Is cavity wall insulation worth having?

Lee_Howden

We've been toying with the idea of having Cavity Wall Insulation done. Some people recommend having it done from the point of viwe of having a warm house.

However, somebody who works with me has spoke to a friend of his who is a builder and he wouldn't receommend having it done as a house needs to be able to breathe.

Can anyone on here give any advice? Also, if people have had it done, have there been any problems after having it done? I've noticed on another thread that someone had got problems with condensation in their loft space?

andrew-b

Yes get it done..the bottom line is it will save you money in heating costs. Problems are very few and far between with the insulation material used these days. So long as you get the 25-year independent CIGA guarantee i wouldn't worry and would just get it done. The millions of people who have already had cavity wall insulation installed without any problems can't all be wrong surely?

I can't really see how cavity-wall insulation could cause condensation in the loft - more likely loft insulation was installed tight to the eaves (should be a gap for ventilation) at the same time causing condensation. For us having cavity wall insulation installed actually reduced condensation from forming on walls inside the house as it made the inner leaf of the wall closer to the room temperature.

Andy

brig001

The benefits will depend on the construction of the house and the quality of build. We had draughts blowing under our upstairs floorboards from the cavity and it has certainly reduced those. If you have a cold upstairs room, you would definitely benefit. I believe that timber frame houses shouldn't be done, so I would check that first.

B&Q will do the job for £200, so to me it was a no-brainer.

Brian.

27col

I find it hard to believe that there are still dinosaurs out there who think that cavity wall insulation is not a good thing. As andrew-b says it's the bottom line that counts. Anyone who thinks that cavity insulation is not necessary, must have more money than sense. Millions of householders know and appreciate the advantages and the reduction in heating costs. I had mine done when I built the house 30 years ago. This was the light weight expanding foam, and we have never had a problem.. What causes roof condensation is generally lack of air cross flow in the loft and this is caused by badly positioned loft insulation. There are many posts on the subject and a wealth of information to be found on the net. It is possible that damp patches on exposed walls could develop, but it is probably true to say that they would be likely to be due, to wall ties which were not kept clean during the building process, and have deposits of mortar on them. This problem can be dealt with if it occurs. If there are dirty wall ties, they likely to cause a damp patch whether or not the wall is cavity filled.

natjay_2

Well we live in a house that had cavity wall insulation installed prior to us buying the house, now the back of our house catches all the weather and over the years some of the bricks have become porous and the pointing is not quite what it used to be and during the very wet summer and the continuing bad weather we are starting to get water ingress at the back of the house

Now over the years some of the bricks have suffered frost damage and the faces are no longer waterproof now the quickest way to cure our problems is to have the house rendered which is going to cost us a lot more money than the cavity wall insulation have saved us over the years

Now I am not saying that the cavity wall insulation caused our problem but it has allowed water to bridge the cavity and damage the plaster on the interior walls

moonrakerz

natjay wrote: »

Well we live in a house that had cavity wall insulation installed prior to us buying the house, now the back of our house catches all the weather and over the years some of the bricks have become porous and the pointing is not quite what it used to be and during the very wet summer and the continuing bad weather we are starting to get water ingress at the back of the house

Now over the years some of the bricks have suffered frost damage and the faces are no longer waterproof now the quickest way to cure our problems is to have the house rendered which is going to cost us a lot more money than the cavity wall insulation have saved us over the years

Now I am not saying that the cavity wall insulation caused our problem but it has allowed water to bridge the cavity and damage the plaster on the interior walls

I would say that poor upkeep of the fabric of your house is more likely to be the cause of your problems than the insulation - if the pointing wasn't bad the water wouldn't get in to start with.
How do you know it is the insulation bridging the cavity ? mortar on the brick ties has been causing this problem since long before cavity insulation was even thought of.

andrew-b

...i'd agree with Moonrakerz about your problem. Cavity wall insulation is designed to be water repellant and not to allow water to bridge it. For example see the features of Rockwool cavity wall insulation (which is what we opted for after i researched the different sorts available). Also note the "vapour permeable" part which makes Lee's builder's argument invalid. Some good info on that site such as the FAQs.

Incidentally to search/apply for a grant towards cavity wall insulation goto Energy Saving Trust

Andy

natjay_2

The cavity wall insulation that we have in our walls was installed between ten and fifteen years ago and was not done by us so we have no idea what type of insulation was used or how well it was installed

If I had a choice I would not install it, the cavity was left empty for a reason

As I said in my other post I know it is not the cavity wall insulation that caused our problem but I do feel that it has compounded it

neilofnorton

Moved into a new bungalow in 1971-immediately had ICI to do the foam insulation. They were very thorough-weighed their "foam mix" until they achieved the right mix. If wrong the foam can disappear over a period.
The difference in the heat retention within the walls was noticed immediately.

10 years later built an extension on the side-when they took down the bricks on either side of the wall, the cavity foam was still in superb condition-the extension was also done.

37 years later there has been no obvious signs of any problem with the brickwork-no dampness whatsoever.

I thoroughly recommend my process-foam.
Possibly the products have improved since I had mine done

prettypennies

We had our cavity wall insulation done about 6 or 7 years ago and it did make a reall difference to the house's ability to retain heat. I have noticed more condensation in the loft space, particularly in winter. However I think that is down to the loft insulation which was replaced at the same time. The house should still be able to 'breathe' as the airbricks are retained

latecomer

Make sure your replacement insulation doesn't go right to the eaves as that will allow the roof space to breath and help cut down on the condensation.