Insulation on new cavity wall?

[dishman]

What is the correct way to install the insulation when building a cavity wall on a single story extention. Is it best practice to install it as you go and have the cavity wall ties pushed through the insulation?

Or is it best to build the wall first ensuring the cavity wall ties are all aligned and then slide/stuff in the insualtion when the wall is at roof height?

I ask because I am watching an extention go up over the road, and just noticed they had got to roof height and not put any insulation in as of yet.

 

[noseall]

There are several different ways to construct a cavity wall, one of those being 'partial fill' whereby the block-work (or inner leaf) is built first then the insulation is clipped to the tie wires.

In 'full fill' situations we like to build the brickwork (outer leaf) first, then fit the cavity insulation as you build up the block work.

Some builders get a company in to fill the cavities afterwards. Pants method.

 

[dishman]

Interesting,.....so one would assume, if they have built to roof height with both the inner and outer leaf, complete with wall ties without any insulation as of yet....they are going to have to get a company to fill it from the top or inject it in as if it was an existing cavity wall? They will have to use those polystyrene balls I guess? Why would a company do it this way round?

On the subject of partial fill and full fill, which is considered to be the most appropriate? Or is this one of endlessly debated questions?

One would assume that (as long as the thermal properties are the same) a partial fill is better for limiting any moisture transfer/future issues as there is still a "cavity" in the "cavity wall". Or does the material used in full fill solutions negate this possible problem?

 

[stuart45]

Why would a company do it this way round?

It is sometimes done on site. They reckon it works out cheaper.