Tying thermalite blocks to 73mm bricks...?

[jh3141]

Been looking for recommendations on this problem for the last hour or so, and am getting thoroughly confused. I'm building an extension with 73mm bricks (so that they match the existing 1930s-built house) and thermalites on the inner leaf, which means of course that I'm not getting good alignment of my courses. I'm also using celotex-type rigid insulation boards, which seems to complicate matters a bit, as the insulation boards won't sit right with bent ties. I've seen a load of different recommendations:

* Just bend the ties and fit the insulation as best I can (although a small minority seem to think that bending the ties should always be avoided, it is often suggested and the recommendation of the tie manufacturer I've been using so far is "do not bend them in place" which suggests they accept installing them bent as long as you prebend them)
* Use helical ties that hammer into the thermalites (although this seems a lot more expensive -- the best quote I've had so far is in excess of 60p per tie, compared to the 8p per tie I'm paying for traditional ones)
* Put the standard ties into the perps -- they'll need twisting 90 degrees for this to work which is a lot of effort, and I'll have to put one every 450mm rather than the 600mm spacing I've used so far
* I've also seen mention of adjustable ties, where one half can slip vertically some distance from the other, but haven't been able to find a supplier of these.

What does everyone reckon is the best option?

 

[wessex101]

For a residential extension I would go for a combination of 1 and 3 and maybe put a few extra ones in to compensate. Obviously it is not ideal but you can make a small slot in the celotex to take the bent tie but try to get the insulation clip as vertical and tight as possible.

Stainless steel wire ties bend quite easily just make sure they always slope down towards outer leaf. (sorry if that was stating the obvious)

 

[Architexeter]

perps

 

[tony1851]

Personally I wouldn't put them in the perps as the mortar there is nowhere near as well-compacted (and therefore less dense) as it is below the brick.
The resistance to pulling out would be a lot less.
Just use the normal twisted ties and pre-bend them, and cut a little out of the board if necessary to accomodate them. You won't get cold bridges and condensation.

 

[noseall]

I'm building an extension with 73mm bricks ......I'm also using celotex-type rigid insulation boards, which seems to complicate matters a bit, as the insulation boards won't sit right with bent ties.

...begs the question.

Why use rigid partial fill insulation when there is a simpler full fill alternative which would sit better with the out of kilter coursing?

 

[limerockconstruction]

I'm building an extension with 73mm bricks ......I'm also using celotex-type rigid insulation boards, which seems to complicate matters a bit, as the insulation boards won't sit right with bent ties.

...begs the question.

Why use rigid partial fill insulation when there is a simpler full fill alternative which would sit better with the out of kilter coursing?

+1

 

[trowlerman]

agree use full fill insulation better job anyway