Does Cavity Wall Insulation Cause Damp? A UK Guide

Cavity walls are a popular build throughout the UK, making up around 71% of all properties throughout the nation. However, nearly 6.1 million cavity wall properties still lack adequate insulation for walls, leading to sky-high energy bills, damp homes, and huge carbon footprints.

Cavity wall insulation is a quick, non-invasive, and highly effective method of insulating your walls, but like any insulation job, there are several proactive measures you can take to avoid problems such as dampness and mould growth. Yet the real question is, can cavity wall insulation cause damp?

This complete GreenMatch UK guide will provide everything you need to make the right decision on your cavity wall insulation, including potential problems, solutions, and insider tips on how to get the best out of your cavity wall insulation.

Ready to get your cavity walls insulated? Let GreenMatch UK be your one-stop solution to finding the most professional installers at the best bargains. Instead of spending endless hours on the web, just spend 30 seconds filling out our simple online form, and we’ll deliver you up to 3 free home-tailored quotes. No charges, no obligations. Click below to begin!

Cavity wall insulation does not cause dampness itself, but damaged cavity walls or a poor installation job certainly can. In most cases, cavity walls with cracks and gaps in the outer brickwork can invite moisture to build up in the cavity space. 

Other factors such as loose insulation, poor ventilation, or even wind-driven rain can all contribute to moisture buildup in the cavity space. 

Cavity wall insulation causing damp only happens if it is poorly installed. As cavity insulation bridges the gap between the outer and inner walls of your home, it makes it very easy for moisture to travel from the outer wall to the inner wall if compromised.

Luckily, a professional installation and some proactive steps can help avoid this problem.

Whilst cavity wall insulation itself won’t cause dampness issues, even the best cavity wall insulation can benefit from knowing how dampness issues can arise. The key problems are:

Having a good understanding of the potential pitfalls associated with cavity wall insulation and damp will help you proactively plan and avoid any issues from arising. It can also give you a better idea of whether cavity wall insulation is suitable for your property.

The most common cause of cavity wall insulation damp for homes is the poor condition of cavity walls. More common in older properties, cavity walls with cracks, gaps, and loose bricks on the outer wall are improperly sealed, and at risk of collecting moisture. 

When you install cavity wall insulation, it bridges the gap between the outer and inner walls. If the outer wall is porous, moisture can travel through the insulation material and collect on the inner wall, leading to dampness in your home.

That’s why it's important to conduct a wall assessment to ensure your cavity walls are in the necessary conditions to house insulation. 

Similar to the case of poor-condition cavity walls, there may be outstanding issues that, without repairing, are also causing dampness even before you get cavity insulation. 

One common issue can be a lack of proper ventilation. While it’s true that the cavity space should be sealed shut, an installer needs to account for draining rainwater in case it gets into the cavity space. For this, some degree of ventilation needs to be considered.

Another common issue can be an unclean cavity. If there is outdated insulation or debris left in the cavity space, this can act as a bridge that transfers moisture from the outer wall to the inner wall. Before you add any new insulation, it’s important to make sure your cavity space is clean.

Poor workmanship and a shabby installation job can be the difference between a warm cosy home, and a financial trainwreck. 

Unprofessional installers may not take into account existing wall damage, repairs, or ventilation when installing the cavity wall insulation. To avoid this, work with a professional installer.

A helpful tip, cavity wall insulation cannot be done DIY. It requires a professional with training and access to industry-standard equipment. To ensure you get the best quality of work, aim to hire a CIGA-certified installer. The Cavity Insulation Guarantee Agency (CIGA) even provides up to 25-year guarantees on cavity wall insulation jobs. 

The geographic location of your home and its exposure to wind and rain can play a huge role in whether cavity wall insulation is the right choice for you. 

Simply put, when the cavity space is filled with insulation, it bridges the gap between the outer and inner walls. Unsheltered homes frequently exposed to wind-driven rain will have soaked outer walls. This moisture can travel through the insulation to your inner walls, causing a damp home environment.

A study backed by the UK Government, carried out by UCL and BRE looked into areas of the UK that have high exposure to wind-driven rain. The study splits the UK into 4 zones of rainfall and considers areas of high exposure to be zone 3 or above. 

Therefore, homes classified as zone 3 or 4 are not recommended to get cavity wall insulation, unless your home is in a properly sheltered area. Cavity wall insulation alternative approaches, like internal wall insulation or external wall insulation, may be more suitable in this case.

Before a problem gets out of hand, there will be telltale signs of moisture and dampness in your cavity walls. By noticing these issues in their earlier stages, you win the chance to avoid hefty repair bills down the line. Here are some things to look out for:

Are you noticing any of these telltale signs of failed cavity wall insulation? Don’t know how to check cavity wall insulation? It’s best to get your cavity wall insulation professionally assessed to determine whether it’s been compromised or not. Dealing with these problems proactively can help save you hefty repair bills in the long term. 

If your cavity walls are suffering from dampness issues, it’s not the end of the world! Thankfully there are several ways these problems can be solved with long-term benefits. 

It’s good to know that cavity wall insulation cannot be handled DIY and that a professional is needed. Choosing the right installer can be the difference between decades of comfort, or endless hefty repair bills. 

Knowing how to identify and solve cavity wall dampness issues proactively will help make sure your home environment and insulation stay healthy and functional. Taking into account the most common cavity wall insulation problems, here are some tips on how to solve them:

While it may sound easy, finding a professional installer at an affordable price can be quite a challenge. Most of us don’t have endless hours to spend scouring the web and scheduling phone calls with potential contractors, but GreenMatch UK can help you out! 

Through our nationwide network of trusted professionals, we can deliver you up to 3 free home-tailored quotes at competitive prices. Our services are completely free and without obligations. Simply spend 30 seconds filling out our form and let the bargains come to you. Click below to begin!