Construction of an extension in loose timber

[maah]

I am in full swing with the planning of an extension on the house, which can be read about here https://www.byggahus.se/forum/threads/tillbyggnad-35m-hur-svart-kan-det-va.395747/

Now I would like some feedback on my construction plan to ensure I'm not thinking completely wrong!

The house has already been extended once on piers, so I will continue with that.
This is how I plan to make the floor structure.



Floor Structure

• 12 piers 200mm
• Beams of double glued 45x220 C24 pressure treated
• Floor joists 45x220 C24
• Subfloor boards
• Insulation UNI-SKIVA 35 220mm
• Flooring particle board 22mm

Walls

• Gypsum 13mm
• OSB 11mm
• Horizontal 45mm stud with insulation
• Plastic (Building film)
• Vertical 145mm C14 stud with insulation
• Horizontal 45mm stud with insulation
• Wind protection
• Battens
• Cladding 22mm

Roof

• Truss rafters, to be ordered pre-made
• Insulation UNI-SKIVA 35 195mm (Have not checked how much insulation is needed)
• Tongue and groove boards
• Underfelt
• Counter battens
• Tile battens
• Roof tiles