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Small Cabin Forum / Cabin Construction / 16x24 foundation
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curt
Member
# Posted: 1 Jan 2014 23:35 - Edited by: curt
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I am planning a 16x24 off-grid hunting cabin with loft and am looking for foundation recommendations. There is no access for equipment to drill concrete piles and this is going to be located in Saskatchewan, Canada so frost is definitely a factor. The floor will be built on 3 - 3 ply 2x10 beams. I was considering digging down 8-12", 18" square holes 8' O.C. along the beams to get to solid ground without any organic material and filling the holes with crushed rock for a base. Then i was planning on using some type of blocking (steel, treated, ??, not sure yet) with adjustable screw jacks supporting the beams.
The location is remote with no road access so concrete is not an option. Looking for feedback or recommendations.
Thanks

Dekagoldwingers
Member
# Posted: 2 Jan 2014 02:34 - Edited by: Dekagoldwingers
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You should be able to get some info from the province or region about the depth of frost effect. Footings should be at or below frost line. If moving concrete in is a problem then consider making some footing pads with treated wood planks and plywood, 3 ply 2x6 24" long with treated plywood in between will give you a pad about 6" thick 24" square. Change the direction of the planks each layer. You should place this in the ground on a pad of drain gravel, as deep as possible near the frost line. If you can't dig down deep enough to place the pad, then placing rock and gravel down to frost line may work. A post of 3 2x6 treated to bring the bearing up to 1' above ground level to support your 3 ply beams should give a good support. Another option is to drive a cluster of 3 x 2" pipe down and pour a small concrete "piling cap" on the tops of pipes holding them together and providing a footing for he beam supports. The piling caps need some rebar holding the pipes together and giving strength to the piling caps. This doesn't required too much concrete, about 2 bags of premix per post.

DungeonX
Member
# Posted: 2 Jan 2014 07:30
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Search my cabin post for a couple more ideas

OwenChristensen
Member
# Posted: 2 Jan 2014 07:48 - Edited by: OwenChristensen
Reply 


If you want to dig five foot hole, you could use treated six x sixes. If you build on top the frost do not use three beams. The two outside beams will settle sooner in the spring and not the middle one. This might cause damage to your floor and cause a hump in the middle. This will always happen unless your on dry gravel or sand. Remember there isn't much weight there in the first place. Consider bigger floor joists across a span of just two beams. Digging away the humus is a good idea for the pad plan. If done right building on top the frost cause less trouble than frost posts. When I say done right, no additions, no larger, 4x8 plywood siding for stiffness, overlapping the floor sides with the plywood, stagger roof plywood. Plywood on the roof is also a good idea. The joint nails hold better. I confess though I am now using OSB because of cost.

Owen

curt
Member
# Posted: 2 Jan 2014 22:26 - Edited by: curt
Reply 


I have pretty much decided that it will be a foundation on top of the frost due to the access issues. Good point about the two beams instead of three however the NBC span tables limit me to 14'-4" span with Fir 2x10 joists @ 16" O.C. I could go to 12" spacing for the full span but it makes it much more difficult insulating the floor. I would really like to stay at 16" centers. I forgot to mention there is an 8' deck on the front with a loft over so the floor system will actually be 32' long but I should be able to use 3 ply 2x10 beams with supports at 8' O.C. Do you see any issues with moving the beams inboard 6" to accommodate the span and have the floor joist cantilever the beam slightly? My plan was to use plywood sheathing on walls and roof and 3/4" T&G for the floor. Also would there be any need to use treated lumber for floor joists since they will be raised off the ground and will not be in contact with the grade? Here is what I've got designed so far:
16x24
16x24


OwenChristensen
Member
# Posted: 3 Jan 2014 09:56 - Edited by: OwenChristensen
Reply 


Absolutely move them is up to 1'. That will really firm the floor. No treated for floor joist, they are way too weak. As long as white wood is dry and a foot off the ground it is fine. Here's a picture of a 16' x 24' like yours. Two skids on gravel pad, loft. I like your stair design. On my own 12x 20 I choose to have a closed off upper floor. It's too hard to keep the heat down.

ps. I'll delete these picture after you see them, as this is your thread.
start
start
done
done


curt
Member
# Posted: 28 Jul 2015 21:09
Reply 


Since the original concept I increased the size to 16
x 28 and added dormers to the loft. Coming along nicely. The 12/12 roof is definitely a challenge, not looking forward to installing metal roofing.
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100_1178.JPG


littlehouseontheprarie
Member
# Posted: 27 Oct 2015 22:19
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Curt looks great would love to see more pics.

curt
Member
# Posted: 28 Oct 2015 22:29
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Here is the latest.
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IMG_0125.JPG


jayinwww
Member
# Posted: 14 Nov 2015 20:38
Reply 


you have any inside pictures?

curt
Member
# Posted: 15 Nov 2015 09:33
Reply 


Still pretty much unfinished inside, insulated and stove installed. Hopefully keep progressing some over the winter and into next season.
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100_1276.JPG
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100_1277.JPG
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100_1325.JPG


curt
Member
# Posted: 30 Aug 2016 18:18
Reply 


The latest
IMG_0811.JPG
IMG_0811.JPG


AlaskaSnowbirdHomestead
Member
# Posted: 22 Jun 2017 23:44
Reply 


Sorry to bring up an old post.

I am hoping Curt is around to tell us how exactly he ended up doing the above frost foundation. I have a similar situation where I would like to build the same size cabin in the same cold weather climate, above the frost.

Hows it holding up, and how exactly did you do it Curt?

NorthRick
Member
# Posted: 23 Jun 2017 14:31
Reply 


Foundation

AlaskaSnowbirdHomestead
Member
# Posted: 25 Jun 2017 14:11
Reply 


That railroad tie cribbing looks like it would be very stable if done correctly!


I dont see why it wouldnt last a long time if it has proper drainage under it and rain was diverted away via a gutter system or large enough roof overhang. Plus you could easily replace parts of the cribbing down the road or make adjustments.

I would like to think this would be superior to concrete piers, why dont you see more people doing this?

curt
Member
# Posted: 10 Jul 2017 21:59
Reply 


I dug down to virgin undisturbed clay and placed pedestals that I built out of 6x6 treated lumber screwed together with treated plywood. These bases are very solid and were shimmed on top with the help of a laser level to support the floor beams. My place is about 5 miles away from any vehicle access other than ATV, so digging a foundation below frost was not an option. In this country piles have to be 12' deep to get below frost to avoid any movement. I have been through 2 winters and have had no noticeable movement whatsoever.

curt
Member
# Posted: 10 Jul 2017 22:04
Reply 


Here are a couple of pics of the process
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curt
Member
# Posted: 10 Jul 2017 22:09
Reply 


Progress as of this weekend....getting there!
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DSCF0294.JPG
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DSCF0291.JPG


fitzpatt
Member
# Posted: 12 Jul 2017 14:13
Reply 


Curt, love the stairs and storage room. Can you provide dimensions for them? I have been looking for various options to get up to our loft and really like your design. I have been debating something similar and was considering putting the wood stove in that area on the right of the stairs in front of the storage room.

cbright
Member
# Posted: 13 Jul 2017 14:42 - Edited by: cbright
Reply 


If I was making (and might be, so I've do some research) a 16' wide x X long building, then I would only use 2 beams (triple 2x10s) and space 13' apart. With the 4.5" per beam x 2, that give (16' - (13' + 9")) / 2 = 13.5" of cantilever .... which is basically nothing. Could even make the span a little less and increase the cantilever.

This makes it super simple to re-level the building if things get out of wack.

P.S. Oops! Didn't realize this was an old post and you basically ended up doing what I suggested.

How solid did the floor turn out to be?

curt
Member
# Posted: 14 Jul 2017 16:53
Reply 


The cabin ended up being 16 x 28 and the floor is very solid.

madge
Member
# Posted: 29 Aug 2017 13:07
Reply 


Hey everyone, just signed up.
Started a similar project this spring in Northern Ontario. Original was 16x24 but of course the misses won the battle and we ended up on 16 x 28.

milfordchief
Member
# Posted: 12 Jun 2018 16:10
Reply 


New to the forum......placing my foundation posts this weekend. Go with 3 beams or 2? Still holding strong Curt? I'm doing 16x24

ICC
Member
# Posted: 12 Jun 2018 17:17
Reply 


For most 16 foot wide cabins you do not need a central beam. If or when the foundation piers go out of level it makes for less work if you only have piers down each side and not hidden underneath.

How many piers, what spacing or have you figured that out yet? All that depends on soil and how much cabin (weight) the foundation will need to support.

curt
Member
# Posted: 12 Jun 2018 17:43
Reply 


Absolutely only go 2 if you have a floating foundation (i.e. no piles below frost). If you go with 3 you will have differential movement and you are risking floor heaving. I have been through 3 winters with no movement to speak of.

curt
Member
# Posted: 12 Jun 2018 17:52
Reply 


Winter pic
Winter
Winter


curt
Member
# Posted: 12 Jun 2018 17:55
Reply 


Summer pic
Summer
Summer


ICC
Member
# Posted: 12 Jun 2018 23:44
Reply 


Quoting: curt
if you have a floating foundation (i.e. no piles below frost)


Why would you not go below frost depth? Piers can have enough stability issues without sending trouble an invitation.

curt
Member
# Posted: 12 Jun 2018 23:59
Reply 


Sometimes you don't have a choice. I am 5 miles from where you can get a vehicle other than an ATV or snowmobile. No heavy equipment here.

toyota_mdt_tech
Member
# Posted: 15 Jun 2018 20:04
Reply 


Quoting: ICC
Why would you not go below frost depth? Piers can have enough stability issues without sending trouble an invitation.


He said 12 feet deep to get below front. I was watching a show on TV, probably history channel and there was a hospital, I think it was in Nome AK and they used piers to support the hospital and each pier was refrigerated/cooled to keep the heat from the building from being absorbed into the pier down to the permafrost thawing the permafrost out. I think the cribbing would probably help to dissipate heat, so if he is on permafrost, me may be good for many years.

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