I am planning a shed construction and have decided to use rafters resting on a ridge beam. The shed will have the dimensions 4.8x3, and I will use a 66x315 ridge beam (according to the sizing guide on byggbeskrivningar.se), see image:
The problem is that I would like to have a door on the gable end to drive in a riding lawn mower, etc., and I need to relieve one of the posts that the ridge beam rests on. The door will be around 1.3-1.5 wide. The rafters will be 45x120, and I will have an uninsulated metal roof.
However, I have no idea what dimension I need for this beam?
OK, screw or nail together two 45x95s that you set as posts on both sides of the door opening. Nail or screw fairly closely, say every 15-20 cm, and preferably use waterproof glue (regular white glue - outdoor). Also make a similar post (of 2x 45x95) that goes between the beam and up to the ridge beam.
Then make the beam of two 45x220 nailed together in the same way (but here gluing and tight nailing/screwing is not as important).
I haven't calculated this in the slightest, but I feel quite sure that it is not undersized. The construction (the beam and posts) should take a snow load from a maximum of 2.4x4 meters of roof area. Now I don't know which snow zone you're in, but Västerbotten may certainly involve 3 - 3.5 (but probably 3), which gives a load of about a maximum of 3 tons. So it should be fine.
p.s., inspect and use good quality lumber for the beam and posts.
