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Nicolle
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# Posted: 22 Jul 2012 10:29pm
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Building a small 16x24 cabin, I have so many ideas about the foundation. Hoping someone could give me some feedback. Small budget, but still want to ensure I have a strong cabin. Thinking 4x6 post sunk in gravel and concrete to the frost line. 6'o.c, so 5 post in a row, and three total rows. Not sure if I should have the floor joists overhang from the beams, or build the two end beams at the edge of the perimeter, and have no overhang. Want to build 2-2x8x12 beams to place ontop of the 4x6 post. Then run 2x6x16 joists over beams. Is this a strong build? Should I use 2-2x10x12 as beams, and 2x8x16 for the floor joist? Should I use a larger 6x6 post, and 3 ply beam. Cabin is just one story, thinking ordering 4/12 pitch trusses wth shingles. Using 2x6 for walls, 2x4 trusses. House will be lightly furnished, so should be fairly light. Any feedback would be appreciated. Thanks for your time.
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MtnDon
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# Posted: 23 Jul 2012 02:15am
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6x6 piers as a minimum IMO. Dig the hole to the frost depth. Try to "bell out" the bottom to make it possible to pour a concrete footer about 16 inches square. Mix and pour concrete about 8 inches deep with some rebar X or # shapes in the middle. Place the piers on that. No need to place gravel in the bottom; that is worse than doing nothing.
Use foundation grade PT 6x6. You'll have to order it; it is usually not that much more than the ground contact grade that is common.
Beams made of two 2x8 would work with pier spacing of 6 feet. Triple 2x8 would let you stretch the spacing to 8 foot.... that depends on your snow load. If 30 PSF or less the above works. If greater it won't. .... Where are you?
Be certain to use lots of bracing between piers and beams and the piers and joists. Most builders using piers do NOT use adequate bracing. Do not count on the earth to provide adequate lateral support. When earth dries out it shrinks and can make piers loose in the ground.
With a center beam you can use common species/grades of 2x6 for floor joists; 16" OC would be best, 24" OC could possibly be bouncy. Placing the floor joists on top of the beams with a 6 inch overlap over the center beam would work. You could also hang the joists between the beams using hangers. That costs more for materials but may make the floor/beam assembly more resistant to lateral loading. That is, the joists hung between the beams may make the beams more stable in lateral movement.
At 16 foot wide rafters are easy to handle. Trusses are convenient though.
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Nicolle
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# Posted: 23 Jul 2012 10:53am
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Thanks for you help MtnDon. I will go with the foundation grade PT 6x6, and stay with the 6' spacing & go with 3-2x8s for the beams. I think it would be easier to just put the 2x6 joists at 16''oc on top of the beams, so i will add lateral support. In rural IL, around 2 hours from St. Louis, so we can get a lot of snow... Do you think this foudation is strong enough for my area? Was thinking couldn't I just knock snow off it becomes too high on the roof? This cabin will be heated, will a 4/12 handle the freeze and thaw cycle? Still unsure on the roof. Thinking 4/12, with 1' overhang just something simple, not interested in a loft or attic room. I have been doing reserch on buiding the roof myself, but since this is my first cabin I am nervous about it. Priced the trusses, and I could save over $500 if I do it myself.
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VTweekender
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# Posted: 23 Jul 2012 12:16pm - Edited by: VTweekender
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We all have snow rakes up here in New England too...it just makes sense to get some off the roof during multiple snowfalls. You really sound like you are more comfortable with the engineered trusses, you probably should go that way if it gives you the piece of mind.....although I would go with a 7/12, the 4/12 should be fine....you could always go with 1" roof sheathing instead of 5/8 or 3/4 if you wanted a little more piece of mind. Your foundation sounds solid with Don's suggestions.
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deanm
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# Posted: 27 Jul 2012 06:21pm
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Hi,
I had to handle an emergency roof repair where I went with roof sheathing instead of 5/8 or 3/4.
Your foundation sounds pretty solid 
Dean
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OwenChristensen
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# Posted: 28 Jul 2012 10:21am
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MtnDon has a good plan. Yes, you can run floor joist out a foot beyond the beam. A 24' long beam can be made from four layers of 2x8's with staggered joints. That's a min. and depends on post spacing. 2x10 are better. Treated wood bend easy. Make sure crowns are up.
Owen
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MJW
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# Posted: 28 Jul 2012 10:48am
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Quoting: deanm Hi, I had to handle an emergency roof repair where I went with roof sheathing instead of 5/8 or 3/4. Your foundation sounds pretty solid Dean
One of the better attempts at spam I have seen here but alas, still a pork shoulder with ham product. 
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Nicolle
Member
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# Posted: 28 Jul 2012 01:17pm
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Thanks for all the help, this site is great! My dream too, living away from crowds and noise & getting to enjoy nature. I am second guessing myself, I keep changing my plans. This site offers so many ideas. I have time, in the Mid West, and right now its to hot and dry to do anything!! Even stopped clearing trees until weather breaks. Thinking now that perhaps I should go with my 6x6 foundation grade at 6' oc, so 15 peirs for a16x24, and bump up to 3- 2x10x12 as beams. Last winter was dry, but we are capable of getting a lot of snow. Or, this seems like overkill. Should I go back to 4 peirs and 3 rows, so 8' oc. I want a studry cabin. Did I mention I have ocd. I would appreciate any feedback...I think until the day I order lumber, my mind will be racing with ideas.
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OwenChristensen
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# Posted: 29 Jul 2012 08:27am
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the cost of a couple piers are cheap , but you can pull them in from the end by a foot and they'll only be 7' 4'' center to center with three.
Owen
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Martian
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# Posted: 29 Jul 2012 09:14am
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Quoting: Nicolle I have been doing reserch on buiding the roof myself, but since this is my first cabin I am nervous about it. Priced the trusses, and I could save over $500 if I do it myself.
Stick building a roof is really easy. Once you have the walls up, string and brace them to ensure they're straight. Screw a vertical support on the outside center of one gable end then cut a short length of your ridge board which gets screwed to the center of the support at ridge height. Pick a nice straight board from your rafter material and make a pattern for your rafters. You'll have a bird's beak cutout where it sits on the top plate and an angled cut where it meets the ridge. The pattern will/should work for both sides. I suggest leaving the rafter tails long just in case you need to make some minor adjustments in your overhang to get the roof square. Cut several rafters and set the ridge. Once you are sure the rafters are going to work, cut the rest of them.
After you have the walls straight, plumb, and braced, you can put up your ceiling joist. Run a strongback down the center from gable to gable to hold the joist straight and to brace the gable ends to. A couple of sheets of plywood can be thrown down on the joist to provide a place to stand while you set the rafters.
Go ahead and put in the collar ties as you set the rafters. Its also a good idea to pull a string between the gable ends just to make sure you stay centered. It doesn't take much to throw the ridge off center; so set your rafters in pairs to help keep it straight. I like to set the ends and center of the run, and then fill in between.
Tom
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