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Mushroom Man
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# Posted: 8 Jun 2017 05:42pm
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I need some advise. I'm starting my 12-24 tiny house saturday and was planing on pouring concrete into tubs (10" tubs) that will be 26" below ground / 12" above...total of 12. Needless to say that is going to be a lot of work.
Would it be better/easier/cheaper to use 6" deep of rocks and place concrete deck blocks down instead?
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rockies
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# Posted: 8 Jun 2017 07:41pm
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What is the depth of frost in the area? 24" deep is not a lot (it won't provide much lateral stability).
Is this going to be a shack or a cottage? If it's just a summer shack for camping you might as well put down concrete pads and lay some pressure treated timbers on top of them and then build the floor platform on top of those.
If this is going to be a home to live in all year and you want to hand it down in 40 years then put tubes in to a depth of 4-5' (use those Bigfoot tubes with the flared base that creates it's own footing at the bottom of the tube).
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toyota_mdt_tech
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# Posted: 8 Jun 2017 07:57pm
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If you do the pillars, I'd dig below frost line, put a footer down first, then a concrete sono-tube up to cabins floor level. This is one area you want done right and done once. Its hard to go back later, its hard to level it later, its hard to repair it later. A foundation is one of the most important parts of a structure IMHO. I just did a dig out and did the full footing/stemwall, it was so much less labor and I left out the crawlspace access from outside, its inside and it gives me a bunch more secure storage to boot.
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Mushroom Man
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# Posted: 8 Jun 2017 08:45pm - Edited by: Mushroom Man
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See attached pic.
It is going to be my retirement homestead so yes....I want it to last for many years. The frost depth is 22 in. So I'll dig down 22" + 6"...correct? How many inches of rock do I pour down the hole first? Does this count toward the total depth of 28"?
My plan is to dig 10" holes (I have an auger) and place my 10" tube into it and start filling with concrete. However...that is a lot of concrete! I don't have experience in this but I have a good understanding (youtube) how to do it and do it right. However...I am confused regarding IF I need to put rocks at the bottom.
Also, the flared base, would cause me to widen hole and I would have to do that by hand because my auger is only 10" wide.
So what is the best way, least expensive and low labor? I do want to do it right but I have to completely do it on my own and I am turning 50 this year. lol.
PS...Don't pay too much mind to the smaller footing. I'm adjusting the size of the footing to 10" (12" is a little much...I think). You let me know if it is a good size please.
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rockies
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# Posted: 8 Jun 2017 09:00pm
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That's a lot of footings along the length of the cabin (six?)
You should be able to get by with 3 (what size is your perimeter beam?)
I would go down 36" for your footing tube just to be safe.
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Mushroom Man
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# Posted: 8 Jun 2017 09:06pm
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Perimeter is only 12'. I'm going to have 2 - 55 gl. drums in the loft on the right side. I thought I might need the extra footings for the weight. I could drop it down to 4...3 + one extra on the right side for added support?
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creeky
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# Posted: 8 Jun 2017 09:08pm
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For a small cabin your size. Take a careful look at the posts and builds of Owen Christensen. You can find them in search.
He is, by far, the best source of info on building small cabins. And not just on this site.
Two things I might add. I like the new screw pile foundations. I've built one. Badly. Took me less than an afternoon and it has worked perfectly fine for two years. No worries about frost heave.
The second. Owen was a big fan of a bed of rock for drainage; with concrete blocks on top. He said that a small building was easily lifted for adjustment due to frost heave. If required.
But you'll find all that out. Good luck.
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rockies
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# Posted: 8 Jun 2017 09:13pm - Edited by: rockies
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Well, if you're going to have drums like that on one side (up in a loft) then one more pair of footings on one end (mid-span between the center pier and the end pier) wouldn't hurt. Just place the extra piers under the point where the loft support studs come down (the "Point load").
Also, mixing your own concrete can be "FRAUGHT WITH PERIL"!
Don't wind up with weak concrete.
https://www.familyhandyman.com/masonry/pouring-concrete/how-to-properly-mix-concrete/ view-all
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Mushroom Man
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# Posted: 8 Jun 2017 09:13pm
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That's what I was thinking creeky! I would much rather go that way then the concrete footings. I'm just concerned about how long it would last.
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Mushroom Man
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# Posted: 8 Jun 2017 09:23pm
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Well. I'm thinking that I will place concrete blocks on about 16-12" of rocks for drainage. I'll move the 2x6 about 12" from the edge of the walls so to keep the weather/rain for getting to them.
The house is only 12x24'. I've seen large cabins done this way and still looking strong after 40 years.
Thoughts?
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ICC
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# Posted: 8 Jun 2017 10:02pm
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Depends how lucky you are. I built a cabin on Dad's ranch in '66. I did it my way. On big rocks. Then I was in the service and was away from the ranch for a few years and when I returned the cabin was out of kilter. Door was hard to open, one window was stuch and a ball always ended up under the stove wheb dropped on the floor. Over a few year period I adjusted it twice, then gave up. Built a new place to live in like Dad said I should have in the first place and like the Navy showed me to do too. That second cabin is still used for seasonal ranch work and is level, doors & windows work.
Since that first build I have seen a lot and built several things from barns and sheds to my 10 year old two level home. All have regular foundations except for a couple storage sheds. Those are on blocks and one is a SOB to keep the doors from binding.
I have never understood the penchant for putting rocks or gravel under piers for drainage. Drainage works both ways, in and out. Just because you want water to drain away doesn't mean it will. Depending on circumstances there is a good chance water will fill the empty spaces between the rock, maybe slowly drain away, maybe not. The IRC states it is correct to place a footing on bare dirt, no gravel wanted. And if some fill is needed it must be tamped to correct firmness. Digging down and pouring a footer on bare virgin ground is approved and simple. Your footings also generally need to be bigger than the pier end. 16 x 16inches is usually code minimum IF code lets you use a pier.
Toyota-guy is right that a full perimeter footing, stem wall and crawl space being a good way to go. You do it once the right way or you keep kicking yourself when something goes awry. Sure it takes more effort, more money, but it's once, not over and over. The do overs get harder as you get older too.
Some are lucky and have few problems but IMO it is those who guess a lot and take short cuts who end up with more problems.
Best o' luck
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Mushroom Man
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# Posted: 9 Jun 2017 08:39am
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Thank you ICC that is the push I needed. I have a 5 yr plan to have the property ready for retirement. So I don't have to go out there and do it all at once.
Also I'll be changing my footing to 8 instead of 12.
Looking for the material I need now and will head out this afternoon. I'm filming everything for a youtube channel so I'll keep you posted.
Thank you everyone!
Mushroom Man
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toyota_mdt_tech
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# Posted: 9 Jun 2017 10:26am - Edited by: toyota_mdt_tech
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M/M, is there acces to get in a tractor and cement trucks? If so, the full footer/stemwall is actually much less labor.
I did it because it was so much easier. I did hire out the foundation after the site was prepped, ie he did the forms, rebar, called in inspector, then called in concrete. I showed up to build, I have a nice footing stemwall in place. It cost me about $3800 for it all. Good value IMHO, never a single critter has gotten inside of it yet. It will still be in place and level, long after I have assumed room temp.
I showed up to my place with lumber pkg in place and foundation all done. It was a breeze. If you do go this route, I would backfill the foundation before starting too to final grade. Mine wasnt and it made everythign in the front real tall.
My concrete guy did install a 4" drain tile under the footer at the lowest end, so if water ever did end up in there, maybe form a pipe burst or whatever, it would all drain out easily. My area is so dry, there is zero moisture and its graded and sloped right, lots of gravel under the cabin and a nice black vapor barrier.
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NorthRick
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# Posted: 9 Jun 2017 01:48pm
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Quoting: Mushroom Man So what is the best way, least expensive and low labor?
At work we have a saying, "There's fast, cheap, and good. You can have any two but never all three."
As others have posted, don't skimp on the foundation.
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rockies
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# Posted: 9 Jun 2017 06:50pm
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Crawl spaces can also be FRAUGHT WITH PERIL! The materials and construction methods can be top-notch but the problem is usually venting/moisture issues.
http://www.greenbuildingadvisor.com/blogs/dept/musings/building-unvented-crawl-space
http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/upgrading-crawl-space
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ICC
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# Posted: 9 Jun 2017 07:45pm
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Like everything, do a crawl space wrong and it's hell, do it right and life is wonderful. Research such linked to is invaluable. Maybe spend the weekend researching & planning before jumping in without knowing what the next steps are?
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