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Spray Foam Insulation vs Traditional Insulation

Author: Jack Lloyd
Updated: Dec 19, 2023
14 minutes read

Spray foam insulation, also known as spray foam or spray polyurethane foam (SPF), is an alternative to traditional insulation.

Although traditional insulation has many benefits, spray foam is versatile and can be used to insulate your roof, loft, walls and floor, helping to prevent heat from escaping and reduce energy costs. It can even increase your property value which we explain below.

Spray foam insulation and traditional installation

What Is Spray Foam?

This is liquid insulating foam that, when applied, sets to form a thermal barrier. It can be used to insulate several areas of the house such as roof, loft, walls, floors and more.

Having been around for over 30 years, spray foam is becoming increasingly popular as it’s an effective insulator that can also stop air leakage.

It's great for hard to reach areas as well as provide additional sound proofing and has an airtight seal that prevents heat loss but all the benefits are explained below.

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

Types of Spray Foam Insulation

Usually both open cell and closed cell spray foam insulations are made from polyurethane and filled with bubbles of gas or air, but have different properties when they are set. If you'd like to learn more about different types of loft insulation, see our article.

We explain both types below.

Closed Cell Spray Foam

Closed cell spray foam sets into a stable solid, which could help support the structure of your property if it’s not in the best condition. However, closed cell spray foam should not be used as a quick fix on structural repairs and should be taken care of properly.

When it sets, it contains lots of pockets of gas which slow down the movement of heat passing through it.

But it also acts as a barrier to moisture, so you’ll need to make sure the area has plenty of ventilation. Otherwise condensation could build up.

Open Cell Spray Foam

Open cell spray is less dense once set so you’ll need to install a thicker layer to get the same level of insulation as closed cell.

Open cell spray foam is often used for soundproofing as it blocks and reduces airflow. It allows moisture through it so there’s less risk of condensation building up.

Pros and Cons of Spray Foam

Spray foam insulation offers a range of benefits such as:


  • It can be applied in hard to reach areas

  • It can provide additional sound proofing

  • Airtight seal prevents heat loss

  • Seasonal energy bills are decreased

  • Home energy efficiency is increased

  • Ideal for lofts, roofs, walls and floors

  • Air leakage is virtually eliminated


  • It needs to be installed by a professional

  • It can be difficult to remove once it's been installed

  • Harmful fumes are given off during installation

  • Not to be used in listed buildings or houses with thatched roofs

How Much Does Spray Foam Insulation Cost?

There are many factors that might determine how much you pay to have spray foam insulation installed in your home or business premises. These include how much spray foam insulation you need, which parts of your building need to be sprayed, how big your property is, how long the job will take and so on. The thickness of your spray foam insulation may also affect the cost, as can the type of spray foam insulation you opt for. The two main kinds of spray foam insulation available to you are open cell and closed cell.

Can Spray Foam Insulation Add Value To Your Home?

There’s a big chance spray foam insulation could increase the value of your home. This is because homes with good insulation tend to be more in-demand. Over half of all property purchasers now consider energy-efficient as important when they’re looking for a new home or business premises.

If you don’t have any insulation, or if your home is poorly-insulated, you could be paying much more for your fuel bills than you need to. It’s said that uninsulated homes lose around 40% of heat during the winter months. This causes your HVAC systems to work harder, which in turn leads to a rise in energy bills.

How Much Can Spray Foam Insulation Reduce My Energy Bills?

Spray foam insulation could help cut your energy bills by approximately £45 each month, a figure that equates to over £500 each year. Although the price that you initially pay for spray foam insulation may seem large to some, you start to get your money back over time thanks to the way the insulation can help you reduce your energy bills. Spray foam insulation can last for more than 20 years, so you can expect to see a good return on investment.

Traditional Insulation Types

To get an idea on traditional insulation types and how they compare against spray foam insulation, we’ve listed them out below:

  • Fibreglass Insulation

  • Cellulose Insulation

  • Celotex Insulation

  • Rockwool Insulation

Fibreglass Insulation

Fibreglass is one of the cheapest insulation methods, whilst providing similar qualities to some of the pricier alternatives.

It comes in two options, blankets and loose fill and this insulation has been popular in the homes around the UK.

Pros of Fibreglass Insulation

  • Fibreglass is a cheaper insulation choice

  • It doesn’t shrink

  • It's environmentally friendly, using recycled glass

  • It has a U-value of 0.3

Cons of Fibreglass Insulation

  • Fibreglass blankets struggle to cover all gaps

  • Fibreglass contain harmful glass particles that can cause irritation

Cellulose Insulation

Cellulose insulation consists of cellulose cells that have natural insulating power. It is made of shredded paper and a chemical known as a borate. The paper is broken down into cellular fibres which then provide insulation.

This insulation is installed in your loft using an insulation blower and sprayed into your loft space.

Pros of Cellulose Insulation:

  • Cellulose is environmentally friendly

  • It is more efficient than Fibreglass

Cons of Cellulose Insulation:

  • Cellulose insulation can be very messy when applied

  • It requires a lot of space for installation

  • Cellulose insulation often has issues with moisture

Celotex Insulation

Celotex is a hard insulation product made by gluing the laminated aluminium foil facings together.

The insulation boards have improved thermal performance compared to other traditional insulation products making them a desirable form of insulation.

The product is lightweight and easy to apply.

Pros of Celotex Insulation:

  • Celotex has a good thermal performance

  • They don’t absorb water

  • Celotex doesn’t absorb moisture or sag

Cons of Celotex Insulation:

  • Celotex doesn’t fill in all the gaps

  • It isn’t airtight

  • Possibility of it falling out

  • Not very flexible

Rockwool Insulation

Rockwool insulation, also known as mineral wool, comes in easy to install batts similar to fibreglass. Rockwool is composed of rocks that are heated until they melt into a liquid and exposed to high pressure and then spun into long fibre strands at high speed.

Pros of Rockwool Insulation

  • Rockwool is fire resistant

  • It has excellent thermal insulating properties

  • Rockwool is breathable

Cons of Rockwool Insulation

  • Rockwool can cause skin irritation and respiratory problems if breathed in

  • Possibility of it starting to sink and sag over the years

  • Will not dry easily if it becomes damp or wet


Hopefully this guide has now given you an in depth look into both spray foam and traditional insulation. Although traditional can help in a many ways, spray foam insulation can often be the better alternative and has a wide range of benefits:

  • Spray foam insulation can be applied in hard to reach areas

  • It can provide additional sound proofing

  • Airtight seal prevents heat loss

  • Seasonal energy bills are decreased

  • Home energy efficiency is increased

  • Ideal for lofts, roofs, walls and floors

  • Air leakage is virtually eliminated

As you can see, spray foam insulation has so many things going for it. If you would like to invest in spray foam and would like to talk to a professional, just enter a few details and we will take care of the rest.