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DaveBell
Moderator
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# Posted: 3 Aug 2018 03:44am - Edited by: DaveBell
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I was thinking of making a cabin floor like a deck.
This is an 8' by 8' grid. In the corners are 4"x4" PT in the ground. There will be 8 of these grids making a 16x32 cabin.
The perimeter 4x4's go to the roof and carry the roof load. Shed type metal roof 2x10x18's, 16 OC, will span 18-5 for the 16' design.
The interior 4x4's will be cut flush to the joists. There is no roof load for the walls that are built on the floor between the 4x4's.
Floor Joists. Should I use 2x6's on 2x8's or 2x8's on 2x10's? The dark colored joists carrying the other joists by screws or hangers.
Should I hanger them all which might be overkill, or just hanger the ones that connect to the 4x4 posts and screw the light ones to the dark ones?
Can hangers alone support the interior live load?
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Princelake
Member
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# Posted: 3 Aug 2018 09:05am
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I'd be running a beams the full 32' length.Also others will say to upsized to 6x6s. I would use cinder blocks off whatever base your using on the ground as peers so no wood is close to the ground. Then I'd put in beams. 16' is bit of a span and might be bouncy. I would add a beam down the center. Most on here would say 2x10 for but with a center beam I'd just use 2x8 to save a bit on costs. Also for the roof have you looked into engineered floor joists instead of 2x10x18? With 18s you won't have a lot of over hang and go with say 20s. And typically longer the length of wood the more warped and twisted they will be. I'd use hangers only in the corners. I would also use nails instead of screws for the floor joists faster with an air gun and nails bend if there's movement and screws break that's why you doing see framers screwing houses together
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Borrego
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# Posted: 3 Aug 2018 10:45am
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Dave - why don't you use 16' floor joists and set them on top of the support girders? easier, faster, cheaper, and I think stronger. I know that we don't do that anymore because of the popularity of Simpson hangers. You will have to block them every 4 ft....
+1 on using nails.....
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ICC
Member
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# Posted: 3 Aug 2018 05:29pm - Edited by: ICC
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Quoting: DaveBell I was thinking of making a cabin floor like a deck.
Why? You are planning on a cabin, not a deck.
I don't understand why you would try to reinvent the wheel, so to speak.
The idea of running the piers up through the walls to the upper wall plate has some merit for stiffening the structure. Using 4x9 or 4 x10 OSB sheathing, vertically over the exterior would tie the piers/posts, floor and walls together nicely. However, that may carry some difficulties as well; such as how does the floor weight get transferred to the piers? Simpson brackets? Notches in the piers if the piers were 6x6?
FYI, grade #2 in just about any common construction species can make floor joists that span 16 feet on 16" centers with a deflection of L/360 or better using the std 40 psi LL. That does away with a center beam which is not needed for most cabins unless there is a plan for some extra heavy floor loads. Big gun safe, hot tub, etc.
I like stacking joists on beams, as long as good blocking is used between the joists to prevent rotation of the joists. The IRC calls for solid 2x blocking every 8 feet (minimum) for joists 2x10 and taller.
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ICC
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# Posted: 3 Aug 2018 05:47pm
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Quoting: DaveBell Can hangers alone support the interior live load?
Simpson has a joist hanger selector webpage. Insert loads, etc and they make a recommendation. As well they have published tables with both upload and download specs for the different size hangers they make. IIRC a 2x10 on simpson hangers is good for well over 1000 pounds. Their specs spell it all out and include fasteners types, sizes and numbers.
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DaveBell
Moderator
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# Posted: 3 Aug 2018 06:38pm - Edited by: DaveBell
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Quoting: ICC Simpson has a joist hanger selector webpage
Been there. 2x8, LUC26Z, Floor(100), What does 845 mean?
https://www.strongtie.com/products/connectors/wood-construction-connectors/technical- notes/face-mount-hanger-loads/solid-sawn-df-sp
I have already built a smaller version, (12x18) only $600.00, county approved the design, used as a rain shelter. WHY? It's a simple approach, tall PT from ground frost level to the roof. I had friends say just close it in. So I'm expanding the concept. No wall spreading, no trusses, etc.
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DaveBell
Moderator
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# Posted: 3 Aug 2018 06:49pm - Edited by: DaveBell
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Quoting: Borrego why don't you use 16' floor joists and set them on top of the support girders?
That would be even simpler. I made that change to the drawing as an option. Thank You! After I figure out the hanger capabilities. I would not have rim board, but hurricane H1 hangers like in the picture above and blocking would go in. So in that approach, 6 hangers for the 2x10x8 beams would take the live load for 8x16 of the floor. Then repeat across the 32' length. In my 8x8 initial approach above, Live load for 8x8 was transferred to the hangers/piers. So lets see if ICC can help me decipher the hanger table.
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ICC
Member
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# Posted: 3 Aug 2018 07:13pm
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Quoting: DaveBell What does 845 mean?
845 pounds vertical down load per connection bracket
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