a2thak
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# Posted: 20 Jun 2012 18:19 - Edited by: a2thak
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Hello, I am getting the plans started on a 16'x24' cabin I am looking to build in the mountains in Colorado. I have a good build site in mind, and a pretty good idea of how I want the cabin designed, but some of the smaller details are getting me overwhelmed. I have spent LOTS of hours combing and searching this site, and have found lots of usefull info. It will be up high in the mountains, and as best I can tell I should plan on at least 100 fpsf of snow load in the winter. So it needs to be beefy.
Here is my plan so far:
12 concrete sonotube piers dug below frost line (deep ~48"). Four piers along each 24' length, three total rows.
I was thinking of using brackets to attach 6"x6" piers to each tube to raise the floor up anywhere from 3-4'. Cross brace each pier with 2x10"s.
Then, use 6"x6" to make a timber rim (using a half lap corner joint) as well as one 6"x6" down the middle lengthwise. So 3 6x6s lengthwise and two 6x6s widthwise.
Then, attach the 2x12 beams and joists spaced at 24" (so I can add lots of insulation) on top of the 6x6s, giving me a max span of only 4'10" across the width from the rim to the center beam.
First off, is that too much?
However, I still have a lot of questions:
1. If I want the piers to be in the center of the corners of the 6x6s, do I need to subtract the 3" off each side? That would make the piers 94" apart, and a total length of 23'6" center to center of the piers. That way, I would place the 2x12s on the outside rim of the 6x6s and not have a lip.
2. How would I attach the 6x6 rim to the 6x6 pier? Also, how would I attach the center 6x6 to the width 6x6s right where the pier connects?
3. What about mounting the 2x12 to the 6x6?
Thanks, and I'm sure I will have lots more questions.
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adakseabee
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# Posted: 22 Jun 2012 20:57
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a2thak, here is how I would go about solving your design problems:
1. The horizontal 6x6s are unnecessary for a 1 or 1 1/2 story cabin, unless you plan on using your building to store heavy equipment. In that case, you'd be better served building it with the first floor at ground level. It you feel that it must be elevated and built like Fort Knox, I'd recommend timber framing where the 6x6s are joined using mortise and tenon joints, both the vertical to the horizontal 6x6s and the horizontal to horizontal 6x6s. For a timber framed building with rough framing dimensions exactly 16 feet by 24 feet and the 2x12 joists constructed directly on top of the horizontal 6x6s, the vertical 6x6s would be set so that the distance between adjacent outside corners would be 16 feet on the short side and 24 feet on the long side with the intermediate verticals aligned appropriately. If you have your 4 corner verticals set properly, the diagonal distance from one outside corner to the opposite outside corner will be 28.84 feet (28 feet 10 inches). If both diagonals are the same dimension, your building will have square corners.
2. However, timber framing using the classical mortise and tenon joints may be a little difficult. For a cabin, I would simply not use the horizontal 6x6s. Rather, to form the equvalent of a beam, I would "let in" one 2x12 into the vertical 6x6s on the outside (facing outward) surfaces of the perimeter 6x6s along the 24 foot sides. The 6x6s would be cut such that the 2x12 would be supported on the bottom by the 6x6 and its exterior face flush with the vertical 6x6s. On the inside surfaces of the long side verticals, I would fasten another 2x12, also let in to the 6x6 so that the 2x12 sits flush with the inside surface of the 6x6. I would fasten fasten the 2x12s to the 6x6s using Timber Lok screws (or equivalent). I would also use hot dipped galvanized 20d nails to supplement the screws. The top of the vertical 6x6s would be cut flush with the top surface of the 2x12s. On top of the 2x12s I would then nail a 2x6 across the upper surface of the 2x12s and vertical 6x6s. In essence, you would then have three 24 foot long beams on which to build your floor. On top of all three 24 foot lengths, I would then add the 2x12 floor joists. Using 2x12s for such short spans (8 feet) is overkill unless the added space for insulation is desired. Before you add your deck material to the floor joists, you may want to attach on the underside of your 2x12 floor joists appropriate screening material of sufficient gauge to keep varmits at bay.
I would also use galvanized metal stapping that spans the vertical distance from the vertical 6x6s across the 2x12/2x6 "beam", the 2x12 floor band/rim joists, the subfloor, sill and at least a foot up the studs, at every exterior vertical 6x6.
A final note: since you will most likely not find 2x12s 24 feet long, ensure that where you join two horizontal 2x12s at a vertical 6x6, on the opposite side the 2x12 runs clear through. In other words don't join all four 2x12s on the same 6x6! And by all means, cross brace as you have planned!
I hope this helps. They may not be "perfect" solutions, but they will work. Good luck! - Adakseabee
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