Cavity Wall Insulation
Created 22Dec2023, Last edited 05Jan2024
Google: cavity wall creates dampness
https://www.which.co.uk/reviews/insulation/article/cavity-wall-insulation/cavity-wall-insulation-damp-problems-a5QkW7q4Hi8f
22Dec2023
Updated: 16 Nov 2021
Cavity wall insulation: damp problems
The results of our investigation into cavity-wall insulation inspections. Plus find out whether your home’s at risk of getting damp if you get cavity-wall insulation.
In this article
Cavity walls and wind-driven rain
Cavity-wall insulation secret filming video
Checklist: is my home at risk of damp problems?
Cavity wall insulation can cause damp. Find out if your home's likely to be affected.
When we went undercover to investigate the quality of insulation suitability inspections in 2011, our findings suggested that you can’t always rely on assessors to carry out thorough inspections or warn of potential damp problems – even those from big brands such as Marks & Spencer, Npower and Tesco.
Our video footage below shows the poor advice we received, and reveals some staggering price differences.
Cavity-wall insulation secret filming video
Checklist: is my home at risk of damp problems?
Cavity-wall insulation causing damp is very rare, but it’s worth checking whether your home’s at risk. You can use the checklist below to assess your home’s damp risk. Ask any potential installer about these factors, too.
Damp could occur in properties as a result of cavity-wall insulation if there is a combination of these factors:
* Your home is exposed to severe levels of wind-driven rain (zones three or four in our map below)
* Your home is located in an unsheltered position, eg not protected by trees or other buildings
* The external walls are poorly built or maintained with, for example, cracks in the brickwork or rendering.
Published guidance by the Building Research Establishment says that in these cases there is ‘an increased risk of rain penetration if a cavity is fully filled with insulation’. Rain could penetrate the outer wall, bridge the cavity via the insulation material and transfer moisture to internal walls, causing damp.
If you are in any doubt as to what kind of damp you have, see our advice on what kind of damp is affecting your home.
To solve any damp issues caused by cavity wall insulation in your home, you can use our Which? Trusted Traders service to find reliable, local damp proofing and insulation specialists in your area.
All of our accredited traders are thoroughly vetted by ex Trading Standards professionals and reviewed by their customers, helping you to make informed decisions about who you hire.
You can also use our Which Trusted Traders search tool to find traders near you.
Cavity wall insulation for a detached property £3,200
This site gives quotes also. After using MyBuilder to share your job for free.
Most expensive foam, then polystyrene beads then mineral wool.
Polyurethane foam 0.030 W/mK (best insulation)
Polystyrene beads 0.034
Mineral wool (Rockwool) 0.034 to 0.040
Once you have cavity wall insulation, you’ll save around £400 on average on your energy bills each year. If you spend £2,000 on the insulation installation, the cost will have paid itself off in five years.
https://www.mybuilder.com/pricing-guides/insulation-costs/cavity-wall-insulation-costs
Prior to the Mineral wool installation your cavity must be inspected, cleared and cleaned for this type of insulation material. The clearing of your cavity wall can be pretty expensive.
Mineral wool isn’t suited to a small cavity space, this means if your home hasn’t got enough room in its cavity walls, the installation of this material will do more damage than good!
Expanded PolyStyrene beads (EPS) with a bonding agent recommended.
£10-15 /m2 + Labour extra
A clean, spacious cavity is needed for installation.
Cavities can get very dirty and gritty over time. If you’re having EPS installed, it is so important to ensure the cavity is cleaned prior to the installation, this can be quite costly, depending on the state of the cavity.
If the cavity is not cleaned before EPS is installed, you may be facing the consequences of a failing cavity wall insulation!
Without the bonding agent, the beads will also lose some of their water resistant properties, this means dampness in your home is a possibility!
https://firstchoiceenergy.co.uk/cavity-wall-insulation-removal/insulation-material-pros-cons/
if your cavity is less than 50 mm in width, forget about it!
most are 50 to 7 5mm
Scaffolding needed.
I’m sure you’re aware that you can’t fill, or ‘top up’ a cavity that’s already been insulated, it can void your insulation guarantee provided by CIGA!
https://firstchoiceenergy.co.uk/eco-grants/cavity-wall-insulation/your-unbeatable-guide-to-cavity-wall-insulation/
Is my home suitable for cavity wall insulation?
https://firstchoiceenergy.co.uk/cavity-wall-insulation-removal/suitable-properties-for-insulation/
https://energygrants.org.uk/insulation/cavity-wall-insulation/
GR pd 851312 11Dec2023
The insulation materials used are usually mineral wool or polystyrene beads, although polyurethane foam may sometimes be used instead.
https://ecohomeuk.co.uk/professional-cavity-wall-insulation-installation-extraction/
info@ecohomeuk.co.uk
While houses built from the 1990s onwards generally have wall insulation, older homes may not have any at all.
The life expectancy of the insulation is 25 years. However, there are many examples of where the insulation has lasted longer than this.
1990 + 25 = 2015
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Cavity insulation is worth it - if it can be done properly. My parents, each winter, kept saying how cold their bedroom was each winter. Their bedroom has 3 outside walls with no cavity. It is a 100+ year old three-storey house. Two months ago I kinda went ballistic and stripped the entire room to the brick, created a cavity and put Kingspan insulation on the walls. I used foam insulation all along were the wall meets the ceiling, boarded and plastered, and fitted a new vent. Now they sleep with the bedroom door partially open and sometimes the window also and they say its too hot.
(PS I am not an insulation installer. Have had it done and regard it as NOT a waste of time/money. Also I do not read the Sun or Star.)
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