I want to fix beams around the walls of an old granite barn to form an upper floor area. I've worked out my joist spans etc but as the walls are uneven I am in a quandary as to how to fix the side beams to the walls (approx 600mm thick). My idea is to drill through the granite walls and bolt the beams to the walls using threaded bar (20mm?) with plates on both sides.
The beams will be around 4.2m long and 197mm H x 75mm wide.
At how many points should I fix each beam through the wall and is 20mm bar suitable? Will I need any down supports or will the beams be strong enough (there will be a CLS frame under them)?
Any help gratefully received.