Joist into wall

Hi,

Soon I'll be adding joists to my extension and wondered if anyone had some advice.
I have seen suggestions of a ledger board and hangers, I have also seen people suggest cutting a hole into the existing wall to rest the joist on there. The latter sounds the most structurally sound.

If I did do this, would the joist just need to go circa 100mm in, wrapped in DPM and then mortar into place?

Thank you

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No need to double post. Mod.

You will get more replies if you put this in the building forum. I think you need silicon mastic to ensure the wall is air tight after placing the joist in the pocket

Blup