How to tell if a cavity wall is insulated?

Author: Violette Gorczany  |  Last update: Monday, September 29, 2025

How do You Know if you have Cavity Wall Insulation
  1. Look at the Age of Your House. ...
  2. Examine the Brickwork. ...
  3. Check for Drill Holes. ...
  4. Contact a Professional. ...
  5. Use a Thermal Imaging Camera. ...
  6. Type of Insulation Material. ...
  7. Condition of Insulation.

How can I tell if my wall is insulated?

If you feel you're hitting something soft and pillowy, you've got insulation. If you immediately hit something hard, you're probably bumping into a wall stud -- try the other side, top, or bottom. If you can wiggle the skewer around and touch it to the inside face of the exterior wall -- bad news, no insulation.

How to check if cavity wall insulation is wet without?

How to check if cavity wall insulation is wet?
  1. Damp patches on walls – If you notice damp patches on your internal walls, this could be a sign that your cavity wall insulation is wet. ...
  2. Musty odours – If you notice a musty odour in your home, this could be a sign that your insulation is wet.

How can I prove I have cavity wall insulation?

Look at your property's EPC (Energy Performance Certificate)

It will usually state if they are cavity or solid in structure. If you can't find your EPC at home, you can use your postcode to look it up on the Government's EPC Register.

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.

How to check for cavity wall insulation

How do I know if my cavity wall is insulated?

The simplest way is to check your brickwork for drill holes. If you notice small, evenly spaced holes that have been filled in, this is a sign that cavity wall insulation is installed.

Should insulated walls feel cold?

If your walls feel cold when you touch them, then it is likely that your home is not well insulated. Fortunately, you can easily make your walls warmer by installing extra insulation and completing other home energy upgrades. This will reduce heat loss, lower carbon emissions, and save you money on utility bills.

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.

How do you insulate an existing wall cavity?

You can blow spray foam or cellulose into the walls from outside. Just cut a 1 inch to 2-inch hole between the studs at the top of the wall and then spray the insulation into the hole using a hose. Replace the cutouts, fill using wood filler and then sand smooth and paint to restore your siding.

Should a cavity wall be filled with insulation?

Many people, including some building professionals, believe that wall cavities should never be filled and that insulating cavity walls will inevitably lead to damp bridging. But this is simply not true. To date, around 4m UK homes have had cavity wall insulation retrofitted.

Is it OK for cavity wall insulation to get wet?

If your insulation has become wet, remove it as soon as possible and replace it with new insulation. Wet insulation can lose its effectiveness and can pose health risks.

How do you check for moisture behind walls?

How to detect moisture behind walls? Moisture within and behind walls can be detected with a pinless moisture meter. A non-destructive moisture meter can accurately locate and measure elevated moisture levels without the need to break the wall's surface material.

Will pink insulation dry out?

Glassfiber insulation is made from strands of glass fiber and temporarily loses its thermal resistance when it gets wet. However, if it can dry out and has not become compacted, it will retain its insulating properties. Wet insulation in a closed wall cavity will usually not rapidly dry out.

What happens if your walls are not insulated?

Uninsulated external walls can also cause structural damage to your home over time. When water penetrates the walls, it can freeze and expand, causing cracks and weakening the structure of the wall. This can lead to more significant problems, such as collapsing walls, which can be dangerous.

How much heat is lost through insulated walls?

About 35% of the heat will escape through the walls and through gaps, in and around windows and doors, and about 10% of heat will disappear through the floor. Taking action to make sure your home is energy efficient has many benefits. For your pocket, for your comfort and for the environment.

How can I tell if I already have cavity wall insulation?

Look for Signs of Installation

If you notice small, evenly placed holes on the outside brick wall, it could indicate that insulation has been installed. The best places to look are under and by the side of windows as these are commonly drilled sections when insulating a cavity wall.

How do I know if my walls are insulated?

You can check insulation in walls by removing an outlet cover or light switch to take a quick peek inside the wall to determine if there is any existing insulation in there. Another option is to drill a hole somewhere inconspicuous, like in the closet or under the baseboard, to take a look.

What is the life expectancy of cavity wall insulation?

Here are some common types of cavity wall insulation and their approximate lifespan: Mineral Wool Insulation: 25 to 30 years. Foam Insulation: 20 to 25 years. Bead Insulation: 30 to 40 years.

What is the downside to cavity wall insulation?

This means that there will be a moisture build up in your walls. The moisture will transfer to your cavity insulation, and damp and mould will begin to develop inside your walls. This really does become a hindrance for you when the mould starts growing inside your home, and damages your things.

Can I top up cavity wall insulation?

Can Cavity Wall Insulation be Topped Up? As long as the insulation within your cavity wall isn't damaged, then it can be topped up. This can be a difficult process, and unless there has been severe damage it is unlikely to offer enough of a benefit to your levels of heat loss to justify the price.

How to tell if a house is poorly insulated?

Missing insulation allows either heat or cold to infiltrate, which shows as hot or cold spots on your walls or ceiling when viewed by a thermal camera. You can easily detect areas of missing insulation by walking around your house with a thermal imager and looking for temperature differences.

Why does my house feel cold at 73?

If you're cold even though your thermostat indicates you shouldn't be, your furnace likely isn't the problem. In most cases, it's working just fine. It's your home that needs attention. Lack of insulation, severe air leakage, and/or unbalanced ductwork are frequently to blame.

Can walls be too insulated?

In fact, adding too much insulation to your walls can lead to problems such as poor ventilation, mould growth, and condensation. This is because thicker insulation can block airflow and trap moisture, leading to indoor air quality issues and even structural damage.

Previous article
What causes cast iron to break?
Next article
Can you build a foundation with quikrete?