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Alpine_Junky
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# Posted: 29 Apr 2020 02:02pm
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Anyone see any major flaws in the planning / design? I did a ton of research on this site and this is what I seem to be pulling together as a viable plan.
Cabin Size: 32' wide X 52" long
Single Story
Foundation; 18" sonotubes, soil is around 2500-3000 psi. 24 piers planned with greatest span being 10" apart going long ways and 8" width. Piers will be out of ground about 20" to give some access. OSB sheeting under cabin to protect floor insulation. Anyone know if I hold the piers up that far if they will need cross bracing? They will be sunk at least 4' deep. ...cont
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Alpine_Junky
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# Posted: 29 Apr 2020 02:04pm
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Floor Framing: 2x12; Center beams will be 5 2x12s and rims 2 thick. 50' will be continuous with cross bracing notched in.
Floor: 2X10 joists over; 16" O/C; 3/4 OSB sheeting
One thing I can't find much info on is if its better to use hangers and forgo the joists resting on top of the framing. Any suggestions? I know this would save some weight and expense. My preference is for the cabin to sit a bit higher off the ground as it really opens up to a nice view.
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Alpine_Junky
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# Posted: 29 Apr 2020 02:05pm
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Walls: 2x6x10; 16" o/c; 7/6 OSB sheeting which will later be covered by 1" board and batten on the outside, some drywall and some wood on the inside.
Roof: Going to spring for engineered trusses; 8/12 pitch, 20' will have attic and 30' of roof will have 4/12 scissor. 7/16 sheeting; Metal roof. L240 deflection rating achieved because of the higher snow loads; northwest Montana.L360 was just too cost prohibitive. Discussion with engineer was that wood T&G would be better choice for ceiling finish. He had no concerns on L240 vs L360 and cited multiple homes I know of in the area that they built like trusses for.
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Alpine_Junky
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# Posted: 29 Apr 2020 02:07pm
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Windows and doors installed throughout. Got a deal on a house full of premium widows. Some as large as 5x6. Plan was taller walls will accommodate and allow proper header installs & aesthetics.
I used span calculators to check loads for wood types, etc. and everything seems to be well inside the allowed limits of #2 grade, figure for the extra few bucks, I am going to spring for a lot of SS.
Location is Northwest Montana at 3k elevation. Outside of town and where local permits are not required & no inspections available. Off-grid with no electrical available (cistern going in the ground nearby soon with surface water rights). Source of heat will be near unlimited wood from keeping property cleaned up.
Thanks a ton for any feedback! Would also be grateful if anyone with this sort of experience might mind lending me a Q&A phone session. Trying to do this on my own & feeling a bit overwhelmed. Investigated hiring a local builder but that is not in the cards for a number of reasons.
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Princelake
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# Posted: 29 Apr 2020 06:53pm
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If you have all your material there you can use whatever to just temporarily brace your sonotubes if you have to. No need for permanent bracing.
If I were to sheet the underside of consider using pressure treated plywood.
It's faster easier and easier not using hangers. Putting floor joists on top does give you more room for when you have to crawl under there.
Sounds like you have things pretty well figured out.
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Brettny
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# Posted: 30 Apr 2020 07:55am
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It sounds like you have a good plan. If you backfill the sono tubes you will not need to brace them.
What are you useing for your concrete to wood connection? Are you knotching the vertical post to accept the main girters?
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Alpine_Junky
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# Posted: 30 Apr 2020 09:51am
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Thanks for the replies!
The pressure treated plywood -- will check to see what is available. I was kicking that idea, or at least exterior grade ply, around. It is in a pretty dry area and I will have a vapor barrier with some very fine crushed stone / sand on top of.
For the vertical connections, I was thinking that if I held the sonotubes about 20" or so out of the ground I could place a pressure treated plate on top of and then set the 2X12 on top of the pressure treated plate and then stick some rebar into the concrete. I would join the 2x12's together where they intersect via notching & was kicking around the idea of also bolting them with a simple piece of angle where I'd weld a gusset inside to give it strength if I went with the idea of placing the floor joists above this framing.
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Brettny
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# Posted: 30 Apr 2020 12:16pm
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Your going to have the top of the sono tube be the bottom of the girter? Leveling that amount of concrete piers can be very hard and dosnt allow for much if any adjustment after the fact. I would use posts on top of the sono tubes, less concrete and you keep the floor joists a bit further away from concrete. That's my preference.
18in round sono tubes with 20in sticking out of the ground.. that's an extra 156 60lb bags of concrete above the ground. Also if any part of the top of concrete gets splashed with water it will end up on your wood. Keep them under the building.
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Alpine_Junky
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# Posted: 30 Apr 2020 12:40pm
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I remember seeing the posts in another build I was trying to borrow some design off of; would you reckon 8x8 pressure treated with the metal connectors? Seems like it would be easier to work with. Would I need to gusset / brace these together or to the framing?
I have use of a laser level, derrick digger for tubes, & can get concrete in via truck -- was thinking that use of 2x12 pressure treated on side would compensate for any variances -- but I would really need to get things very close (this step has been one I am most nervous of for the entire build). Thank you!
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snobdds
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# Posted: 2 May 2020 10:43pm
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I did pretty much what you want to do. I used hangers on all the floor joists, I like a lot of metal in the build. It sounds like you got a plan all planned out. I'm in Wyoming so I know the conditions and I know the summers are short. I spent one entire summer just on the foundation. Timeing of the build will be critical, that's how it was for me.
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