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thedresden40
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# Posted: 14 Aug 2019 01:40am
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I'm having some last minute jitters before starting the floor structure on my small cabin:
She will be just 12' x 16', set on six 12" sonotubes. The span between piers is 10' on the short side - with plans to cantilever 1'. The 16' span is bisected by two middle piers, forming spans of 8'. Each sonotube is anchored and epoxied into bedrock at around 2.5' below grade and vary above grade between 1.5' and 3'.
I've been waffling for weeks about the best way to orient the girders that will sit atop the sonotubes; two 16'ers or three 12'ers. The roof will be a steep 16/12 pitch with metal roofing, but with an 8' shed dormer with a 4/12 in the mix. Gable end obviously on the 12' ends. Snow country up here in Maine, although I'm guessing minimal load given the metal and steep pitch.
This will be stick framed with 2x6s (original plans for timber framing this one had to be ditched last month, regrettably) and I would like to utilize a structural ridge beam to keep my ceiling spans open. I had originally thought to span my girders along the 16' ends, but I worry now that the ridge would not be appropriately supported that way, with the half the roof weight landing midway on the largest unsupported span.
Also, is this even a solid design??
I'd love any insight that you all may have. This is my first cabin build and although I'm incredibly excited to finally get this going after months of clearing, I'm more than a little daunted as well ...
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Brettny
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# Posted: 14 Aug 2019 07:29am
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if i gather what your sono tube spacing will be is..your pulling the tubes 1ft under on all sides?
Iwould add another tube on the 10ft span. Guess it really depends on what your support beams are made of. But in all reality another pair sono tube would cost u roughly another $400 and be way easier to do now.
Your putting 6x6 posts on the tubes up to the beams that you will be laying the floor joists on?
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thedresden40
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# Posted: 14 Aug 2019 08:05am
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I'm not sure that I understand what you mean by pulling them under, so sorry.
The thought was to attach the girders directly to the tops of the Sonotubes with J-bolts already set into the concrete. Doubled or tripled 2x12s were what I had in mind for the girders.
I met with an engineer when timber framing was the plan and he felt that the 10' span was not a concern for the 8"x8" sills that he recommended, for what it is worth. Which may be nothing ...
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Brettny
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# Posted: 14 Aug 2019 08:10am
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How are you going to attach a J bolt to a trippled up 2x12?
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thedresden40
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# Posted: 14 Aug 2019 08:36am
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A Simpson 6x6 post base was suggested by a carpenter friend. The original thought was to utilize a horizontal 2x8 mudsill to the tubes and use angles and structural screws to tie that to the beams.
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Brettny
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# Posted: 14 Aug 2019 12:58pm
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I have never seen it done like that. Your also going to have to be dead nuts with the top of your sono tubes or else your floor will not be level.
Have you thought about useing 6x6 posts sitting on sono tubes a few inches above grade? All the concrete can be done with out to much leveling then a string line/laser level/water level ran to mark the height of each post above the concrete.
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Brettny
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# Posted: 14 Aug 2019 01:02pm
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This isnt for a cabin but the same idea applies. Notched PT 6x6 posts through bolted. The first pic is roughly 2hrs from post brackets to laying floor joists.
20190716_060339.jpg
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NorthRick
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# Posted: 14 Aug 2019 04:05pm
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Thedresden40, can you post a drawing of what you are thinking of. I'm not sure I follow your text description.
I have a 12'x16' cabin in Alaska which sees a lot of snow. Mine doesn't sound quite as beefy as what I think you are describing and it holds up just fine. No dormer, 8/12 pitch, and homemade roof trusses.
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ICC
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# Posted: 14 Aug 2019 05:34pm
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Drawings with dimensions are much easier to follow and less likely to be misinterpreted than word pictures. Some of us relate much better to drawings
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