Father-in-law has a garage that is maybe 5m wide and as long as the house. There is a deck on top. Now everything is rotten and ready to be demolished. It was probably a jerry-built construction. The wood and insulation in the roof are moisture-damaged deluxe. Seems to have run down along the wall. It is of course not used. But I'm considering helping them rebuild it. I assume it should be glulam beams across. I can of course talk to the professionals, but I got curious about approximately what size the glulam beams should be at a minimum? And what spacing (cc)?
Yes, anything other than glulam does not work. The dimensions of the beams and the c/c spacing are related. The larger the c/c, the larger the beam and vice versa. If you place glulam beams transversely (with a 5 m span) at c/c 1200, they should be 90x315 mm. If you go down to c/c 600, 90x270 mm is sufficient. If you go up to c/c 2400, 90x405 mm beams are required. Calculated with a useful load of 3.5 kN/sqm for the deck. Since construction timber is significantly cheaper than glulam, it is possible to find an optimal c/c distance for the glulam beams.
https://www.byggbeskrivningar.se/dimensionering/med-meny/?cid=689
There is a simpler dimensioning program
There is a simpler dimensioning program