Cavity Wall insulation downstairs only

Dave82

Hi,

We are in the process of buying a house which we love however the survey brought up one issue which is making us really nervous.

The house has an unusual cavity wall insulation installation. The upper section of the house is hung tiles and as such the firm could only insulate the ground floor.

The insulation is of the polystyrene bead type. We have had issues with badly installed cavity wall insulation in the past.

Does anyone know if this is likely to cause us future problems? How easy would it be to remove?

It's breaking our hearts but the head is saying this doesn't seem right.

Thanks

Dave

stator

Is it cross wall construction? Looks something like this:





Polystyrene bead insulation is well recommended by a lot of people. It allows moisture to drip down to the bottom of the wall instead of transferring to the inside wall, like some people claim that 'blown fibre' does.


It's certainly easier to remove than blown fibre. You just made a few holes near the bottom of the wall and a lot of it will just fall out. Getting the last balls out the bottom would be a pain. But I'm not sure why you would want to.

Dave82

stator wrote: »

Is it cross wall construction? Looks something like this:

Yes like that other than the tiles wrap round the whole upper floor.

stator wrote: »

Polystyrene bead insulation is well recommended by a lot of people. It allows moisture to drip down to the bottom of the wall instead of transferring to the inside wall, like some people claim that 'blown fibre' does.


It's certainly easier to remove than blown fibre. You just made a few holes near the bottom of the wall and a lot of it will just fall out. Getting the last balls out the bottom would be a pain. But I'm not sure why you would want to.

Only reason we would want to remove is only insulating the ground floor is not recommended practice and I was assuming there was a reason for this? Have read about issues where water pools on top of the insulation if it is not done right up to the eves I am not sure it can drain to the bottom as the beads are bonded?

stuart45

How old is the house? Some of the older ones had solid walls at the top when they were tile hung.

stator

Dave82 wrote: »

Yes like that other than the tiles wrap round the whole upper floor.

All the way around like a Cornish Unit?

dave82_2

stator wrote: »

All the way around like a Cornish Unit?

More like the first one the roof is separate

dave82_2

stuart45 wrote: »

How old is the house? Some of the older ones had solid walls at the top when they were tile hung.

1970s build

stuart45

I've worked on houses back in the 70's that were cavity on the ground floor and solid thermalite block walls on the upper floors and tile hung.
Could be this one is similar.

Dave82

Survey says it is of cavity wall construction I will ask the surveyor if it could be solid block upstairs.

They stated the reason for it only being done downstairs was that they couldn’t drill the tiles.

If it is all cavity is it likely to cause an issue? It has been installed for ~6 years would issues have shown up by now?

stuart45

It could be a cavity up top as well, although the surveyor may have just assumed that it was.
When the top half of a house is tile hung it prevents any moisture getting through to the inside so using 6 inch thermalites was cheaper and allowed a bit more space in the rooms, so it made sense to the developers not to use a cavity wall.
Problems with CWI can sometimes take a long time to surface, but it's possible that yours will be fine.
Cavity walls can be filled from the inside as well.
If you measure the walls it will tell you what they are.

UncleZen

I think this is normal not to fill the upper part with beads when the upper part is covered in tiles. They dont want the hassle of drilling though tiles that usually break.