Cavity Wall Insulation

newtonflotman

Looking to have cavity wall insulation. Hopefully free or atleast reduced price under grants. Which is more preferable? Polystyrene beads or blown fibre? The house is painted render so least amount of holes is preferable and I understand the polystyrene beads are now adhesive coated so they shouldn't fall out if you make a hole in the wall later.

Davesnave

Before you get down to discussing beads or fibres, you need to consider whether your house is in an exposed, high rainfall area.

If it is, you would be unwise to proceed with either product IMO, as there are many properties in Wales and similar wet places where dampness caused by CWI has been a nightmare for home owners.

That said, my property is quite exposed, has CWI and doesn't suffer from damp, so it's not inevitable. I just wouldn't have chosen it, because of the risk involved.

thescouselander

We've had beads installed for a few years now - so far so good. They've all stayed in and we haven't seen any damp patches.

Furts

Be very, very careful about cwi. Listen carefully to Davesnaves wise words then do a reality check. Everyone today wants an instant gratification for no effort and no expenditure. You appear no different "I want cwi, I want it now and I do not want to pay for it".

Perhaps a litle unfair, but the common sense approach is far removed from yours. This approach is my house is built of ..., my altitude is..., my degree of exposure is..., my standard of maintenance is ..., my cavity cleanliness has been inspected and is ..., my current concerns about any signs of damp are ...

When all these items have been resolved then you have to ask "am I prepared to take the risks that go with a rendered home when cwi is installed?" There are real risks here - depending on individual circumstances.

If so the next move is the product and here I would avoid blown fibres like I would avoid a plague. Then the next step is to narrow down the product and seek the BBA Approval details, or similar.

Conversely, if you are not prepared to do all this, or employ somebody who can, then you run a high risk of being yet another victim to go to the Daily Telegraph and join the crusade against cwi.

Here I will make my position crystal clear. I am not anti-cwi and I have it installed on my home - predictably the bead variant!

G_M

There have been lots of warnings that the government-sponsored move to cavity wall fill all homes is the next Endowment Mortgage/PPI scandal.

Many houses are not appropriate - it is not a suitable solution in every case, and in many cases causes consequential issues.

Not saying it cannot be a benefit - just don't assume it will be a benefit.

newtonflotman

I'm based in Norfolk, one of the driest parts of the UK. What concerned me was one of my neighbours who has a brick faced house had a company round for CWI but they instantly said they wouldn't do it on a brick faced house only a rendered one. Had blown fibre put in my previous house 15 years or so ago with no issues when I was there. This was a brand new house 2002, but just found out the whole estate has been built with no CWI due to a clause when planning permission was granted!

Furts

Planning Permission has nothing to do with cwi. Buildings Regulations does. Apologies for my confusion, but if you are saying your home is built in 2002 the following would apply.

A 2002 house will already have some form of cavity insulation because the Buildings Regulations at the time required this. These requirements were always being upgraded. If it was a Barratt home for example, this could be as simple as as an air bubble silver foil wrap around the inner leaf. This was being done circa 1997 onwards. Others might have, say 35 mm Celotex. I recall this standard having been reached by 2003.

The upshot is one cannot put in cwi because there is already insulation in the cavity. You could argue, correctly, that there is still a cavity to be filled but matters get technical and complicated here. The bottom line is I have not seen any cwi done under these circumstances.