Are cavity walls warmer than solid walls?

Author: Dr. Karelle Rath  |  Last update: Monday, May 19, 2025

Heat loss in walls Cavity walls lose less heat than solid walls and are much easier to insulate. Some parts of the country are fortunate in having relatively old homes with cavity walls. The more external walls you have, the more heat loss you will experience.

Will cavity wall insulation make my house warmer?

Cavity wall insulation can keep your home warmer in the winter and cooler in the summer. It's not just about keeping a warm house in winter, but also about preventing your home from overheating in summer.

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 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.

Is cavity wall insulation better than external wall insulation?

The advantages of external wall insulation are:

It is more effective than internal wall insulation at reducing heat loss and improving thermal performance. It can save you up to £490 per year on your energy bills.

Is my wall cavity or solid? @Domesticsurveys

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.

What is the best insulation for heat in walls?

Foam Board or Rigid Foam

They provide good thermal resistance (up to 2 times greater than most other insulating materials of the same thickness), and reduce heat conduction through structural elements, like wood and steel studs.

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.

How often should cavity wall insulation be replaced?

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.

Is it worth replacing old cavity wall insulation?

A well-insulated home is seen as a more valuable investment due to its energy efficiency and reduced maintenance needs. By removing a failing wall insulation (and replacing it with a new one), you're preserving the integrity and value of your home.

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.

Are solid walls better than cavity walls?

Cavity walls lose less heat than solid walls and are much easier to insulate. Some parts of the country are fortunate in having relatively old homes with cavity walls. The more external walls you have, the more heat loss you will experience.

What is the disadvantage of cavity?

Having a cavity is no laughing matter. Besides the toothache, it can also lead to more permanent damage and costs. It's important to see your dentist and have that cavity filled.

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.

How do I make my internal walls warmer?

Internal wall insulation is done by fitting rigid insulation boards to the wall, or by building a stud wall filled in with insulation material such as mineral wool fibre. Internal insulation: Is generally cheaper to install than external wall insulation.

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.

Why is cavity wall insulation being removed?

Poorly installed insulation is now causing damp and or cold spots internally. The insulation has become defective or is unsuitable. The insulation has got wet due to the property being poorly maintained. The insulation has suffered water damage due to a flood or fire.

How can I tell if my cavity wall insulation is working?

The signs of cavity wall insulation failure could be as simple as noticing patches of dampness on external walls or could be recognising that the installation isn't delivering the energy-saving benefits it should.

Do 1970s houses have cavity walls?

Houses built in the 1970s generally have cavity walls, but not all were constructed with insulation. Checking the EPC of a 1970s home can confirm if insulation was installed.

How to check if walls are insulated?

Check Your Wall Insulation Level

Remove the outlet cover and shine a flashlight into the crack around the outlet box. You should be able to see if there is insulation in the wall and possibly how thick it is. Pull out a small amount of insulation if needed to help determine the type of insulation.

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.

What is the best insulation for 100 degree weather?

Fiberglass Insulation

Fiberglass is the most common type of insulation used for residences because it is by far the best, particularly for hot climates. Here's why: Fire-retardant – Fiberglass insulation is fire-retardant, making it an ideal choice for homes in dry climates and areas prone to fire.

What is the thinnest insulation with the highest R-value?

Thermablok® Aerogel is a revolutionary advancement in thermal technology offering the thinnest insulation available to prevent thermal and cold bridging. Classed as a Super Insulation, Aerogel has the highest insulation value of any known material with the lowest thermal conductivity value of any solid (0.015W/mK).

What is the best insulation to keep cold out?

Fibreglass insulation is the most effective for frigid climates; it can be applied to walls, lofts, and other areas where heat may escape. Adding insulation can reduce energy costs and maintain a comfortable residence throughout the winter.

Previous article
Can you use baking soda on bamboo?
Next article
How do I reset a deep freezer?