21st Nov 2022 -

Cavity wall insulation can bring excellent levels of thermal insulation to your home for an affordable price. But problems such as condensation and mould can arise, either when it is installed in unsuitable properties or installed to a low quality. These problems have grown so extreme that a Welsh MP recently called for an independent government inquiry to determine the scale of the problem.

In this guide, we will lay out the circumstances that would make your home unsuitable for cavity wall insulation, and the telltale signs of cavity wall insulation problems within your home. This will help you to make an informed decision about cavity wall insulation and to spot problems before they become serious. When installed properly in a suitable house, cavity wall insulation increases the energy efficiency of your home, saving you money and keeping you warm.

Is Your Home Suitable for Cavity Wall Insulation?

The vast majority of homes constructed after the 1920s will feature cavity walls, but not all homes with cavity walls are suitable for insulation. In recent years there have been a series of news stories about the problems caused by retrofit cavity wall insulation being installed in old houses. Regardless of where you live in the UK, it is worth getting an independent survey of your walls before insulation is installed.

The main reason your home would be unsuitable for cavity wall insulation would be if it is located in an area with a high level of wind-driven rain. This covers a large part of the west of England and Scotland, including almost all of Wales. Severe levels of driving rain can cause damage to properties with cavity wall insulation, with penetrating damp passing through to your internal walls. You should check if your property is in an area of high wind drive before pursuing cavity wall insulation, as many properties in these areas have faced severe difficulties with damp problems as a result of fitting it.

Just because insulation providers are offering fittings in your area, that does not mean your home will be suitable. Getting an independent survey of your walls can help you ensure you do not insulate an unsuitable property. Your survey should check the condition of your walls, the condition of wall ties within your cavities, and that your cavities are free of debris.

Another issue in a house that could prohibit the safe installation of cavity wall insulation is damage to your outer walls or uneven walls. Hiring a surveyor to examine your outer walls will make you aware if there are any serious structural issues to your property. Houses with damaged brickwork or insufficient mortar can be penetrated by rain, causing damp spots, condensation problems, and mould within your house.

What Are the Problems With Cavity Wall Insulation?

Cavity wall insulation problems arise for two main reasons, either that your home was unsuitable for cavity wall insulation, or that your cavity wall insulation was poorly fitted. In a home that is unsuitable heavy wind-driven rain can penetrate through your outer walls, causing moisture penetration and condensation problems. The moisture passes through your cavity wall insulation, especially if your wall is insulated with loose-blown or mineral fibre insulation. Damp cavity wall insulation will lose much of its insulating properties and can penetrate your internal walls, causing dampness, stains, peeling wallpaper, and even mould. This can even lead to black mould, which can cause serious health problems.

If your external walls are cracked or damaged, this can also lead to water penetration, putting your home at the same risk. The external brickwork of your house can also crack and degrade due to freezing when damp. Expanded Polystyrene (EPS) beads are a form of insulating material that can last better with dampness, with a higher chance of drying out. However, if your home is either in an area of high wind-driven rain or has damaged exterior walls, you shouldn’t take any risks, even if different types of insulation may offer better results.

Poorly installed retrofitted cavity wall insulation can also cause condensation problems. Insufficient or uneven cavity wall insulation can cause cold bridging within your walls. Cold bridging is a weak spot in insulation continuity, which attracts air moisture and can lead to issues like black mould, which can cause health problems. It can also cause penetrating damp, unpleasant odours and difficulty heating your house.

How to Fix Cavity Wall Insulation Problems in Your Home

If you have had your cavity walls insulated and are experiencing any of the above problems, there are a series of things you can do. Many reputable installers will offer a guarantee of quality covered by the Cavity Insulation Guarantee Agency (CIGA). If your cavity wall insulation is covered by a guarantee, the installers are liable for any damage caused to your property and will be contractually obligated to sort it out. If a surveyor you hired incorrectly recommended your house for cavity wall insulation, they may also be liable. While guarantees from groups like CIGA should cover any repair work needed, in some cases you may be required to take legal action if you have been mis-sold cavity wall insulation.

If your installer did not offer a guarantee, you have two options, topping up your cavity wall insulation or having it removed. If your walls are solid and your installation was insufficient, it will be a cheaper option to top up your cavity wall insulation. To have cavity wall insulation removed will require a specialist process, which involves removing bricks from the wall, vacuuming out insulation with a cavity wall extraction system, and thoroughly checking the cavity to ensure it is free of debris. Cavity wall insulation removal is likely to be an expensive process, costing around £2000 for a whole house.

How to Ensure You Avoid Cavity Wall Insulation Problems

While cavity wall insulation can be a great and affordable way to provide insulation to your house, it can cause major issues in older houses when installed incorrectly, or when installed in unsuitable houses. These issues can damage your walls, threaten your health, and cost thousands of pounds to fix.

Before embarking on a cavity wall insulation project, you must engage a surveyor to thoroughly check your property, referencing the levels of wind-driven rain in your area. If you have received the go-ahead from them, then you should choose a certified installer, who offers a guarantee for their work. These two steps will help ensure a quality, long-lasting, and suitable layer of insulation around your home. And should any cavity wall insulation problems arise, you will have a clear course of action to have them rectified. It is always a good idea to check if you are eligible for a grant from the government for cavity wall insulation, in which case you will receive a free survey of your walls before work starts, allowing you to avoid mistakes.

High-Quality Insulation Products in Stock

Building Materials Nationwide offers a wide array of insulation products for sale. If your home is unsuitable for having its cavities filled with insulation, internal wall insulation can be a great energy-saving alternative. Whether attaching insulation boards to your wall or building an internal stud wall, we offer excellent insulation boardsrolls and slabs.

We also have a range of insulated plasterboards. Our product range can be delivered across the UK. If you found this guide helpful, we have a range of building guides available through our website, such as our guide to making your home more energy efficient. For trade customers, sign up for a beneficial trade account which includes competitive trade pricing, your own designated account manager and a simple procurement process. You can also send us your questions using the form below.

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