relating to your home.

Spray foam insulation problems

Problems with the insulation first came to light last year. Homeowners began reporting that insurance companies were refusing to cover their properties and mortgage lenders were refusing to lend on homes with the insulation.

What’s wrong with spray foam loft insulation?

Whilst it is an effective insulating material, its structure prevents the movement of air and moisture. This means that any condensation can get trapped in your loft space and cause damage to the structure of your roof. When the foam hardens, it can also cause wooden roof beams to warp.

The other problem is that the spray-on nature of the product prevents surveyors from being able to adequately assess the structure and condition of the roof. This makes surveyors, insurers and mortgage lenders very cautious.

Impact of spray foam insulation for homeowners

Using the insulation in your roof or loft space can result in:

Your property being difficult to sell
Difficulty re-mortgaging or releasing equity from your home
Structural damage to the roof of your property
Warped wooden beams
Damp and mould

Should I buy a house with spray foam insulation?

If you’re considering buying a property with sprayed foam insulation, you may want to take some time to consider your options. If you need a mortgage, you’ll also need to find out whether your lender would be willing to provide a mortgage for the property – some have a blanket refusal policy that prevents them from lending on any property with the insulation in the roof space.

Questions to consider if you’re thinking about buying a property with spray insulation

Can you get a mortgage for the property?
If you’re a cash buyer, will the insulation impact your ability to re-sell the property in the future?
Has the insulation done any damage to the structure of the roof?
Does the property asking price reflect the impact spray insulation has on property value?

Is spray foam making homes unsellable?

You may have seen worrying headlines like ‘spray foam insulation makes home unsellable’. But is there any truth to those articles?

In April 2023, the Government investigated claims that homeowners were having difficulty selling or remortgaging after having the insulation put in their homes. Their investigation sought advice from several key organisations such as the Royal Institution of Chartered Surveyors (RICS) and the Home Owners Alliance (HOA). RICS have said that the presence of the foam may impact their assessment of a property’s value and potentially make it unmortgageable, and HOA have advised anyone considering spray foam insulation to avoid it until the current issues are resolved.

What can you do if you already have the insulation in your house?

If you already have insulating spray foam in your property, you may be feeling quite worried. There are several steps you may want to consider.

Gather any paperwork relating to the installation

This will help if you come up against any problems selling, insuring or remortgaging your property. Gathering any relevant paperwork will show that you’re being proactive in your approach and will help any interested parties to make an informed decision, with a thorough understanding of the work that has been carried out at the property.

Explore other lenders

You might be able to avoid mortgage problems by looking at other lenders. Some lenders will be more willing to consider lending with foam insulation than others.

Removing insulation

Insulation removal can be difficult and costly, but may be worth considering if the insulation is jeopardising your sale or remortgage. You can expect to pay around £40 per square metre for removal.

What’s the answer for the insulation industry?

The Property Care Association has called for framework to ensure that the insulation is applied correctly and only to appropriate properties. They suggest that if the insulation is installed correctly, by qualified professionals, there shouldn’t be any need for concern.

RICS recommends that any homeowners considering the insulation seek independent expert advice – separate from any installer or manufacturer of insulation products – regarding its suitability for your property and any impact it might have on the value and saleability of your home.

Should I use spray foam insulation in my home?