Marking out location of wet area for H3.2 joist and H1.2 for the rest, spacing of joist is to 400mm centre. Make temporary fixing to joist by putting one galvanized nail on each end as it may have to be moved later on

Laminate double joist at both end of the building, joist can be laminated with H3.2 on the outside and H1.2 inside

Run string line on BL from profile and fix double joist according to the BL, then set all centre joist in place using 20mm batten aligning method, run the string at end of boundary joist over 20mm block then fix joist according to string line