... a. 0.8mm—1.6mm cold-formed steel Roof truss and wall stud, hot dip galvanized surface, Grade ... CHS welded or seamless tube, hot rolled column and rafter, Grade Q345. hot dip galvanized surface treatment ... .2. Fiberglass insulation on the roof and in the wall,a. Roof insulation R30.b ... inside Kitchen.7. Toilet, shower inside bathroom.8. Steel stairs / ladder, or wooden ladder inside if needed ...