I'm keen to stay on top of the airtightness as I move forward with the 1st fix and beyond. I am new to thinking about most of this for forgive the inexperience.   I'm thinking of leakage as being mostly through surfaces and edges/junctions.   Surfaces: wet plaster on the blockwork walls (GF and FF) wet plaster on the plasterboard 'walls' and ceilings of the attic liquid screed on GF and FF Windows themselves are constructed with a good L-value and