Hello,

 

Please forgive the, what must be a very simple question to many on this forum.

 

My contractor has built almost all the exterior walls using concrete blocks, am I correct in saying he needs to now paint the inside of those blocks with a liquid membrane before plastering / putting up stud walls to ensure airtightness?

 

Thank you

SM

If they are being plastered that should suffice.

+1 to plastering but, in case it's not obvious, done after first sealing the junctions with other materials & components

Expanding foam every gap you see where air could get in, but shouldn't enter. Any small gaps use silicone sealant.