Cavity wall insulation on ground floor only??

itm2

We've just had someone round to quote for CWI for our 3-storey townhouse. The basic quote was £1,900, but due to a very narrow side alley scaffolding would be necessary to access everything other than the ground floor. This would add £1,000-1,500 to the price.

Our main priorities are 4 rooms:

- Master bedroom on the top floor: The surveyor said that the main external wall of this room wasn't a cavity wall, so only the shorter external wall could be insulated

- Kitchen on the 1st floor: This is fully fitted, so the fitted furniture provides a degree of insulation. It has a large window and a semi-glazed door - we are planning to buy thermal blinds to mitigate heat loss from these

- Study on ground floor

- Lounge on ground floor: this is a single-storey extension, with 3 exterior walls.

Since the largest exterior wall of the bedroom can't be fully insulated anyway, and the kitchen has fitted furniture providing some insulation, it would seem sensible to focus on the two ground floor rooms - particularly as this is where we spend the vast majority of our time.

My question is: would it be feasible or sensible to insulate the ground floor only - hence massively reducing the cost, and targeting the spending at the most important areas?

stuart45

If moisture penetrates the outer skin and runs down it's got a ledge for it reach the inner skin.

itm2

stuart45 said:

If moisture penetrates the outer skin and runs down it's got a ledge for it reach the inner skin.

The quote was for EPS Beads - I understand these allow moisture to trickle down to ground level if correctly installed?

stuart45

You're probably best talking to the CWI company about it. Moisture can run down and out slightly off any mortar snots into the centre of the cavity and drop down and bounce, so it's up to the firm of they think it's OK.

itm2

stuart45 said:

You're probably best talking to the CWI company about it. Moisture can run down and out slightly off any mortar snots into the centre of the cavity and drop down and bounce, so it's up to the firm of they think it's OK.

Thanks yes I did ask them. Still waiting for a reply

FreeBear

itm2 said: My question is: would it be feasible or sensible to insulate the ground floor only - hence massively reducing the cost, and targeting the spending at the most important areas?

Feasible to insulate the ground floor only - Yes. I had just the lower half of my property done quite a while back (under a government scheme).

Sensible - Debatable. It will probably save a lot less energy than you have been told. The Energy Saving Trust claims that I would save £280 per year. Actual saving for me is probably zero. Noticed absolutely no improvement in comfort levels or changes to the energy bills. Fitting low-e windows and plugging the cold draughts has made a huge difference. Increasing the loft insulation above the recommended 270-300mm thickness has also helped. Whilst new windows was a major expense, extra loft insulation, a nominal cost (fitted myself).

stuart45

FreeBear said:

itm2 said: My question is: would it be feasible or sensible to insulate the ground floor only - hence massively reducing the cost, and targeting the spending at the most important areas?

Feasible to insulate the ground floor only - Yes. I had just the lower half of my property done quite a while back (under a government scheme).

Isn't your house solid wall construction on the upper floor and cavity ground floor? I think this one is cavity above.

itm2

The installer has told me that they can't insulate ground floor only; they have to insulate the levels above because of the potential for knock-on condensation issues.
As our lounge is a single-storey extension, with nothing above it, I've asked if it would be feasible for that to be done in isolation. It's obviously one of the most important rooms. If it can be done for a few hundred it might be worth a punt.
I suspect they'll say no, though...

stuart45

If there's nothing above there shouldn't be a problem. You can build an extension with full fill cavity insulation on to a house with empty cavities.

MikeJXE

Personally rather than not do it or pay 1000-1500 for scaffold I would consider filling the cavity from the inside if at all possible, depending on the cost to make good 

FreeBear

stuart45 said:

FreeBear said:

itm2 said: My question is: would it be feasible or sensible to insulate the ground floor only - hence massively reducing the cost, and targeting the spending at the most important areas?

Feasible to insulate the ground floor only - Yes. I had just the lower half of my property done quite a while back (under a government scheme).

Isn't your house solid wall construction on the upper floor and cavity ground floor? I think this one is cavity above.

You have a very good memory