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Osceola
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# Posted: 4 Apr 2017 08:18am - Edited by: Osceola
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I've read quite a bit on this site and others and there doesn't seem to be a clear consensus on the best foundation for a small cabin. The low cost and ease of installation of post & beam, pier & post or skids/runners (I can't even get the terminology straight) is appealing to me, but I have misgivings about building a cabin on a foundation that may be problematic down the road, just to save money. You know, penny wise, pound foolish...
With that said, we are building a 14 x 24 cabin on our Michigan property and the excavator I'm hiring to do the site prep has recommended a professionally installed block crawl space. What do you think about his recommendation versus the cheaper alternatives? My site has sandy loam soil and a slight slope. We don't intend to ever install plumbing. Electrical wiring and propane lines only. Thanks in advance for your opinions.
P.S. The building inspector requires footings below the frost line.
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toyota_mdt_tech
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# Posted: 4 Apr 2017 08:58am - Edited by: toyota_mdt_tech
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I used the full footing/stemwall, and on a single pour, kept my crawlspace door in the floor for more secure storage. That is the best option. If you can get the equipment in there ie excavator, you can get the cement truck in there. It was the fastest, least labor intensive and the best foundation. Cost for more concrete and rebar is all. I have zero regrets, the fact, I never have varmints in my insulation is a huge plus too.
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Kamn
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# Posted: 4 Apr 2017 09:11am
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We haven't built our cabin yet but we are going for something along the lines of 20x30 and foundation will be block wall and footings below frost line. I don't want to have to deal with leaning piers or problems like that, as Toyota_mdt_tech mentioned, no varmints, safe place to store, and this is where we can also have a cold cellar for food storage as well as where the water filters, pump, pressure tank can all stay........as well as all the batteries for our solar setup
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bldginsp
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# Posted: 4 Apr 2017 08:31pm
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A block foundation, correctly done with rebar and grout, is for all practical purposes as good as a solid poured-in-place foundation, and costs a bit less to do.
A full perimeter footing below frost line is the best chance you have for a stable, long lasting foundation. Sandy loam soil is one of the worst soils for building purposes, and probably one of the most common. Making the bottom footing extra wide gives it more bearing area and that much more insurance.
How long do you want the building to last? Any building built on posts stuck in the ground or concrete piers alone is not going to last family generations, or it will require very difficult repair at some point. Here are the two options:
"Well, you know, Grampa didn't really do the best job on the cabin, it was great when we were kids, but the floor is uneven now and the doors don't close"
Or
"Hey you know Grampas cabin is still in decent condition- if we just put a new roof on it and spruce up the kitchen it'll be good for years"
Some people just want a temporary cabin, fine, if that's what they want. Me, I don't want to be faced with major repairs 20-30 years later. To each his own.
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Osceola
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# Posted: 5 Apr 2017 08:00am
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Thank you for the feedback. My bias is toward spending the extra money now if it means it will last, but I guess I'm just looking for confirmation before I make that investment. I'm disappointed to hear sandy loam is not ideal.
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Osceola
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# Posted: 5 Apr 2017 08:02am - Edited by: Osceola
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"kept my crawlspace door in the floor for more secure storage."
I like your idea of access from inside rather than out. Thanks for the tip.
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OwenChristensen
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# Posted: 5 Apr 2017 08:48am
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All or any type of foundation can be problematic. In good drainage a foundation like your planning can be fine, but in wet conditions right before the winter freeze up, it can be pushed in. A basement foundation on a home only lasts in the north if heated. Concrete pales compared to frost expansion.
That being said, frost posts too can have lift if water isn't kept away as the ground freezes.
Gravel higher than the surounding top soil, drainage trenches with drain tile, and just landscaping to divert rain runoff is most important.
The absolute best foundation I have seen is a trenched in footing with rerod re-enforced posts extended up to the cabin beam level and back filled.
Owen
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bldginsp
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# Posted: 5 Apr 2017 09:09am
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Quoting: Osceola I'm disappointed to hear sandy loam is not ideal.
It's not ideal but it can be dealt with. Most houses in the US are built on less than ideal soils, because we like to build on flat land which is usually all the stuff that washed down from above over the years.
My grandfather built a cabin with a minimum of piers on bedrock, its just fine today. Few people have access to bedrock on their land.
A pier foundation in sandy/loamy soil will eventually suffer problems because each of the piers, or some, will move in relation to the others, messing up the floor, walls, roof of the cabin. A perimeter foundation is a single unit so it's much harder for part of it to move in relation to the other parts.
Here's a link to a soil bearing capacity chart and basic explanation:
https://www.concretenetwork.com/concrete/footing_fundamentals/why_soils_matter.htm
The other thing about a perimeter foundation is just its size. It puts 10 times or more the surface area on the soil for a building to sit on compared to piers. When you do the calculations, usually even a 1 foot wide footing is way over the weight bearing capacity of mediocre soils.
With rebar in the foundation to make it rigid and keep it from breaking apart, you have a very solid base.
I have seen perimeter foundations sink into the earth enough to require repair, but that's very, very rare with a spread footing, and usually occurs in the very worst scenario, which is deep topsoil full of humus. For a cabin, a spread footing is almost overkill, but the problem is that the alternatives are extreme underkill. There's no half way.
My cabin is built on a 300 ft deep layer of silty clay, about the worst possible. I know its that deep cause I drilled a well.... but anyway I put in a 16" wide full spread footing with lots of rebar and I have no fears at all.
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gauman2
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# Posted: 5 Apr 2017 12:28pm
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If you ever plan on selling down the road your potential buyers will have an easier time financing with a foundation over piers. I have piers and no bank would take on the loan. In my opinion do it right the first time.
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1tentman
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# Posted: 5 Apr 2017 01:45pm
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I would agree that a full concrete foundation and footing would be the best way to go, is this a diy project or will you hire it done. Alot of people get scared when you mention concrete and forms but it really isnt that hard to do on a small pour and a short foundation wall.
There is one system that i havent ever heard mentioned on this forum,and that is building with ICE blocks.The price might be alittle higher , but it makes the job alot easier for a diy builder.
This system has a couple of advantages - no cement forms are needed the blocks are the forms, and when done both the inner and outer surfaces are insulated. There will be a full 6 in. concrete wall depending on the blocks you buy. We have alot of buildings built in our area using this system. Might be worth your time to google and check it out.
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Jon G
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# Posted: 6 Apr 2017 07:39am - Edited by: Jon G
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My proposed cabin build is located on a flat lot with sandy soil, I have access to new pressure treated wood pile cut offs. They are like poles but twice the size and around 4ft in length.
It was my plan to use this as a foundation as concrete is out of my budget.
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Osceola
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# Posted: 6 Apr 2017 09:35am
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gauman2, good point. I don't plan to ever sell, but things change. It's still a good consideration.
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Osceola
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# Posted: 6 Apr 2017 09:41am
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1tentman - I will be building the cabin with the help of an experienced framer (nephew), but I'm not comfortable doing a full perimeter foundation myself. Time is a consideration as well. Of course, that will add substantially to the cost versus diy with skids.
I haven't gotten any estimates yet. What do you think a full perimeter 14 x 24 block wall crawl space will cost me? I'm trying to avoid sticker shock...
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1tentman
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# Posted: 6 Apr 2017 01:36pm - Edited by: 1tentman
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Osceola I dont have any estimates on the cost. I need to clarify one thing, I referred to the blocks as ice blocks thats what we call them around here. The correct name is ICF blocks and they are available in 4,6,8&10 in.wall thicknesses.If your nephew is a experienced carpenter I think you would not have a problem building your foundation with this system.I have noticed that alot of people talk about concrete block foundations on a footing. The only thing I see good about that plan is the footing, I would stay away from blocks for a foundation I have seen to many failures, but that is just my opinion. If you form it up or use the icf system make it out of solid concrete you wont be sorry later. Take a chance Columbus did.
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Kamn
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# Posted: 6 Apr 2017 01:50pm
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nothing wrong with block wall foundation, only wrong installs by people who don't know what they are doing
My house was built in 1930 with a block wall on footings that is still standing strong today
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rockies
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# Posted: 6 Apr 2017 07:15pm
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The first question to be asked is: Can you get a concrete truck in there? Then it's: Do you plan on using the foundation area for utilities, storage, living space?
If not, then going to piers makes sense from the standpoint of not needing lots of concrete, formwork, rebar, excavating, etc (plus waterproofing, insulating, venting and back-filling). Badly vented crawlspace foundations can become so humid that they're really more suited for growing mushrooms.
Piers do have problems with frost heave and lateral stability. There's nothing really keeping it plumb other than the connection to the floor support beam.
I was considering piers (metal screw piles) for my foundation until I discovered multi-point space frame foundations. They are used in the arctic because of the permafrost conditions. They don't need excavating and remain completely stable, even on soft soils.
http://multipoint-foundations.com/
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