Extension build Questions

[catlad]

I am helping to build an extension for my father in law and the bricky has asked for a 50mm gap to be cut in the existing house wall, here the new wall will start with wall starter kits.
My query is does this gap need to be cut if it is going to be rendered afterwards?

 

[23vc]

I did that and didn’t cut a gap, for both rendered block and facing brickwork. I know some will say it’s essential but I hardly ever see it done around here nowadays. The wall starters just get bolted on and off you go.
I know cutting a gap is better in theory but the BCOs round here don’t seem to require it, rendered or otherwise.

 

[SpecialK]

This should be a question for building control. Some like the cavity continuous. Some like a slot cut all the way through. Some like a slot with DPC inserted.
It probably depends how weathered the wall will be too..

 

[catlad]

Thanks guys I'll call building control and see what they say!
The bricky doesn't know it will be rendered and I didn't want to just cut it and then find out it wasn't necessary as its quite messy.