How Much Does Cavity Wall Insulation Cost?

Written by Daniel Woodley. Fact checked by Hannah Miller. Published to Prices. Updated on the 4th March 2023.

Our editors publish helpful guides and insights learnt from years of experience and recent research. They also test, review and suggest home and garden products. If you buy something via links, we may earn a commission, but we never accept products or incentives from manufacturers. Learn about our process.

Most of us know what cavity wall insulation does – it’s a filler injected into the space between the inner and outer walls, keeps our homes warmer, and helps reduce our heating bills.

This stuff has been in the news for decades and most of us have at least heard of it before.

But how much does cavity wall insulation really cost to install in a typical house?

What is the average cost per square metre?

Does the government still offer discounts?

About These Prices

I recently managed a renovation project on a property, and I gathered prices from cavity wall insulation firms.

The prices shown below are:

• Based on prices I sourced from 24 cavity wall installers that gave me prices in January 2023.
• For EPS beads – one of the most popular types of cavity wall insulation.
• Exclude government or energy supplier discounts.
• Exclude scaffolding, as it wasn’t needed on my project.
• Includes VAT if it was charged by the installer.

As the figures below are an average of the prices given to me when I gathered quotes, I believe they’re an excellent guide to the going rate for cavity wall insulation in the UK:

Cavity Wall Insulation Price Per Square Metre

The average cost per square metre of wall, excluding windows and doors, came in at around:

£20 per square metre.

Cavity Wall Insulation Prices Per House

While I only sourced prices for cavity wall insulation to a 3-bed semi-detached home, we can use the “per square metre” figure to easily calculate the cost for other homes:

1 or 2-bed small mid-terrace or corner house: £1000

1-bed end of terrace: £1200

2-bed end of terrace/small semi: £1400

3-bed semi: £1600

2-bed detached: £1700

3-bed detached: £2000

4-bed detached: £2500

4-bed large detached: £3000+

Government-Backed Discounts and Schemes

Over the years, I have seen various green schemes come and go, and the most recent – The Green Homes Grant – ended on the 31st March 2021.

In the UK, energy companies offer heavily discounted or free insulation to homeowners and some private tenants, provided that at least one person in the home receives certain benefits.

This is part of the ECO scheme, backed by government legislation.

I’ve looked into this, and you’ll need to contact your energy supplier for more details if you believe you may qualify.

I’ve seen plenty of marketing scams around; some firms or intermediaries offer fake discounts that reduce already inflated prices, so watch out for random offers from firms you’ve never heard of before.

As of 2023, I feel your best bet is to contact your energy supplier and see if they can offer you a discount but do also get separate quotes for comparison.

Which Type of Insulation is Best? – My Opinion

I previously project managed a renovation where the fibre cavity insulation was wet and had caused damp and mould damage to the property – the level of damage, and the cost to carry out the repairs were significant.

I know from experience that EPS beads (polystyrene balls) are one the best options as they’re least likely to cause damp problems.

Should you be worried about potential damp?

Well, yes, there is a genuine risk of the insulation getting wet and damp penetrating into the home.

This is more likely if:

• Your wall is in an exposed location that gets lashed with rain.
• The brickwork is in poor condition, cracked or has missing or degraded pointing.
• You haven’t treated your external walls with a brick sealer.

While EPS beads are least likely to cause damp problems, no type of insulation should ever be put into cavities where the walls are in poor condition and/or in windswept locations.

Beware of Mis-Selling: I’ve Seen it Several Times

There are plenty of homes in the UK that should never have cavity wall insulation fitted.

In fact, one MP described the mis-selling of this insulation as the next PPI scandal.

In short, if you live in a windswept location, i.e any part of west Scotland, west Wales or the south-west, any coastal area or any elevated area, cavity wall insulation might not be for you.

But don’t assume that every cavity wall insulation company will tell you that. I’ve seen first-hand and heard of reports of some firms doing whatever it takes to get the sale – this industry is rife with mis-selling.

I’ve personally met several homeowners who have had problems with damp, and I’ve worked on one property where we brought in a firm to remove it.

Please forgive me if I come across as negative, most of you reading this guide will benefit from cavity wall insulation, and I have it in my home; I’m just wary of mis-selling as I’ve seen the consequences. If you do your homework and get quotes and advice from several installers, I’m sure you’ll be fine.

Cost to Remove Cavity Wall Insulation

Problems with damp cavity wall insulation can be devastating and the repair bill can run into the tens of thousands.

Due to widespread mis-selling, there is now a new industry – cavity wall insulation removal services – and it’s a popular business model.

I’ve even used the services of one of these firms before – they have huge hoovers that suck out the insulation.

On this page, I take a look at how much it costs to remove damp cavity wall insulation in the UK.

Get a Custom Price for Cavity Wall Insulation

Tap the button below to arrange a custom quote for your cavity wall insulation.

• Only takes minutes online.
• No obligation.
• Read reviews from past customers.

Why You Can Trust This Guide

The advice on this page is based on years of experience within the home improvement sector.

However, the price guide was created by our researcher, Daniel, who contacted cavity wall installers and asked for prices.

The figures are an average of the prices supplied.

Note: Cavity beads are made from plastic, and the cost of plastic is loosely related to the cost of oil, which is currently volatile.

Turfing Cost

We’ve researched how much turfing costs and on this page, you’ll see how much professionals charge per square metre.  Start Here