A blog post

The Hidden Dangers of Cavity Wall Insulation – ‘Not Fit for Purpose’?

Posted on the 17 April, 2014 at 3:40 pm Written by in Cavity Walls, Damp

Following the horrendous weather conditions of the past months, apart from those unfortunate people who have had their homes flooded, the significant rainfall has again highlighted the problems associated with Cavity Wall Insulation and its ability to transmit moisture between the outer and inner walls of traditional cavity brick built houses. Cavities are formed for the sole purpose of keeping the weather out, if not they would be constructed with a solid wall, as they would be a lot easier to construct.

The traditional cavity wall dates back to the early 1900’s and is commonly found in the coastal areas around Britain being constructed to reduce the risk of rain penetration. In the

Cavity wall insulation

Cavity wall insulation

1920’s, local building by-laws encouraged the construction of the cavity wall and by the 1940’s it had become the Industry Standard. The typical cavity wall is two leaves of brickwork (or block), forming an approximate 60mm cavity and tied together with a network of metal wall ties.

So why do people install Cavity Wall Insulation? Well, to keep warm and save energy seems to be the normal response.

But does it really keep you warm? Is a wet wall incorporating wet insulation material a good thermal insulator?

Answer NO, a ‘wet wall = a cold wall’, so how does that keep you warm and save energy?

In the UK we are currently experiencing some of the highest energy costs ever known and our leaders i.e. our government (past and present) continue to encourage property owners to insulate their houses to SAVE ENERGY and to SAVE the PLANET.

Even as long back as the 1970’s concerns were starting to be expressed over Energy Conservation so the debate is not that new, although may now be a bit of a reality considering most of our energy companies have been sold off and most of our energy comes from Europe and beyond.

Government lead schemes such as the Green Deal and many grant aided, encourage us to insulate our lofts and cavity walls and only this week there was an feature in a local magazine which read………

”Cavity wall insulation can save you on average £190.00 per year on your bills”, ………..

Tell that to the guy whose house we recently surveyed and identified the insulation as being responsible for significant dampness and has just spent £1,600.00 plus vat, having the wet insulation removed from his gable wall due to extensive dampness affecting the porous masonry on the weather prevailing elevation of his 1970’s detached house.

The mineral wool insulation which was reported to have been installed over 25 years ago by the previous occupants was saturated at the base of the wall and in areas to in excess of 2.mtrs even effecting the wall lights, causing extensive damage to the internal decorations, plasterwork, skirting joinery and also the parquet flooring which was starting to delaminate. More worrying however, was the extent of corrosion to the electrical back boxes and brass cover plates.

Here at Premier we have investigated a significant number of cavity properties over many years, all of which had one thing in common, that various walls (particularly those of the weather prevailing elevations) were affected by significant levels of internal dampness caused by the long term bridging of moisture (rain water) through the insulation materials.

Regular readers of this site will be fully aware of the various posts on the issues of damp caused by cavity insulation materials, and this whole process can take many years to develop and obviously doesn’t affect all properties, but certainly over the past few months Premier have seen a threefold increase in telephone enquiries relating to this particular problem, given the recent weather conditions we have experienced. That said, it has to be assumed that this problem will certainly get worst in the coming years given the predicted changes in our weather patterns.

Our personal opinion is that cavity wall insulation materials (of whatever type) retrospectively installed into an existing cavity wall doesn’t really make a great deal of difference to the overall Thermal insulation value of the wall, given that most of the cases we’ve investigated over the years many were clearly not installed to the required standards, with large areas void of any insulation material and with some systems (poly beads) areas of obvious settlement.

Wet insulation materials provide no Thermal benefit!  However despite the continuing number of horror stories on the Internet, the government continue to bang the drum on the benefits of Cavity Wall Insulation, which in our opinion is NOT FIT FOR PURPOSE.

We wonder if you can get a Government grant to remove insulation, we think not!

1970s block constructed house

1970s block constructed house

Extensive dampness to wall in sitting room

Extensive dampness to wall in sitting room

Decorative damage can just be seen below the light fitting

Decorative damage can just be seen below the light fitting

Light fitting corroding and rust marks running from underside

Light fitting corroding and rust marks running from underside

Damp bridged through to fireplace stonework

Damp bridged through to fireplace stonework

Parquet floor in front of fireplace delaminating

Parquet floor in front of fireplace delaminating

Carefully cutting out the stone blocks

Carefully cutting out the stone blocks

Extent of block work removal  to remove insulation

Extent of block work removal to remove insulation

Back of blockwork clearly damp

Back of blockwork clearly damp

Insulation wet when compressed

Insulation wet when compressed

Is it supposed to stick together like this?

Is it supposed to stick together like this?

Big squeeze equals puddle of water

Big squeeze equals puddle of water

 

some comments

There are currently 5 of them
  1. Derek 16 May 2014 at 11:00 am permalink

    This is a fantastically informative blog. One thing I hate is people who are forever saying cavity wall insulation will save you money.. Not in the long run it won’t!

  2. Liam 16 May 2014 at 11:19 am permalink

    Do you actually offer cavity wall insulation extracting services?

  3. Premier Heritage 27 June 2014 at 10:40 am permalink

    Hi – we are surveyors so don’t offer extraction services I’m afraid.

  4. Helen 3 March 2015 at 4:44 pm permalink

    We have an ‘undercroft’ to our house and quite a bit of cold air comes up through the floor. Is it worth insulating under the house and or is it possible to do so? At the moment we have no damp issues (cavity wall, timber frame with block and render skin – Scottish islands climate!)but I don’t want to compromise this to save a few quid on bills.

  5. Simon C 22 May 2017 at 1:37 pm permalink

    Can I ask, do you think beeding cavity insultation is a better option/might even of avoiding the issue detailed above


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