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Is my home suitable for cavity wall insulation?

Symptoms of failed cavity wall insulation

Did you know that not all homes are suitable for cavity wall insulation? If the installation of cavity wall insulation isn’t appropriate for your home, it can cause more damage than good. Having cavity wall insulation installed into the wrong home remains one of the most common reasons as to why cavity wall insulation fails. So, are you thinking of cavity wall insulation? Do you want to know if your property is suitable? Here at First Choice Energy Ltd, we can give you all of the answers! Our aim is to ensure by the end of this article, you are fully aware of which properties should and should not have cavity wall insulation.

The ‘T’s & C’s’ of cavity wall insulation

The question remains, is your property suitable for cavity wall insulation? Here you will find not only a list of the properties that are unsuited for cavity wall insulation, but also the reasons as to why they are unsuited. The ‘Terms and Conditions’ of cavity wall insulation, if you like. It is your home at stake after all, and here, at First Choice Energy, it is our belief that homeowners should be fully aware of the reasoning behind any problems occuring in your home. So… let’s get on with it, shall we?

  • Location
  • Property detachment
  • Property structure materials
  • Cavity condition
  • Brickwork and brick pointing
  • Guttering, soffits and fascias

These are the factors that affect a property’s suitability for cavity wall insulation the most… details please!


Many of you will ask the question, does location affect your home’s ability to thrive with cavity wall insulation? The answer- it most certainly does! Here’s how-

Is your property in an exposure zone?

Meaning, any property on the west coast of the UK, for example the south and north west of England, and the whole west coastline of Wales. Any home situated in these types of locations, are unfortunately, completely inappropriate for cavity wall insulation.

The reasoning behind this is that the outer walls of your home are constantly exposed to wind driven rain. The years of this exposure on your home can damage the outer walls slightly, causing cracks in your render or brickwork. This applies even if your home is a newbuild.

The moisture will penetrate your walls, be it from weak spots in your external wall or from gaps in the window frames. The damp and moisture will then cling to whatever insulation material that is in your walls, with no opportunity to fully dry out. This will result in penetrating damp in your home, and where there’s damp, mould is sure to follow!

Does your home have a coastal facing pine-end (or gable end, in England)?

This doesn’t mean your property has to be within a certain vicinity of the coast! Even if you live pretty far from the beach, if your pine-end is facing the coast, your cavity wall insulation could cause you major damp problems!

What is a pine-end, you may ask? It’s the side of an end of terrace, semi-detached, or fully detached house with the largest wall surface area and the least amount of windows/doors. It is essentially the end of the house where the meeting of both sides of the roof is visible.

Now, this would be the area of the wall with the most cavity wall insulation. This means it is the side of your property that is most likely to cause dampness in your home… Can you see where we’re going with this? If your pine-end is facing the coast, it is constantly exposed to the wind driven rain you have read about just before. Having this face of your home insulated inevitably will cause penetrating damp in your home, perhaps it’s time you consider cavity wall insulation removal?

Property detachment

Property detachment can indeed affect your home’s suitability for cavity wall insulation! There are two short (but not exactly sweet) reasons as to why property detachment is a key factor in how suitable your home is for cavity wall insulation, these are unfortunately aimed at those of you with mid-terraced houses.

If you live in a mid-terraced home and are considering cavity wall insulation, you may want to think again..

With the only faces available for insulation being the front and the back, sometimes with not much surface area to be insulated due to the windows and doors on these faces, cavity wall insulation can be more expensive than it is actually worth! Because only two walls of your home can be insulated, it may not even save you much on your energy bills, a shame, really.

Some companies may not even attempt to insulate your home

This is because there’s an increased risk of accidentally insulating your next door neighbor’s cavity wall too, in comparison to a semi-detached, or an end of terraced house! This is something a lot of companies try their hardest to avoid as it can get them in trouble! You can’t blame them, really, can you?

Property structure materials

If you didn’t know that what frame your home has can affect your property’s suitability for cavity wall insulation, you do now! There are two main types of housing frames that shouldn’t have cavity wall insulation and they are;

Timber framed properties and steel framed properties

Both of these structures require sufficient ventilation and air circulation in the cavity wall that they support.

As for timber framed properties, cavity wall insulation can decrease the airflow in the cavity, especially if the installer is inexperienced. The lack of airflow will then increase the likelihood of condensation and moisture forming and clinging to the timber. If the timber is then unable to dry out, it can cause wood rot. This will make your home structurally unsafe to live in. The wood rot is an inevitable precursor to damp and then mould forming in your home.

The same goes if your house is a steel framed property, really. They are completely inappropriate for the installation of cavity wall insulation. Again the lack of airflow will ruin the frame of your home, not causing rot like the timber frames, but causing the steel to corrode.

Is your home an insulated timber or steel frame? If a surveyor regards your house as structurally unsafe, you could face trouble mortgaging your home, or selling it in the future!

Cavity condition

It makes sense if you think about it! The two most common issues with cavity walls that would deem your house unfit for insulation are; the amount of rubble and dirt gathered in your cavity wall, and the actual width of your cavity.

Rubble and dirt in your cavity

Rubble and dirt in your cavity can act as a bridge for damp and mould to cross over from your external wall, to your internal wall, causing penetrating damp in your home. The damp and mould will only then cling to any insulation in your cavity, causing a big old snowball effect, and worsening any small amounts of damp that were already present in your walls… that just isn’t something you want, is it?

Cavity width/span

Cavity span is an important one with regards to ventilation also. The best width for your cavity would ideally be 65-75mm. Cavities with a gap of under 50mm however, are a huge no-go for cavity wall insulation. You already know that ventilation of your cavity wall is of the utmost importance, otherwise damp and mould will inevitably occur. When your cavity is 50mm or less and insulated there will be no air circulation or venting to even attempt to dry out any damp.

Brickwork and brick pointing/striking

This may be less obvious, however, as usual, we’ve got your back! FYI, brick pointing is the addition of extra mortar between bricks either for extra weather protection in newly laid bricks or for older brickwork it is used commonly for fixing mortar joints that have been worn away from years of repeated exposure to the weather. Brick striking is basically the same thing but there is no addition to the mortar, it is just the finishing of the original mortar on newly laid bricks.

Brick pointing and striking can affect how suitable your property is for cavity wall insulation. It does, however, all depend on the type of finish your pointing/ striking has;

Flush & Weathered Finish

These are essentially the good ones! (With regards to cavity wall insulation anyhow). Flush finishing is just the mortar being completely level with the brickwork, while Weathered is a diagonal finish with the mortar beginning slightly behind the brick that’s on top and finishing on level with the face of the bottom brick.

These finishing’s allow any water touching the mortar to slide straight off the face of the wall without any water retention or penetration into the cavity wall.

Hollow Key and Recessed Key

Here, you can read about the worst for your home. Hollow Key finishing gives the mortar a concave appearance between the bricks, whilst with Recessed Key finishing, the mortar is racked out evenly between the bricks to provide a certain depth between the mortar and the face of the wall.

How are they bad, you may ask? These types of finishing’s allow any water to gather between the bricks, eventually leading to the penetration of the lingering water into the cavity wall, and if there’s cavity wall insulation in there… need we say more?

Guttering, soffit, and fascias

Now… What are these? Well, guttering is the half-pipe that runs around your roof to collect and deposit rainwater safely down a pipe to the ground floor, possibly into a drain. Fascias run under your roof tiles, providing its support, and it is also what the guttering is fixed to. Soffits will then run under your roofline.

These three come more or less as a unit, so you can imagine, if one of them is damaged, it can affect how the other works.

If a member of this unit doesn’t work, or is damaged, it can prevent the rainwater that’s running down your roof a chance to gather and penetrate any gaps it can find into your cavity wall. You’ve heard it all before, if the moisture clings to the insulation penetrating damp is an inevitability for your home.

Sooooo… if you are considering cavity wall insulation, or you have it already and you notice a member of the all-important roof drainage unit is broken, three is not a crowd in this instance, have it fixed, it is important that all three are in good condition.

Do I need planning permission for cavity wall insulation?

An often asked question by homeowners is also, is there need for planning permission to have cavity wall insulation installed? The most simple answer we can give to you is no, it is not normally required. However, if having cavity wall insulation will change the appearance of your property, if your property is in a conservation area, or if your property is listed, it is advised that you consult your local planning authority. They can then talk you through all of the regulations, and give you the best advice on how to go about having insulation installed into your cavity walls.

A quick recap...

So, the questions remain… is your home insulated and you’re unsure if it should be? Or you’re definitely sure that your home shouldn’t be insulated, and you want it removed? If you’ve answered ‘yes’ to any of these questions, why not contact us through our quick and easy survey? Here at First Choice Energy, we understand the importance of a house feeling like a home, not just a place of residence. Of course, how can you feel at home knowing that your cavity wall insulation could be ruining it? That’s why we are here to help you!

Request a call back and speak to a proffesional today