Hello, planning to expand at the summer cabin. There are 2 buildings standing 4 meters apart and in between there will be a kitchen measuring 4x3m. I have started digging and casting posts, with about 2 m ± 20cm between the posts depending on the size of the rocks in the way. I had planned to use 45x145 as beams/floor joists and joist hangers to achieve a low building height and match the floor level of the existing buildings. The interior floor will be 33x175mm pine floorboards screwed onto the floor joists. I'm starting to doubt if 45x145 is sufficient. Maybe doubling the 145 on the beam will suffice? And how closely should the floor joists be placed? I'll check if it's possible to go up a dimension or two.
With two 4-meter carrying beams, pillar distance approximately 2 meters, and 3-meter long floor joists with a center-to-center distance of 600 mm, you need to use 45x220 C 24 throughout. If you want to manage with 45x145, you must both reduce the pillar distance for the carrying beams to about 1.3 meters and add a third carrying beam in the middle that supports the floor joists (then 45x120 will actually suffice).
The deflection is the biggest issue when it comes to floor joists. If you add a screw-glued chipboard floor, 45x145 C 24 on c/c 300 is sufficient. But that's a waste of the sturdy floorboards.
Double 145s for the beam are not enough, you need to go up to double 45x170. If the height is sensitive, you can always special order glued laminated beams 140x145, which are sufficient. Alternatively, you can buy ready-made 140x180 and rip them down if you have a good saw. It must be laminated wood of the homogeneous type, with all laminations equally strong.
Double 145s for the beam are not enough, you need to go up to double 45x170. If the height is sensitive, you can always special order glued laminated beams 140x145, which are sufficient. Alternatively, you can buy ready-made 140x180 and rip them down if you have a good saw. It must be laminated wood of the homogeneous type, with all laminations equally strong.
