I am going to install a ceiling, the span is 3220 mm (approximately 
). The ceiling needs to support 30 cm of insulation weighing around 10 kg/m2. Additionally, there will be battens and plasterboard adding about 15 kg/m2. (see https://www.byggahus.se/forum/threads/hallfasthet-innertak.433128/). So, 25 kg/m2 in total, plus the weight of the beams themselves.
There is an inspection hatch above the insulation that you can crawl into, but it's not big enough to store anything.
Referring to https://www.byggbeskrivningar.se/dimensionering/golvbjalklag-inne/ with "0" self-weight and "Förråd" (storage), at least 45x195 C24 with cc 1200 is required. The load is then calculated to be around 150 kg/m2 (based on support reactions)!
Even if you want a bit of a margin, I'm wondering if 45x195 might be a bit over-dimensioned for supporting a ceiling?
). The ceiling needs to support 30 cm of insulation weighing around 10 kg/m2. Additionally, there will be battens and plasterboard adding about 15 kg/m2. (see https://www.byggahus.se/forum/threads/hallfasthet-innertak.433128/). So, 25 kg/m2 in total, plus the weight of the beams themselves.There is an inspection hatch above the insulation that you can crawl into, but it's not big enough to store anything.
Referring to https://www.byggbeskrivningar.se/dimensionering/golvbjalklag-inne/ with "0" self-weight and "Förråd" (storage), at least 45x195 C24 with cc 1200 is required. The load is then calculated to be around 150 kg/m2 (based on support reactions)!
Even if you want a bit of a margin, I'm wondering if 45x195 might be a bit over-dimensioned for supporting a ceiling?