Spray Foam Insulation

Is spray foam insulation a good fit for your home? Find out along with details of the costs, types and insulating properties.

Spray foam insulation, sometimes called simply spray foam, has become increasingly popular in the UK as an alternative to more traditional forms of insulation.

It’s a versatile material that can be applied to walls, floors, attics and lofts.

What’s In This Guide?

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What Is Spray Foam Insulation & Is My House Suitable?

Spray foam insulation (SFI) is essentially just a mixture of chemicals that expand and dry quickly when applied to a surface or area. And whilst these chemicals are not very eco-friendly, the foam’s high U-value will reduce your fuel bills and decrease your carbon footprint.

There are more than 40 companies with patented formulas operating in the UK alone some of which use soy or vegetable oil as the propellant and one which uses water. So there are some more eco-friendly options available.

Spray foam insulation is suitable for a variety of applications and situations and it’s high insulating properties mean that you can have the same level of insulation from a thinner layer.

SFI Types

Whilst each manufacturer uses different chemical mixes, there are two main types of spray foam insulation.

Closed Cell

More akin to the rigid foam boards that you see used in attics and walls, this type of foam once cured is less permeable and can provide structural support. It’s also more expensive because of the higher density of plastic needed in its creation.

Open Cell

Due to its composition, open cell insulation allows air and moisture to pass through it giving it, its reputation as a breathable solution. It’s also less rigid and more flexible making it suitable for a variety of situations.

The Insulation Process

  1. After the initial quote, a detailed onsite inspection of your property is carried out where the viability and price is confirmed.
  2. When the spray polyurethane foam(SPF) is being installed, you’ll have to vacate the house for 24 hours while the foam cures due to the toxicity of the off gassing.
  3. The insulation team will cover any fixtures, doors and windows with plastic as needed and use fans to facilitate ventilation.
  4. The spray foam is applied to all areas required where it expands up to 100 times its size filling all cavities and blocking any drafts.
  5. After the 24 hours, any danger from off-gassing will have passed and you can return to the house.

How Good is Spray Foam Insulation?

The effectiveness of an insulating material can be measured by it’s R-Value which measures the ability to resist heat transfer at a certain thickness.

Below we’ve collected the R-Values of a range of different insulators to give you an idea and help you decide on your investment.

So to answer the question, yes spray foam insulation is an excellent insulator, with closed cell mixtures the clear winners.

How Much Does Spray Foam Insulation Cost?

As a simple rule of thumb, spray foam insulation will cost between £25 to £65/m², depending on thickness and type spray foam insulation.  A variety of factors will effect the total cost of spray foam insulation including;

  • the type of foam and depth required
  • the m2 area you want insulated
  • the number of vent cards needed
  • additional equipment such as scaffolding

Don’t be surprised to get vastly different quotes from companies.

Spray Foam Home Insulation Grants

Grants are available for external insulation through the SEAI.

SFI: Considerations

Whilst spray foam insulation can be a great benefit to improving your home’s comfort level, it is an expensive outlay and there are some things that you must weigh up before choosing.

Cost: If you plan on moving home in the next few years, SFI might not make financial sense.

Existing Insulation: Getting SFI will improve your building seal but if it’s not applied as part of a greater plan to insulate your home, you will not see the full benefits.

Difficulty To Remove: SFI can be extremely labour intensive to remove.

Spray Foam Insulation: The Advantages

SFI is great for a number of reasons but here are the pick of the bunch.

The Disadvantages

But like all things in life, spray foam insulation is not without its drawbacks.

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Last Updated on October 28, 2021


Author: Indra Gupta

Indra is an in-house writer with a love of Newcastle United and all things sustainable.

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