Cavity wall construction

[Lawrence Zarb]

does anyone know of a good on-line site giving details of how to construct cavity walls

[BigWallop]

One brick width gap.

External skin / width of brick / internal skin

[Steve Walker]

Conventionally laid in rows, starting at the bottom...

[Doctor Evil]

Why? Why build two walls when one can do. There is nothing in the regs that says cavity walls "have" to be built. The Germans think we are mad. Build one strong skin and use the rest of the space taken up by the other skin for insulation to drop your heating bills substantially. Don't just do what the other dickheads do. Think!

[BigWallop]

But make sure you allow for a moisture barrier between the skins or layers of the wall, or you'll end up with dampness creeping through the outer skin / layer and in to your internal skin / layer.

A ventilated cavity is a simple method to prevent this from happening. Funnily, this is a method also used by the others that laugh at us, so is pretty well a universal method of preventing moisture ingress through a buildings outer skins and insulating materials.

[Doctor Evil]

And make sure the outer skin is waterproof, as with all walls.

Cavities are not universal. Only in coastal wind blown regions are cavities used and the they use render on the outside to seal in the walls; Cornwall, Brittany, etc.

[Andrew Gabriel]

It's not a bad idea to tie them together occasionally too. A number of Wilson Connolly new home owners have discovered what happens when this isn't done...

[Andrew Gabriel]

That was true around 1880.

[Mind Boggles]

Which was about the year Dr Combi's ancestors started filling their bath. It's almost up to the right level (2.73 inches) for him and his ducks to jump in now. Luckily the ducks don't mind lukewarm water.

Nurse Boggles

Managing Director CopperCylinders4U.dot com On the internet super tramway since AD 1734 Suppliers of copper hot water cylinders to the elite ;-) No bath too large, no airing cupboard too small.

[Doctor Evil]

The mind does boggle. Have you tried anti boggling treatment?

[Mike]

For real ? How on earth wasn't that picked up at BC inspection ? And what sort of brickie doesn't use ties ?

[Mike]

Well actually I hate to say this but if you look at all construction processes used around the globe today, IMM is on average correct. Cavities are one way of achieving the goal described earlier in the thread and they work very well, but some places have more over-riding problems such as earthquakes and so the insulating and damp-rejection has to be achieved in a secondary manner to the primary concern of staying upright. There's a lot of housing in the US built to early 20th century European norms which everybody knows will come straight down when the big one hits.

[<me9]

One emlpoyed by a builder under NHBC inspection?

[Andrew Gabriel]

I don't think the BC inspect every house on a housing estate. The BC fees for a housing estate are full fee for the first house, and then only a tiny fee for each identical house. It wasn't just BC that missed it, so did Wilson Connolly's own inspector and the NHBC inspector, but then that really comes as no surprise.

A brickie doesn't use ties if the builder will only employ him if he actually lays the bricks without arguing and the builder doesn't supply enough ties. There was a builder on You and Yours (radio 4) some months back, and he said that houses being built in the UK at the moment are built to the lowest quality he's ever seen during his whole career in the building trade.

[Doctor Evil]

Most on-site trades are not qualified or experieneced, only the gas side is, because of the corgi quals.

[Mike]

Hmm. My dad was a brickie until his back gave way and I think he would have raised merry-hell and walked off the site if necessary. I would have thought the shortage of good brickies nowadays would have allowed the same to happen.

That I can unfortunately believe.

[Mike]

Not convinced on that. A more experienced brickie will lay faster and with less waste so should be worth the extra money.

I think we've heard horror stories there as well.

[Andy Hall]

Can't be. As of April this year, all electricians are as well. After all, your friend Mr. Prescott said they would be and that it would save lots of lives (although perhaps Mr Mandelson told him to say that.. you know.. working him up the back etc.)

[Doctor Evil]

That's right Johnny is good at saving lives. Great fella.

[Doctor Evil]

Still, most are poorly experienced on sites. Most have "picked it up".

Far from the total dross served up by other site so-called trades