Cut two end piece of jack studs to height and brace fix on to the soleplate

Use the same method again with 200mm batten and run a string line over on top of the jack studs marking out level of all other jack studs then cut and fix align to string line

laminate barer 2 galvanize flat head 100mm nails skewed at spacing of 60mm from each end of different piece of timber and then 150mm centre onward