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montecristo
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# Posted: 23 Sep 2026 05:20pm - Edited by: montecristo
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Been a while since I have been in here. My project got put on hold for a while, but I am starting my build next spring as soon as the ground thaws.
I will be building 16x32 cabin. Open space with loft.
My property is basically a woodland swamp. There is only standing water in the spring and after unusually heavy rainfall. When there is standing water, its 6" above ground at most. The soil however, doesn't drain well and (according to my neighbor) isn't stable, good soil until around 10-15ft down. Due to this and a couple other concerns, I need to go with a floating foundation.
At first I was thinking about just using simple skids, but that would make it hard to keep level from year to year.
So I am thinking about using deck blocks, with a short 4x4 wood post to a jack post (that I can use for yearly adjustments) to the underside of the beams/skids.
Looking for any comments, concerns with this approach or alternative suggestions.
Deck block (this or similar): https://www.homedepot.com/p/CAMO-2-2-lb-Deck-Block-for-Joist-and-Post-Foundation-0420 001/319396055?MERCH=REC-_-fbt_test-_-335986187-_-3-_-n/a-_-n/a-_-n/a-_-n/a-_-n/a
Jack post (this or similar): https://www.homedepot.com/p/SKYSHALO-Screw-Jack-Post-4-in-x-4-in-13-2-in-18-7-in-Heig ht-Range-24700-lbs-Max-Load-Capacity-Adjustable-Shore-Jack-Posts-DBZCQJD1G2476AGANV0- 250421/335986187?g_store=2840&source=shoppingads&locale=en-US&fp=ggl
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spencerin
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# Posted: 23 Sep 2026 06:47pm - Edited by: spencerin
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Would the jack post fit into the deck block? And it says the deck blocks capacity is 1,800 lbs.. How far apart will these deck blocks be spaced? 1,800 lbs. per block would make me nervous. I'd use a 16" by 8" x 4" solid concrete block as a footer instead. Otherwise as long as the 4 x 4 coming out of the jack post is short enough, I feel this would work. If a swampy site, I'd also inquire about the paint on the jack post. It seems thick enough to ward off corrosion, but you never know, it could be crappy paint.
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gcrank1
Moderator
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# Posted: 23 Sep 2026 09:27pm
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Coat all with tar?
To me calling this a 'floating foundation' is to an extreme, I dont get a sense of foundation at all and the weight of that structure is going to be massive.
Any chance you could float in a salvage barge to build on?
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montecristo
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# Posted: 24 Sep 2026 09:58am
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Quoting: spencerin Would the jack post fit into the deck block?
Everything I have found says not to put the jack post directly into the deck block which is why I would have a small ~1' 4x4 post instead.
Quoting: spencerin And it says the deck blocks capacity is 1,800 lbs.. How far apart will these deck blocks be spaced? 1,800 lbs. per block would make me nervous. I'd use a 16" by 8" x 4" solid concrete block as a footer instead.
I am going go with 3 beams, 7' apart. Min of 5 deck blocks for each beam. 15 deck blocks at 1800lbs = 27,000 lbs
I am however going to go with these instead. I can't find a weight rating on them but it must be similar.
https://www.menards.com/main/building-materials/concrete-cement-masonry/construction- concrete-blocks/4x4-6x6-deck-block/1794278/p-1502778698449-c-5647.htm
I am trying to find galvanized jack posts but the ones I found seem pricey. Probably will just go with the painted ones and touch up the paint or replace as needed.
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Brettny
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# Posted: 24 Sep 2026 11:51am
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I wouldnt try to over engineer this since its basicly swamp land. Your going to have to jack and re level every year or two. Your not going to be able to just turn the screw and level the place. Personally I would use the cheapest widest foot print I could buy or build. I wouldnt be afraid of useing wood blocks on say 2x2ft concrete pads.
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montecristo
Member
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# Posted: 24 Sep 2026 12:27pm - Edited by: montecristo
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Quoting: Brettny I wouldnt try to over engineer this since its basicly swamp land. Your going to have to jack and re level every year or two. Your not going to be able to just turn the screw and level the place. Personally I would use the cheapest widest foot print I could buy or build. I wouldnt be afraid of useing wood blocks on say 2x2ft concrete pads.
You're right. I am just making this over-complicated. With what I had said before, I would potentially have (15) jack to try and screw to level. It would never be easy.
Maybe I should just go back to what I was originally thinking with skids over pad footings like shown in the attached. It won't be any more or less difficult to re-level every few years.
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toyota_mdt_tech
Member
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# Posted: 24 Sep 2026 01:43pm
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Wait till dry and bring in a pile driver, drive pilings down to good solid base.
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rpe
Member
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# Posted: 24 Sep 2026 02:22pm
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Have you considered helical screw piles? This would be an ideal use case if you have good sub-surface soil and not too many boulders.
https://www.technometalpost.com/en-CA/helical-piles/
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Brettny
Member
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# Posted: 24 Sep 2026 03:38pm
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The cost of screw piles could double the whole budget.
A strong skid made from tripple 2x12 would be a bit easier to level than a thinner skid.
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