Closed Cell Spray Foam

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Spray Foam Insulation comes with many benefits, including reduced energy bills, a warmer home, and more.

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Insulation can be a game-changer for people looking to boost their eco credentials, save money on their energy bills, and keep their house warmer in the winter and cooler in the summer.

Insulation can be installed in various parts of the home, such as your walls, roof, floor, and loft space. It works by trapping heat in a space, which either stops it from leaving your home (in the winter) or stops it from making your home even hotter (in the summer).

Spray foam insulation is a well-known type of insulation that’s incredibly effective at making your home more energy efficient. This doesn’t mean, however, that spray foam is without some issues, which we’ll explore later.

But if you’re curious about how spray foam works and are considering it for your home, it’s worth understanding the two different types of spray foam insulation currently available – closed cell spray insulation and open cell. Let’s dive into closed cell spray foam, what it does, how it works, and the advantages and disadvantages of this popular material.

What is Closed 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 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 results in the density.

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

what is spray foam insulation

How is Closed Cell Spray Foam Insulation Installed?

Two pipes channel two materials into a spray nozzle, which mixes the elements together. You then point the spray nozzle at the space you wish to insulate, at which point the elements react and expand, filling the space until there’s a completely airtight barrier.

It’s worth noting that spray foam can give off harmful fumes during installation, so it should only ever be installed by professionals, and safety procedures should be followed as closely as possible during the process.

where can spray foam be used

Closed Cell vs Open Cell Spray Foam Insulation

Closed cell and open cell foam are the two spray foam options you can choose from when choosing to insulate your home with this material.

When the two materials are set, closed cell is more rigid, solid and denser, meaning you don’t need to apply a thick layer. Open cell foam insulation is less dense and while it tends to be less expensive as a result, you will need to apply a thicker layer, which may cancel out the cost reductions.

Closed cell insulation is a more effective insulator than open cell on the whole because the separate pockets of gas slow down heat’s ability to move through it. The problem with this density is that it’s also a barrier to moisture, which leads to one of the most commonly seen issues with spray foam insulation – damp.

If you opt for closed cell spray foam, having adequate ventilation in the space is a must. Open cell spray foam, on the other hand, lets moisture through, so doesn’t run as much of a risk of damp. It’s also an excellent form of sound insulation thanks to its sound-proofing capabilities.

On the whole, there’s no right or wrong choice when it comes to open cell vs closed cell – it depends on your needs. If efficiency is your number one priority, closed cell is the obvious choice, but you’ll need to insert some sort of ventilation into the space to avoid dampness.

If you can deal with a slightly less effective insulator to minimise the risk of damp and benefit from acoustic insulation properties, open cell might be the better option.

Where Can Closed Cell Spray Foam Insulation be Installed?

Closed cell spray foam can be used to insulate your loft, roof, floors, or cavity walls. It cannot be used to insulate solid walls, which require either internal or external wall insulation.

The Pros of Closed Cell Spray Foam

Closed cell spray foam is incredibly dense and doesn’t tend to leave gaps, meaning your space is insulated airtight with practically zero air leakage. While this can cause damp issues, it’s undoubtedly a very effective way to insulate your home and can achieve a higher level of thermal efficiency and even improves indoor air quality due to the air barrier its dense foam can create compared to traditional insulation materials.
Closed cell foam is an incredibly durable material, so you’re guaranteed a long lifespan once it’s been installed. This means you wouldn’t have to look at replacing the insulation for at least a few decades.
While the lack of permeability can create problems for condensation, there’s also a benefit to those who live in flood zones. Unlike some other insulation materials, closed cell spray foam isn’t prone to becoming damaged or weakened by water.
Spray foam insulation can keep your pipes warm and reduce the chance of them freezing during spouts of cold weather.


The density of closed cell foam is both its biggest strength and its biggest weakness. While it makes the insulation incredibly effective, it does mean that moisture also struggles to get through the material, which has the potential to cause damp, and eventually, mould.

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.

If you’re on a tight budget, closed cell foam probably isn’t the best insulation material for you. It’s one of the most expensive options on the market and since it has to be installed by a professional, you can’t even save labour costs by opting for a DIY installation.
If you decide you want to remove or replace your spray foam after having it for a certain length of time, it’s incredibly difficult to do so.

Spray Foam and Property Value

While installing spray foam insulation (both closed cell and open cell) has its advantages and disadvantages, there’s one significant drawback that’s worth considering before you install spray foam insulation, especially if you intend to sell your home in the near future.

There’s a tricky relationship between spray foam insulation and property value. Because of the risk of condensation and damp occurring because of spray foam’s density, there’s a risk of the damp eventually rotting roof timbers, which causes serious structural damage to a property.

As a result, some lenders are reluctant to offer mortgages on homes with spray foam and surveyors might even reduce the value of a property once they see that closed cell spray foam insulation is present in a property. The spray foam insulation industry is working closely with lenders and surveyors to try and solve the problem, but it’s worth keeping an eye on if you plan on installing spray foam.

For many, though, the benefits far outweigh the current arguments between the mortgage and insulation industries, but it’s still worth keeping this in mind.

How Much Does Closed Cell Spray Foam Cost?

Spray foam insulation is one of the priciest insulation materials on the market. For the material alone, you can expect to pay somewhere between £20 and £50 per square metre.

Closed cell tends to be more expensive than open cell because it’s more effective, but since installers usually use more open cell spray foam to make up for the lower R-value, you might end up paying just as much for the material.

In terms of labour costs, you’ll typically pay around £150-£250 per day for an insulation installer. Naturally, this will be more or less expensive depending on where you live in the country. The good news is, spray foam shouldn’t take more than an afternoon to install in your home, as long as the space isn’t too big.

If you work with Insulation Advisor, you can get up to £1,500 spray foam insulation voucher through our partners.

Can Closed Cell Spray Foam Be Used to Make a Warm Roof?

In a warm roof, the insulation is placed at the top of the loft in the roof rather than in the joists to keep the loft space warm so you can use it as a room rather than storage. Unfortunately, spray foam can’t be used as a way to create a warm roof. Rigid insulation boards are the insulation material most typically used for this type of loft space.

How to Find a Closed Cell Spray Foam Installer

While it’s true that spray foam can cause issues with your property value, it remains an incredibly effective form of insulation, with a high R-value and the ability to seal a space airtight without letting heat escape. If you plan on staying in the same property for a long time and therefore aren’t worried about the value of your property decreasing, it can be a good option.

If you’re looking to find an insulation installer in your area, it’s never been easier, with our contractor finder tool. Simply type in your postcode and you’ll gain access to quotes from a whole host of reliable suppliers and installers in your area. For added peace of mind, search for online testimonials and reviews or examples of previous work. You could even get an up to £1,500 spray foam voucher with some of our partners, making the installation even cheaper!

If you’re not interested in installing closed cell spray foam, you can find insulation installers for plenty of other types of insulating materials on our site, too.

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