Cavity Wall Insulation Problems – Help Guide

What is Cavity wall insulation?

Cavity wall insulation (CWI) is intended to reduce the amount of heat that can be lost through otherwise empty cavity walls; the materials that then fills the space within a cavity wall (Mineral fibre, beads & polyurethane foam) trap air within the cavity, reducing convection and heat lost through space.

Does the material you use matter? yes! Click here to understand why.

When installed correctly (where the insulation fills the full space to the optimal density and where the recommend cavity width of 50mm is found either side), the potential energy savings that cavity wall insulation can deliver are unparalleled, delivering annual savings of £275 on average per year; however when fitted incorrectly there can be a whole host of problems that emerge, including damp.

About the Cavity wall insulation industry

The Insulation industry has not been without its controversies, the most recent of which has garnered a Parliamentary debate in relation to the damp and mould caused by cavity wall insulation; industry experts have even gone so far to say that this scandal could well rival that of the PPI insurance issue hence cavity claims.

Core to this has been a litany of companies that have simply installed cavity wall insulation incorrectly – be this through unknowing negligence or through sheer misrepresentation.

Currently the industry is awaiting an announcement from parliament as to what will be put into place to legislate the industry to avoid the same issue occurring again.

On the flip side of this situation however is a sometimes overlooked fact that the majority of CWI projects are undertaken successfully, with no problems emerging and only energy savings being made.

Nevertheless the outlook for the customer seeking CWI should remain one that makes the use of a reputable, professional and qualified company a must. You can read about our own credentials and experience within the market on our about us page.

Problems with cavity wall insulation are exceedingly rare, affecting only around two in every 1,000 installations. – CIGA (Cavity Insulation Guarantee Agency)

Trade bodies

CIGA (Cavity Insulation Guarantee Agency) is an independent body that issues a 25 year guarantee covering defects in materials and workmanship.

NIA (National Insulation Association) is a further impartial body where members include installers and manufacturers of insulation, with members being “committed to maintaining and raising standards within the insulation industry”.

BBA regulates the products, rigorous testing, inspection and certification services to support manufacturers and installers achieve excellence and provide reassurance throughout the industry.

The new cavity wall insulation removal industry

Because of the sheer scale of issues that we’ve outlined above, where a predicted six million properties have been affected by poor installation (The Guardian 2015), there has been an uprising in the number of professional insulation removal firms.

This side of the industry is entirely unregulated, and more than with installation it pays to choose carefully when buying this service. You can read about how we approach insulation excavations on our cavity wall insulation removal page.

Why remove Cavity wall insulation?

There may be a raft of reasons why Cavity wall insulation may need to be removed and re-installed; here we take a brief look at each, although if you’re uncertain as to the issues that you may be faced with you should contact us directly for professional help (our advice is always provided completely free from obligation and sales patter).

Damp walls

As cavity wall insulation fails, and as the moisture content within the wall rises, plaster may begin to blister and crumble. There may be a variety of situations that lead to this, including:

– CWI that has been damaged by flooding;

– Water that may have breached the cavity walls;

– The affected property may be located within a region that is known for high exposure to wind driven rain; if this is the case then standard insulation should not have been installed.

What should I do if my cavity wall insulation fails?


Mould growth emerges as a direct result of damp and, if left unchecked and un-reminded, can lead to both

serious structural issues, as well as health and safety concerns to occupants’ health (particularly the young and the infirm).


Condensation may become apparent when black mould spots begin to form on top of wallpaper and on walls (this is caused by there being warm air within the house which meets with cold wall areas). This most commonly occurs because of two situations:
Older CWI may have slipped down the cavity overtime, revealing cold spots and leading to condensation.

– In other cases CWI has simply been installed poorly, where incorrect drill patterns or blowing pressures have left spots uncovered, leading to condensation within those areas.

Jump to:

Missing cavity wall insulation

Is my home suitable for cavity wall insulation?

Wrongly installed

(Cavity wall insulation installed in timber or steel framed properties)

Timber and steel framed properties are not suitable for Cavity wall insulation; however rogue traders have been known to install cavity wall insulation regardless.

Emerging issues from these properties include damp, condensation and rot, and in all cases the insulation must be removed.

In certain instances such properties can have an alternative insulation installed, whilst in other cases another approach may be required (such as external wall insulation).

In any event it’s vital that you seek advice as soon as you’re able to if you have a timber or steel framed property can know that you’ve also had cavity wall insulation installed.

Storm & Flood damage

Storms and floods can cause insulation to become wet or damp – this effectively renders the insulation defective, meaning it must then be removed to avoid leading to damp within the building.

Penetrating damp case study

Debris in cavity

Any professional insulation installer will ensure that the cavity is completely free from debris prior to adding the insulation (this includes brick ends, sand and mortar); however, where this hasn’t been done, the insulation can be affected by debris that blocks the channels where moisture would otherwise drain from, leading to cavity wall damp.

Jump to Rubble/debris in cavity case study

Old forms of insulation (urea-formaldehyde foam)

Certain forms of insulation installed previously, such as urea-formaldehyde foam, can prove to be not only ineffective at continuing to insulate a property, In any event such an installation method has been out of routine use for so long that for properties that do have this form of insulation, they are certainly no longer benefiting from the energy savings that were once delivered.

We commonly discuss issues that cavity wall insulation can cause on our blog, providing essential advice for property owners that may need to seek further advice and guidance upon problems such as damp.

How do you detect & diagnose insulation problem

Less intrusive inspection

For some situations there are a range of inspections that can be undertaken with only minimal time and with minimal equipment; a summary of which follows (if you have any questions about these methods, or whether they would be suited to your situation, simply get in touch – we’re always on hand to answer any question that you may have).

Borescope inspection

Borescope inspections can provide for a window into your cavity wall by way of a small drilled hole, and a camera rod inserted into the wall. We use this method for a number of reasons, including confirming the presence of CWI, exploring the condition of CWI and investigating the wall within the space.

Following this service we can explain our findings, show you the images that we’ve taken and complete the process by adding appropriate mortar to fill the hole in again.

Thermal Imagery

Using thermal imagining we can gain a full understanding of how energy efficient a home (and its cavity walls) are; to do this we use sophisticated, state of the art equipment which takes pictures of the property to highlight the various temperatures. What we’re looking for here are known as ‘hot spots’ and we’ll specifically be checking to see whether the thermal images on the outside of the property can be observed in the same patter within the property. Often this serves as an initial inspection prior to undertaking a Borescope survey.

Moisture & Damp meters

Moisture and Damp meters can help provide an understanding of where there may be emerging damp issues, and how severe they may be. However, rather than measuring the moisture within an area specifically, they instead measure electrical conductance.

This fact is an important one as many home owners use DIY store brought damp meters and are confused as to why certain areas are flagging up with high readings.

In reality areas such as wallpaper are particularly ‘hygroscopic’ (which means that they effectively suck up moisture from the atmosphere); similarly timber can often be an area for confusion, as moisture and damp meters require collaborating to take a true-to-life measurement of such materials.

With so much room for confusion, and to truly get a full understanding of potential damp and moisture issues, such an inspection is best left to the professionals.

More intrusive inspection

Brick removal

There are certain circumstances where the less intrusive of methods simply won’t relay the complete picture, and in some instances we may need to remove bricks to view first-hand the state of your cavity wall insulation.

This is a last resort, as it voids any guarantee that you may have upon your insulation. Any CWI practitioner considering this method should always consult you in full before forging on ahead and beginning to remove bricks.

Read more about the steps after a thorough inspection on our cavity wall insulation removal page or loft insulation removal page.

Can cavity wall insulation be removed?

In all but the most specialist of cases the answer to this question is yes – it can be removed. That said you should always use professional cavity wall insulation removal services to undertake this project for you, rather than attempting it yourself.

How is cavity wall insulation removed?

We utilise cutting edge technology to remove cavity wall insulation that may come in a range of forms, including foam, bead and fibre. Whilst the actual process itself is simple, it does require expert know-how to understand the right approach to take and of course be able to use the equipment competently.

Removing cavity wall insulation process begins by cutting out the bricks that form the bottom part of the wall section, from the emerging gap we then use a high power, specially built industrial vacuum (which then works alongside a hose that blows air into the wall – inserted above the vacuum).

We also use other tools to help us completely clear the cavity wall (such as a whip); it’s essential that, before any new insulation is installed, that this area is absolutely free of every last piece of debris.

What’s more if we find that upon removal your old insulation is even the slightest bit damp then the wall should be left for a couple of months to dry out and truly be ready for fresh insulation.

After all of that hard work it’s then time to re-install new insulation and ensure that this time round it’s done to the proper spec to deliver those energy savings that you likely imagined when you first invested in CWI.

What are the Costs of extracting Cavity Wall Insulation?

The costs for extracting Cavity wall insulation vary from project to project, although by and large this depends upon the type of insulation that you currently have, where it is located and whether there are any access issues.

Any reputable insulation extraction company will be able to give you a rough idea of price range when supplied with the full details (and equally should provide after-visit quotes completely free from charge to confirm this).

We’re one such company – we never take any payment for merely reviewing your insulation and providing a price. You can arrange a quote by contacting us via phone on 0239 388 0032 or by email

To give you an approximate idea of pricing, let us take the example of a 3 bedroom, semi-detached home; the price range here would range between £1,800 and £2,500. This compares to a range of between £1,000 to £1,500 for a bungalow.

Learn more about the costs.

Should I upgrade by removing and replacing my cavity wall insulation?

The answer to this question wholly depends upon two things: first, whether you’re experiencing any problems due to your insulation, regardless of its age, and second, whether you could make energy savings if you were to upgrade (which you generally can where your cavity wall insulation is done before 2000)

What’s more with a wide range of government ran subsidies available upgrades can often be partially covered by a grant.

Jump to: Upgrading my insulation 

 Should I get cavity wall insulation?


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