Cavity wall blown insulation problem?..

[tony sayer]

Wonder if anyone knows anything about the following. Our gaff was built in 1979 and the first thing we did here was to have the cavity walls filled with blown insulation which has improved the heat loss.

One of our neighbours has just asked who did ours as the two firms they had in to quote said the cavity "wasn't big enough" to do that with blown fibre. Can't remember who did outs a long time ago now. Cavity here seems around a couple of inches, surely thats enough?..

Anyone else had that problem or heard of it?..

Cheers...

[Harry Bloomfield]

tony sayer used his keyboard to write :

I thought 2" was standard? Our is 2" and was done around 10 years ago without any problems. The insulation was blown in via holes drilled at

1m or so intervals.

[dom]

Possibly certain types of insulation are unable to meet the building regs spec for minimum insulation when upgrading a thermal element - with only a 2 inch thickness.

[js.b1]

If you read the regulations re insulation you will find it is subject to "reasonably practicable".

- It is unreasonable to expect someone to demolish an outer leaf so as to rebuild it to a modern size.

- It is however reasonable to require someone building an extension to build it to a modern size.

For cavity insulation there are limits on depth (minimum & maximum), obstructions, not wet, not unconduited cables, not shared with a chimney, not bridged by bricks etc. So ask them why in writing, because it sounds like typical word-of-mouth misinterpretation of building regulations.

[andrew]

What size holes? Can one insist the holes are made through the mortar joint wheere three bricks meet?

AJH

[Harry Bloomfield]

About 3/8".

Ours were all on the joints. I don't think you would actually need to insist, much easier for them to drill mortar than brick anyway.

[Steve Walker]

Ours were done on the mortar lines, the drill was just larger than the mortar bed, but when filled, it's pretty well invisible even if you know it's there.

SteveW

[Andy Cap]

The front of my house is part tile hung and the rest has very narrow mortar joints which I didn't want disturbed and so I requested that it was done from inside. Fortunately, most of the was emulsioned, so not a problem sorting out the holes.

Andy C

[Tim Lamb]

Thread hi-jack alert!

My wife owns a ground floor flat in a '60's built block. AFAIK the construction is concrete frame, brick exterior, block inner leaf and probably a 2" cavity.

The long cold winter has brought huge problems with internal condensation on North and shaded exterior walls. Trying to convince tenants to ventilate and put more heat in is fruitless so she is considering an approach to the management committee regarding insulating the cavity.

It may be that the concrete frame closes the cavities at each floor so issues with neighbours may not occur but are there any more problems to consider?

The wiring is buried steel conduit so unlikely to be found in the cavity. Mortar bridging on wall ties would have to wait for a survey but... anything else?

Best system to use?

regards

[TheOldFellow]

Mine was done five years ago, and then we told the cavity had to be a minimum of 50mm. My test bores were 45-75 so the engineer said he would allow it. I have to say that it is not entirely a success, there are places where I find areas with no fill often close to corners. So now I am, room by room, adding internal insulation of 25-60mm Celotex on the outside walls.

R.