Ime with a prev 12x24 build c/w a 12x12 stand up in the center peak loft was that in the summer it was often too hot for comfy sleeping and in the winter too hot because the stove heat rises. For a loft floor, the joists would need to be bigger, closer together or span a shorter distance. That is solely when the ceiling joist is only supporting a ceiling. That would need a midpoint support on each rafter. Quoting: jsroreceiling joist to tie the walls together my plan to span the 30' was (2) two 20' 2x8 nailed and glued put on 24" center.Ī 2x8, #2 Doug-Fir ceiling joist, 24" OC, has a maximum span of 14'5" with a 20 PSF snow load. The number of nails or structural screws must be the same as whatever number and size are recommended for the rafter heel to ceiling joist joint. If close to a max or min it never hurts to be more cautious and round upwards for more strength.Ĭeiling joists can be spliced but the splices should only be above a wall. The spans given are the maximums and the lumber sizes the minimums. You also need to know the lumber species and grades that are available to you, the pacing and so on.įor rafters with a pitch greater than 3:12 use the deflection limit of L/240 unless there is no finished ceiling attached to the rafters. Some people have had issues with the app but it usually works fine for me and the webpage link always works as far as I know. There is the webpage version and there are also Android and iOS versions. Then you can either use tables or try the AWC span calculator. I would check that with the state of a reputable web source. Who knows when a big storm may dump a truly big load? There are areas in ID where the snow load is much greater. The minimum figure used by anyone anywhere is 20 PSF. It is very important to know the average snow load. Quoting: Grizzlymanspanning 15’ horizontal a 2圆 may not be enough for a rafter. I don’t have the charts in front of me but you may want to consider beefing that up to a 2x8- especially in Idaho with the snowload # Posted: 18 Sep 2023 13:59 - Edited by: GrizzlymanĪlso, I think if you’re spanning 15’ horizontal a 2圆 may not be enough for a rafter. I’m Just thinking that if you moved the wall for the 23’ span and made it a 22’ span (or even 21’) then you could join that rafter tie and a shorter one on top of an interior wall and the joint wouldn’t matter then. The joint might be troublesome on a longer spans with two nailed together?Īlso- just a question but why 23’? I was able to find 22’ 2x8s when I did mine. Could be the tension of the triangle that holds it taught- not sure. Not sure about a 23’ span but I can tell you that my22’ rafter ties are 2x8 and haven’t sagged at all in 2+ years. The other kicker - my wife wants a loft i dont think its doable with out a beam/support down the middle of the cabin, then i assume i would need to support the floor were the beams would rest. Will this be too much and get a sag in the middle? it will be supported by the interior walls, the longest span for a few joist would be 23' and 2圆 for rafters, ceiling joist to tie the walls together my plan to span the 30' was (2) two 20' 2x8 nailed and glued put on 24" center. Hi, we just started building our off grid cabin in Idaho, foundation done and outer walls are up. Small Cabin Forum / Cabin Construction / 30x32 off grid cabin-ceiling joist/roof question Forums - Register/Sign Up - Reply - Search - Statistics.
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