Cavity downstairs and solid wall upstairs?

[Mick6]

The walls of our 1930's house appear to be thinner upstairs than downstairs, most obvious on the landing where there's a shelf / second window sill:

neighbour told me that, when she had cavity wall insulation recently, the installers were only able to do downstairs. She wasn't sure whether this was because upstairs was solid or a thinner cavity.

Has anyone come across this type of construction before? Is it more likely that it's solid or just a thinner cavity? I'd have thought that, if a cavity existed, it could be filled with the kind of blown insulation that's used today.

Thanks.

[Phil L]

As a CWI installer I came across this from time to time, and while not very common, it's not a rarity neither - I think builders went through a short spell of doing this as you say, around the 30's, and yes, the shelf on the stairs is a feature of all of them.

With regards to having them insulated, they will only insulate the lower part because while there may be a small cavity upstairs, an inch at most, this isn't possible to insulate by injection, and even if it were, it would be useless as mineral wool only works over 40mm in thickness, and you could never get the correct density given that the inch cavity would be completely solid in parts where debris has filled it

[Adrian Chapman]

if very similar construction. The ground floor walls comprise a conventional nine inch solid wall with an inner single brick thick inner skin, while the upper floor is just a nine inch wall, externally rendered and pebble dashed.

Adrian

[Mick6]

Thanks for the reply, Phil.

Do you happen to know roughly what the going rate for a 3-bed semi would be up north -- and if you only have the ground floor done, is it half the price or doesn't it work like that?

I'm assuming we'll have to pay as most of the grants on

are linked to various state benefits.

[Phil L]

Approx 5 quid a metre, measure from your internal floor to your 'shelf'. write it down. Go outside and measure the front, side and back, times it by the height and knock off any doors, windows etc - you don't have to be exact, and I can tell you that half a semi is around 40m2, so £200 ish

Any disabilities in the house? - war pensioners? - family tax credits?

All these are elligible for a 100% grant for CWI

[Mick6]

Thanks.

[Bob Mannix]

Yes very common (in spite of what some "tradesmen" may say). My last house (1928) was exactly thus. They are usually rendered top half as well, to give weatherproofing to the solid construction upstairs. There will be no cavity in the top half. By the time we had built extensions there just wasn't enough cavity to make cavity insulating remotely cost effective.

The ledge round the stairs is very useful when decorating: (a) it will support a platform (old doors or whatever) to work from and (b) it means you can decorate /wallpaper top half then bottom half separately. Almost ideal, I would say!

[Tony Bryer]

I've never heard of this, but until c.1974 the regs allowed 75mm blocks to be used for the inner skin of a cavity at first floor level. The cavity width shouldn't be reduced though.

[ARWadsworth]

Great, as you once did the job then can you please tell me why the CWI installers insulated my gable end in the loft. I assumed this was "dead" space and would not have needed insulating. I am not complaining but just curious. They did a top quality job to my requirements (ie work from inside and not smash any tiles in the kichen)

Cheers

Adam

[Phil L]

All walls must be insulated to the top of the cavity, so the peaks on gables are always done, this is to prevent any water that may ingress from tracking across the top of the 'stopped' insulation - if the cavity is 100% filled, the water will simply make it's way down to the DPC naturally.

We only did peaks from inside the loft if there ws an obstruction outside in the way of the ladders, or if the top was covered in timber cladding etc...sometimes we did them from inside if the ladders wouldn't reach, but we used 36ft ladders so this was a rarity.

All newbuild properties are done from inside prior to plastering

[Mick6]

Well, we just had a quote -- £205 for the side wall and the front. There's a new insulated extension at the back.

Surveyor said it was hardly worth doing as most of the heat would escape though the upstairs walls anyway. He phoned the office and they said he should quote 2-bed bungalow instead of a 3-bed semi to take account of the reduced wall area. (They seem to work on fixed rates.)

It strikes me as quite expensive but on the other hand, gas bills are expensive and the neighbour claimed she could tell the difference after hers was done.

Anyone any thoughts on viabilty? Will it take decades to pay back that amount?

There's no DIY method by any chance...? :-)

[ARWadsworth]

Thanks for that Phil. Just what I needed to know. I actually had all the house done from the inside for cosmetic reasons as the whole house will be reskimmed the next year and I did not want to view the spots on the outside wall where the installers had drilled and then made good the holes.

Adam