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Small Cabin Forum / Cabin Construction / Just a few questions before it all starts
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stitch
Member
# Posted: 12 Feb 2013 23:06
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Well the site have been cleared and would like to haul in most of the materials before winter is over. As I have said before the property is only accessible via atv so hauling the bulk of the stuff out before spring time would be the best. This is what we are thinking as of now.

The "Shack" is in Central MN and too rocky for posts, with the remote location and the use of atvs and a boat trailer for moving the lumber so it will be built on skids. The prices are current from the other day. Just trying to keep a tab on the building cost. But this will at least get it off the ground and a good start so it will be all dried in by summer, if not in a couple of weekends after it starts.

4" Concrete Blocks Double stacked every 5ft 16 on each side.
$0.94x40=$37.60

2 skids made of 3 Treated 2"x8"x20' glued and nailed.
6 2"x8"x20' @ $24.69each x6=148.14

Floor Joists 12" OC 2"x8"x16'
20 2"x8"x20' @$12.48 =$249.60

Rim Joist 2"x8"x20'
2 2"8"20' @ 15.99 =$31.98

Floor 4'x8' 5/8" CDX Plywood
12 @ $18.37 =$220.44

Total as of Feb 7th
+/- 687.76

60 Cases of refreshments
=Priceless

The skids will be placed 1ft from each side so the total floor span will only be 14ft. I do have a few questions as putting the list together. Should we go with the floor joists 16" on center instead of 12" on center? The reason going with 5/8" flooring is because the 12" OC floor joists. With that question is a 2"x8" floor joist over kill for this build. Could we get by with 2"x6" floor joists? Also when placing the concrete blocks on the ground should we dig down a few inches and put some class 5 or some sand under the blocks? The only lumber that will be PT is the skids that will come in the closest to the ground, but they wont be touching the ground. When people talk about staggering the joints (on a skid) are they saying if you used 3 2x8's to make a skid you would use 20footers on the two sides and two 10footers in the middle to stagger the joints. Any help would be great and I would like to give a special thanks to OwenChristensen for reading his knowelege on ideas and building pictures of what he has built. Thanks for all the help to everyone as well

stitch
Member
# Posted: 12 Feb 2013 23:10
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By the way the size of the "Shack" is 16'x20'

Just
Member
# Posted: 12 Feb 2013 23:20
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may be 2x10 x16 for the joist and rim joist same money bit stronger IMO

MtnDon
Member
# Posted: 12 Feb 2013 23:31 - Edited by: MtnDon
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Quoting: stitch
2 skids made of 3 Treated 2"x8"x20' glued and nailed.


IMO, forget the glue. Just use hot dipped galvanized nails; spiral or ring shank if you can. The nails are just to hold the three layers together so you only need them every30 inches or so, set in about 1 1/2 inches from the edges, staggered top & bottom.

Yes the beam lumber should be PT, if the bottom edge of them is closer than 12 inches to the ground. However, if the bottom edges of the floor joists are closer than 18 inches to the ground, the joists should also be PT. Ditto on the sub floor plywood.

If the subfloor does not need to be PT then see if you can find Advantech (Made by Huber Engineered Woods) in your area. It is a very high resin content variety of OSB; resists moisture better than any other wood product.

3 - 2x8 should be sufficient for beam strength when supported every 5 feet, if it is a single story. Parts of MN get 70 psf snow load and that would work to 70 psf.

If you can get 20 ft long PT 2x8's just use them. No splices at all is stronger. But if there are splices they should all be over the supports.

MtnDon
Member
# Posted: 12 Feb 2013 23:42 - Edited by: MtnDon
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Quoting: stitch
Floor Joists 12" OC 2"x8"x16'


Cantilever should be held to no more than the depth of the joist; 2x8 joist means 8" overhang or cantilever maximum. If there is a second floor no cantilever is best. High snow loads are another reason to limit the cantilever amount. All roof loads go down to the overhanging joist ends.

2x8 grade #2 of most common species used can only span a max of around 13 feet when on 12" centers. SPF (spruce-pine-fir can do 13' 6") So if the floor loads were lighter than in a typical full time residence you would still be pushing the limits using 2x8, because of the cantilever limits.

2x10 #2 SPF on 16" centers can handle 15' 5" so if you kept the joist cantilever to 10 inches that could work.

3/4 plywood, osb or advantech can handle that 16" OC span. Get the T&G type.

MtnDon
Member
# Posted: 12 Feb 2013 23:48
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Plan for a means to tie that down to the ground. Winds blow strong and the weight alone can not be counted on keeping it in place. Then there is also the uplift force along the side the wind strikes.

If you canted dig deep, well that is too bad , as you will almost certainly have frost heave movement.

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