Can Expanding Foam Be Used as Insulation?

expanding foam insulation

Imagine an insulation solution that fills every nook and cranny, weatherproofs them, and seals the gaps effortlessly. That’s the magic of expanding foam! But what about using it for larger areas of your house? Can expanding foam be used as insulation?

In this article, we’ll discuss the properties and benefits of expanding foam. From energy-saving to fire-proofing, keep reading for all the details!

Can Expanding Foam Be Used as Insulation?

Yes! You can use expanding foam as insulation. In fact, the spray product is one of the best insulation options on the market compared to other types.

For those wondering, expanding foam, or spray foam, is an insulating plastic made of polyurethane and isocyanates. These chemicals are kept in two separate tanks. After heating and pressurising the liquid components, they meet at the spray gun’s tip. 

Once you pull the trigger, these materials react, expanding into the insulating foam.

This reaction helps the spray foam cover large surfaces and reach the tiniest nooks, resulting in efficient insulation.

How Good Is Expanding Foam Insulation?

Thanks to its unique properties, such as high thermal resistance and durability, expanding foam stands out as one of the most effective insulation solutions. This product helps you save energy, control moisture, and limit mould growth, among other perks!

Here’s why expanding foam is a good choice for insulation:

  1. Energy Saving

As you know, saving energy is the whole idea behind using insulators. Spray foam is thermally resistant, boasting an R-value of 3.5 to 7 per inch, depending on its type.

In case you’re wondering, the R-value measures a material’s insulation efficiency. The higher the value, the better the compound stops heat flow.

Compared to other insulators in the industry, spray foam has one of the highest values, all thanks to its structure.

That helps prevent air infiltration, reducing the workload on your heating, ventilating, and air conditioning systems. As a result, it can help you cut down on your energy bills by around 35%!

  1. Moisture Control

While the foam’s components aren’t waterproof, expanding foam can help shelter your house from high humidity problems. However, that depends on the foam’s type.

Expanding foams can have an open-cell or closed-cell structure. The former is flexible due to its wide pockets, making it semi-permeable to water and air.

Closed-cell spray foam, on the other hand, has a compacted structure. It can restrict small vapour molecules from seeping into the insulated surface. Consequently, it’s an excellent choice if you live in a humid climate and want to prevent dampness.

  1. Air Sealing

Similar to moisture control, expanding foam has air-sealing properties. Again, this has to do with its cellular structure. Thanks to its expansion, this product can reach nooks and crannies, sealing those gaps.

Not only does that help you save energy, but it can also add structure and integrity since the product is highly adhesive and rigid.

Aside from that, expanding foam can also help with soundproofing, preventing external noises from disturbing your peace!

  1. Mould-Resistant

As mentioned earlier, expanding foam helps with moisture control. That can be handy in preventing mould growth.

Those slimy creatures flourish in humid conditions. While they pose many environmental benefits, indoor moulds cause several health problems. Plus, they can cause building materials to rot and deteriorate.

Spray foam can help you tackle this issue. This chemical compound lacks nutrients. So, there isn’t any organic material for the mould to feed on.

However, the expanding foam is only helpful after you address the primary issue of dampness—sealing wet walls with insulators won’t cut it.

  1. Fire-Proofing

Polyurethane and isocyanates aren’t the only components of spray foam. Other chemicals, like flame retardants, also go into the mix. That’s because foam, in and of itself, is flammable, like most plastics. It’ll burn quickly when exposed to heat.

So, to prevent fire hazards, spray insulation contains fire-retardant substances. Additionally, an intumescent coating is usually painted over the foam. Sure, that won’t make the layer fire-resistant, but it’ll help stop flare-ups from spreading rapidly.

  1. Long Lifespan

With all those features, you can expect expanding foam to be on the expensive side. The good news is that this insulator is highly durable. It can resist heat, chemicals, and moisture, lasting up to 100 years. So you don’t have to worry about costly maintenance and repairs.

However, that’s as long as you keep the foam away from UV exposure. Although its components are durable, polyurethane is sensitive to radiation. Over time, the light will wear it down.

Where Not to Use Expanding Foam as Insulation?

From the above, you can see that expanding foam is versatile, and you can use it on walls, lofts, and floors. Still, this insulating product isn’t suitable in some places, like damp walls.

Let’s explore where you shouldn’t install expanding foam in further detail!

  1. Damp Walls

This one might be confusing since expanding foam is semi-impermeable and can prevent water from reaching the covered area. However, if your house has a condensation issue, spraying insulating foam will make the situation worse.

For starters, the foam won’t cure and adhere to the surface well, losing its energy-saving properties.

Additionally, the layer isn’t breathable, so you’re only sealing in moisture, allowing mould to grow and cause rot.

  1. Cold or Warm Areas

Like moisture, temperature also plays a role in expanding foam’s adhesion. As a rule of thumb, most spray foams adhere well to substrates with a temperature between 15ºC and 27ºC.

Unless the product specifies it’s for lower or higher temperatures, the insulating layer won’t be effective outside this range.

  1. Around Electrical Boxes

You should avoid using spray foam near utility boxes. Likewise, avoid spraying it near lamps or any place with high temperatures. That’s because such electrical devices are a fire hazard.

While spray foam contains fire retardants, the product still emits volatile organic compounds. Not only are such gases toxic, but they’re also flammable.

Aside from that, you risk damaging all the wires and cables if the foam cures around them.

  1. Near Leakage

Sure, spray foam is excellent for air sealing, as it reaches even the toughest cracks. However, that doesn’t mean you can use it to stop leakage. That’ll only worsen the problem. The water will still spread through the walls, causing moisture-related issues.

  1. Listed Buildings

Spray foam insulation and listed buildings aren’t a perfect match. For one, these buildings are old. So, they can have several structural issues besides dampness. Expanding foam will only add fuel to the fire.

Even if the historic building is in tip-top shape, you need to obtain Listed Building Consent to do any construction work. In most cases, you won’t get their approval.

  1. Houses on the Market

As surprising as it may sound, you should avoid expanding foam insulation if you plan on selling your house. That’s because faulty installation can negatively affect your property’s value. Plus, homes with foam insulation might not be eligible for mortgages.

Expanding foam insulation conclusions

As you can see, expanding foam is a versatile, effective insulation solution. It boasts energy-saving, moisture control, air sealing, mould prevention, and fire resistance qualities.

Aside from that, its durability and long lifespan make the foam suitable for many applications, including insulating lofts, walls, and floors.

That said, it’s important to use this insulating material wisely, avoiding damp walls, extreme temperatures, and utility boxes, among others.

With proper use, expanding foam can offer remarkable insulation properties, ensuring your home remains comfortable and energy-efficient for many years to come!

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