Quite a few more to go - but we decided to install a small number initially to check our work.

M 12 100 dynabolts used where possible, with M 12 60 (as per spec) being used where reo bar hit.

Calculation of the column heights took a lot of careful work.

First, I used a laser level to survey all the column mounting points on the slab.

I designated the middle position between the two roller doors as a 0 datum point and recorded all other positions relative to this.

The laundry area is 100 mm higher than this point and this has been allowed for when calculating discrepancies.

See pink boxes on the diagram below.

Next I calculated the required steel frame wall height:

Finished floor level for the main floor is 2700 relative to the laundry floor. Subtract 100 mm for purlins and 20 mm for floorboards - gives a frame height of 2580 mm.

The garage area has a floor that steps down 100 mm so the frame height here is 2680 mm

Most of the columns have a 5mm plate at the top and a 5 mm foot at the bottom (except top RHS #1 which has a 12mm foot) - so subtract this off frame height for most columns.

Some columns also have a U beam on top (subtract 304mm) or a PFC 150 on top (subtract 150)