Hi, I'm building a shed; 10 x 5 metres on a farm. It consists of. ● 10 piers 600 x 750 ● Perimeter beams 300x450 ● 1 Internal beam 300x450 The piers start at the bottom of the beam. I have done all excavations. Soil H2. My questions relate to vapour barriers. 1/ If I pour the piers first and drill/g...