Can cavity wall insulation cause health problems?

Author: Mr. Raven Franecki  |  Last update: Wednesday, June 11, 2025

If water and dampness remains in the cavity, this can lead to mould and mildew growth. Mould and mildew can cause a number of health problems, including respiratory problems and skin allergies.

Is cavity wall insulation bad for your health?

Blown fibre insulation

Although it has no health effects when fully sealed within the cavity, if it escapes through gaps it can be a bit of a nightmare. Although blown fibre insulation isn't classed as hazardous, it is an irritant – if it escapes, it can really itch your eyes and skin.

Why are people removing cavity wall insulation?

One of the main reasons as to why people decide to have their cavity wall insulation removed is because their property isn't suitable for it. For instance, if your property is often subject to wind-driven rain, then it is not recommended that a cavity wall is in place.

Do you need ventilation for cavity wall insulation?

Whilst cavity wall insulation itself does not require any maintenance, as with any building, failure to properly maintain the fabric of your house, inadequate ventilation or a lack of heating may result in problems with dampness.

What happens to cavity wall insulation after 25 years?

Cavity wall insulation usually lasts 25 years or more. Still, it may need replacement due to material degradation, moisture damage, structural changes, increased energy bills, or visible issues like dampness and mould.

Cavity Wall Insulation Problems ~ The Ugly Truth

What is the life expectancy of cavity wall insulation?

Most manufacturers offer a 25-year warranty, but the typical lifespan of cavity wall insulation is between 20-100 years. When installed correctly, cavity wall insulation is made to last the lifespan of your property. Unless damage occurs, all cavity wall insulation should last for up to a century.

Should I replace my cavity wall insulation?

There are several reasons why you may need to consider having your existing cavity wall insulation removed and replaced, including: Poorly installed insulation is now causing damp and or cold spots internally. The insulation has become defective or is unsuitable.

What houses should not have cavity wall insulation?

Properties without a DPC, or where the DPC is too low (typically less than 125mm from the ground) and a French drain has not been installed. Some properties with raked mortar joints. Properties with a cavity wall under 50mm or over 150mm. Properties that have significant rubble or mortar ingress in the cavity.

Does cavity wall insulation stop mold?

Cavity wall insulation can significantly improve energy efficiency in homes. However, if not installed correctly, it can lead to damp and mould issues. This post explores how past government schemes failed to address ventilation, leading to problems, and how new standards like GBIS and ECO4 ensure homes are protected.

How to ventilate a wall cavity?

Weep Vents are commonly placed directly on the flashing at the bottom of the wall, below finished floor and above finished grade.

How do I know if cavity wall insulation has been done correctly?

Borescope Inspection

A qualified professional can use a borescope to inspect the cavity walls of your property. This will help determine whether insulation has been installed and whether the insulation remains in a good condition.

How much does it cost to remove old insulation?

Expect costs of between $1 and $2 per square foot to remove insulation, with blown-in varieties near the lower end and rigid types near the top end. Keep in mind that those prices are for dry and in good condition non-asbestos insulation.

What are the disadvantages of cavity walls?

There are several potential disadvantages to cavity wall insulation. It can cause dampness and moisture problems, be expensive to install, and may not provide effective insulation for all homes. Additionally, if installed incorrectly or with the wrong materials, it may not deliver the desired thermal benefits.

Why is my house so cold even with cavity wall insulation?

This is another symptom of your cavity wall insulation's deteriorating health. Your boiler and radiators are working overtime to try and warm your house up, the heat wants to escape, and your insulation is allowing it! If your insulation can't even hold itself up, then there's no chance of it holding your heat in.

What is the best cavity wall insulation to avoid dampness?

The best cavity wall insulation to avoid dampness is likely polystyrene beads. They are superb at repelling moisture and mould growth, but unlike spray foam, do not run as large a risk of blocking air circulation in your cavity space, leading to moisture buildup.

What can go wrong with cavity wall insulation?

The top five problems with cavity wall insulation
  • It's not suitable for all homes.
  • It won't be effective if it's installed incorrectly.
  • It won't work if the property has any cracks.
  • It can sometimes damage the property.
  • It can lead to inadequate ventilation.

What is the best insulation to prevent mold?

Fiberglass insulation is constructed of tiny shards of glass that form pockets to trap air and help restrict the transfer of heat. Its naturally mold resistant in that the material itself is not a food source for mold.

Do cavity walls need to breathe?

Although insulation is to keep the warm air inside your home, it still needs to breathe. A narrow, insulated cavity is a recipe for damp, condensation and mould. No need to explain that again!

Should I remove cavity wall insulation?

There are a few reasons why you may need to remove the cavity wall insulation from a house; If the house or building was unsuitable for cavity wall insulation, if the cavity wall insulation was poorly installed, in cases of fire or flood damage, or if urea-formaldehyde was used.

Can cavity wall insulation cause mold?

Cavity walls should be sealed at the top. In cases where the cavity is left open, moisture can condense into the loft to cause dampness and mould issues.

What is the alternative to cavity wall insulation?

A similar alternative is insulating paste. Found in most hardware stores, it works similarly to wall plaster and can be applied on the inside of your property before adding wallpaper or painting. It can provide a small boost to your home's heat retention.

How many years does cavity wall insulation last?

Unless damage occurs to it, all blown-in types of cavity wall insulation should last for up to a century. For other insulation methods used during the construction process, the numbers should be similar, lasting up to a hundred years.

What is the best cavity wall insulation for old houses?

Best Cavity Wall Insulation for Old Houses: Complete 2025 Guide
  • Mineral wool is the best option for old homes, followed by polystyrene beads and polyurethane foam which are easier to retrofit.
  • Not all older homes are suitable for installing insulation as some might not have adequate infrastructure.

Is it worth topping up cavity wall insulation?

Is it worth topping up cavity wall insulation? Topping up your cavity wall insulation can be beneficial, especially if the existing insulation has settled or degraded over time. Often this can happen with certain materials like expanded foam or polystyrene beads.

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