Reduce Cavity? Facing bricks wider than engineering

[matlob]

Hi

Looking for a bit of advice

I have got up to the slab level for an extension and the only facing bricks I can get to match the property are 115mm wide. I should have sourced before I know but they are all different sizes currently and these are the best match possible!

Am I ok to have the internal blocks sit 15mm over the floor slab to maintain the 100mm cavity or should I just reduce the cavity to 85mm?


Thanks

 

[^woody^]

Yes, put extra ties for the first and second course of blocks. And if you are building the inner leaf after the outer, and have full fill insulation, consider laying the first two course, cover the top ties with a spot of mortar, and let that go off before building higher. This stops the bottom courses sliding on the DPC/DPM

Also bear in mind the tendency for walls to be built slightly out of plumb (towards you) as you start to get above shoulder height.

So does it actually need the full 15mm projection? Will the insulation compress a few mm instead

 

[matlob]

Thanks Woody

I've not got the insulation batts yet so could go with 85 and keep the walls inline but wasn't sure what was best.

Not sure if I need to keep 100 cavity though for BC, although they're not that fussed what I do by the looks of it. They've said to get the roof on before the next check.

Maybe just move it in a few mm on the internal and out a few mill on the external? The wall i'm joining isn't totally plum on the external so that may bring it out a bit too

Also do I put a tie on top of the bricks at slab level to stop the insulation falling in the cavity and maintain the gaps for brick/block as I go up?

Thanks!