Open Cell Spray Foam Insulation

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There are plenty of reasons why homeowners are installing insulation in their droves and why political activists are lobbying the government to insulate the UK. Insulation comes with a wealth of benefits for residential homes and commercial buildings alike. 

But here’s the thing. Not all types of insulation are created equally. Some types of insulation are more effective at preventing heat from escaping, while others offer benefits such as fire safety or even noise reduction. 

Spray foam is a well-known type of insulation that’s been used traditionally in spaces like lofts and cavity walls. There are actually two types of spray foam – closed cell and open cell – and in this post we’ll explore the latter, looking at what open cell spray foam is, its advantages, and its drawbacks.

What is Open Cell Spray Foam Insulation?

Spray foam, also known as spray polyurethane foam, is a type of insulation that is sprayed into a certain area and then expands to fill the space. The result is insulation that fills almost every crevice and has a cloud-like appearance, although the texture is much more solid than traditional foam. 

There are two types of spray foam – closed cell and open cell. Closed cell spray foam is dense and solid, and you don’t need a particularly thick layer to see effective results in terms of increased thermal efficiency. As the name suggests, it’s made up of entirely closed components, which result in the density. 

It’s thanks to this density that closed cell spray foam is able to insulate your property so effectively, almost entirely trapping heat without gaps to allow it to escape.

where can spray foam be used

Open Cell Spray Foam vs Closed Cell Spray Foam

Both open and closed cell spray foam have similar advantages and disadvantages, but there are some clear distinctions that differentiate the two. Closed cell is a more rigid solid and much denser than open cell. That means to achieve a layer of insulation that’s as effective as closed cell, you’d have to install more open cell spray foam. 

Although closed cell is pricier than open cell, the extra layers of open cell you’d need to install somewhat cancel out these cost savings. 

Closed cell spray foam is considered a better insulator than open cell because it does a better job of preventing heat from escaping thanks to its density. Unfortunately, this also acts as a barrier to moisture, which can cause damp issues. 

While open cell spray foam might not be quite as good at preventing heat from escaping, it’s a great form of acoustic insulation, significantly reducing the noise from neighbouring properties or other rooms in the home. 

There’s no one better option than the other – both have their benefits and drawbacks. If you’re concerned about damp or noise reduction, open cell might be a better option, while closed cell is the obvious choice if improving thermal efficiency is your number one priority. 

The Benefits of Open Cell Spray Foam

Here are just some of the advantages you can expect to enjoy when you install open cell spray foam. 

Maybe you have a noisy neighbour or your teenager’s new band has decided to start practising in your attic. Whatever the reason, if you want acoustic insulation as well as thermal insulation, spray foam does both jobs without you having to buy two different materials. 

Open cell spray foam is much better at soundproofing than the closed cell alternative, so bear this in mind if noise reduction is one of your priorities.

Because spray foam is so effective, you don’t need as much to insulate your home successfully. While you will need slightly more open cell spray foam than you would closed cell, you can still get away with a thinner layer. This means you’ll have more space left in your loft for storage than you might with alternative insulating materials. 

Spray foam in any form is one of the most expensive types of insulation on the market. Open cell spray foam, however, is cheaper than closed cell, so if you want to use spray foam in your property, open cell is the more budget-friendly option. 

The main purpose of insulation is to prevent heat from escaping, and both open and closed cell spray foam achieve this objective very successfully. 

Many insulation materials can either leave huge gaps and air leakages, which make them ineffective, or settle and compress over time. With open cell spray foam, it expands to make an airtight seal, preventing any air or moisture from escaping the area. 


While it’s true that open cell spray foam is much cheaper than the closed cell alternative, both types of spray foam insulation are more expensive than typical insulating materials, such as fibreglass or blanket insulation. 

Also, while closed cell spray foam does a good job of preventing leaks from getting through the insulation, this can actually stop you from realising when there’s a leak in your home. Other insulation materials would show immediate damage from a leak in the home, but with closed cell spray foam, it’s more likely to go unnoticed.

While not strictly a drawback for everyone (some DIY-phobes would dread having to install insulation) spray foam has to be installed by a professional contractor using specialist equipment. 

This means the material is unsuitable for a DIY installation, so it’s very tricky to save money on the labour costs associated with spray foam.

Whether it’s past its best or you need to remove spray foam because it’s causing issues in your home, it can be extremely difficult to remove and is a job for professionals. Taking the decision to install spray foam insulation shouldn’t be taken lightly because it’s difficult, expensive, and time-consuming to reverse if you change your mind. 

Spray foam insulation can release harmful fumes during the installation process. While you should never be installing spray foam insulation yourself anyway (it’s a job best left to the pros), it’s still something to bear in mind as a potential health hazard associated with this type of insulation. 

The Relationship Between Open Cell Spray Foam and Property Values

Here’s where things get a little more complicated with spray foam. Spray foam has been installed in homes for over 30 years now, but in recent decades there have been worries about the safety of spray foam in the home. 


Because spray foam insulation creates such a tight seal, much more heat is kept in, and there’s a lot less ventilation than you might experience with other forms of insulation. Unfortunately, by retaining so much heat with little ventilation, spray foam can create the ideal environment for damp and mould to flourish. 

Not only are damp and mould terrible for the health of the home’s residents, but they can even rot the roof timbers, leading to long-term damage to the property’s structural integrity. 

As a result, some lenders refuse to give mortgages for homes that have spray foam insulation fitted and some valuers will reduce the value of a home if they find spray foam during a survey. 

Lenders and valuers are working with the spray foam industry to solve this problem, but it does mean you should think twice about getting spray foam insulation installed just before you plan on selling a house. Luckily, open cell spray foam allows your loft space to ‘breathe’ more effectively, so it doesn’t experience as many damp issues as the closed cell alternative. 

That being said, it’s still worth checking with an expert before you have this insulation installed and make sure you get all the necessary paperwork if you decide to go ahead.

How Much Does Open Cell Spray Foam Cost?

Spray foam is one of the most expensive types of insulation on the market, but open cell is the cheaper option out of the two. While spray foam in general varies from around £20 to £50 per square metre, open cell spray foam is at the lower end of that price range. 

On top of the price of the material, you’ll need to consider labour costs, too. Unfortunately, there’s no option to install spray foam yourself, so you’ll need to call in the pros for this.

You can expect to pay up to £350 for an installer to visit your home and fit open cell spray foam insulation, and this price will vary in part as a result of where you are in the country. The southeast is much more expensive than the north, for example. Luckily, open cell spray foam shouldn’t take more than one day to install, provided that you’re not insulating your entire home. 

If you’re looking for a more budget-friendly alternative, blanket insulation (which comes in rolls, slabs, and batts) is significantly cheaper. Plus, it can be installed as a DIY project.

The downside of blanket insulation is that it’s not great for hard-to-reach spaces or inaccessible lofts. In that situation, loose-fill is a better alternative to spray foam as it can be blown into small spaces using specialist equipment.

Where to Find an Open Cell Spray Foam Installer

There are plenty of things to consider before going ahead with open cell spray foam insulation. While the advice is currently mixed on the impact of spray foam on property values, it might be worth pursuing a different type of insulation if you plan on selling your home in the near future. If you’re happy to wait for the dispute to be resolved, then installing spray foam to enjoy its range of benefits might work for you. Ultimately, it’s your call.

If you’re set on installing spray foam, working with a trustworthy installer is key. Luckily, we know just where you can find one of those! Using our contractor finder tool, you can access quotes for insulation from installers that cover your area. If you need more information, check out online reviews and testimonials or ask them for qualifications or examples of previous work. 

Experienced installers will be able to accurately assess your space and establish whether spray foam is suitable. If it isn’t, an expert installer will help you find an appropriate alternative.

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