Simple Foundations

by Andy Sheldon

in Building

A few years ago my wife and I were fortunate enough to attend a wedding for a daughter of a friend of ours in the Adirondacks. The event was held on their family property on Lake George… several houses, a boathouse and another small building containing the laundry and workshop.

On thing you may not know about Architects is that we cannot see  building without poking around a bit, looking at the details, structure, design and construction.  And of all the buildings on the property, this was the one that caught my fancy the most.

It was a nicely detailed building but unpainted building. Although the wood had weathered nicely, you wondered why it had been left unpainted, while all the other buildings were painted white.  But it was a wonderful combination of being elegant and rustic at the same time.

But the thing that caught my eye the most was the foundation… just several piles of stones.  Not stone piers with the round Adirondack stones with mortar, but literally piles of dry laid flat field stones. And these stones were only about 6″ below grade… not anything close to being below frost.  This is surprising, considering the area freezes every winter and the ground experiences frost heaves.

I began to wonder why this building that is about 100 years old had survived the ravages of winter for so long. After some pondering, I believe I know why:

  • The building does rise and fall with the frost.
  • The reason it was never painted, was probably that with the its movement the wood could never hold paint,
  • Since the piles of stones had no mortar and acted like a dry laid stone wall, they were well drained so were not subjected to ice damage.
  • It was obvious that the stones were constantly maintained by the various kinds of other pieces of brick, steel shims, etc. used to keep everythign in place.
  • This was a summer utility building, and was “unimportant” compared to the more grand other buildings.
  • It was a small building with no need for support except at the perimeter where the stones could be maintained easily.

This whole experience got me to thinking about how simple this foundation was and how applicable it might be for a DIY builder and a small cabin or tiny house in a remote location.

I would not normally suggest that a foundation be above the frost line, but if the cabin is small enough, it would act almost like single structure and rise and fall with the frost primarily as one unit.  In fact, the qualities that allow a tiny house to be mobile would allow it to move with the frost.

I would love to hear from anyone about their thoughts on simple foundations for DIY builders.
As always, your comments are very valuable not only to me but to the others who drop by.

Best,

Andy

Leave a Comment

{ 10 comments… read them below or add one }

David Lamothe December 23, 2013 at 4:49 pm

Some foundations that might be considered are a rubble trench foundation (Frank Lloyd Wright’s solution), a berm foundation (railway track foundation) and finally a FPSF foundation (Frost Protected Shallow Foundation).

All three are fairly low tech and offer advantages compared to traditional foundation types as well as disadvantages.

A high tech solution would be Steel Helical Screw Posts.

One question, what type of soil is the structure your describing, if well drained frost may not be a problem. Farm where I grew up all the out buildings were sitting on that type of foundation. Soil was loam over blue clay, but frost heaving did not seam to be aproblem

Reply

Andy Sheldon December 23, 2013 at 8:43 pm

The soil was shale and clay, and the building did rise and fall a bit with the frost.

Reply

Charles (Chuck) Rosen August 13, 2012 at 3:54 pm

We live about 30 miles from the Texas/Galveston coastline. Our soil mainly “Gumbo” – a thick, black, mud when wet, and just hard when dry. We have a 10 x 15 storage building in the back yard that has withstood many hurricanes during it’s lifetime, of which I am familiar with only 7 years. It has two skids made of two 6 x 6 treated timbers resting on 12 x 12 concrete pads. It is level and sturdy, with no signs of decay. We do have a very good lawn which is green, and the top soil it grows in is several inches thick.

For ease of construction, I think that this is one of the best. The roof is standard roofing material, and the walls are standard clap board, studs, and tar-paper.

If the main beams did not have the concrete beds to rest on, I do think that they would have rotted away many years ago as we do receive a good bit of rain each year.

This construction seems to be a very sturdy method. The things to remember is to have two to four inch thick 12 x 12 pads to support the main beams. This gets the beams off the earth so that they can shed water and reduce the chance of rot. The pads also reduce the sinking of the shed as they distribute the weight of the shed over a larger area than without the pads. Use several pads for each beam to reduce bowing.

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Andy Sheldon August 15, 2012 at 2:24 pm

Thanks Chuck… What you describe is a very solid foundation system. Many people miss the value of spreading the load over a larger area as you describe with the concrete pads. Another good practice is to set the pads on a layer of compacted gravel. This helps prevent frost heaving by keeping things well drained.

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Kay Dayss March 11, 2012 at 3:18 am

My tiny house (officially a shed) was built by a neighbor using a book and my design. It has five tall skinny windows in each 12′ side and two skinny windows on either side of the door in front. I called it my tea house until I filled it with junk and called it my shed. It is 8′ by 12′ and sits on top of four flat cement blocks (about 10″ square and 3″ high) that are right on top of the ground. Our frost line is 12″ down but usually the ground isn’t frozen for very long. To level the building, they (my neighbor and his daughters) just dug down an inch or so for some of the blocks until they were level. I never thought about it not having a foundation because I didn’t know about “heaving” 8-) Anyway, it is a very sturdy little building. My neighbor said that it is so strong that I could easily just move it to a new location if I wanted to move. I painted it green, so I sometimes call it my green house. When I get the junk out of there, I might just paint it inside too instead of finishing it — from another of Andy’s ideas. Or my sister suggested that instead of using sheetrock, I should just use 1-by lumber to finish it so that I can insulate it. Then I’m going to get a direct vent stove and use little propane bottles to heat it since I cannot tolerate wood smoke. The back will have a tiny bathroom and a murphy bed. I found a tiny fridge microwave combo and a two-burner stove. I’ll put in a counter and sink along one wall that will double as a desk and eating area. The other wall will have a comfy leather easy chair that can pull out into a little bed if needed. The loft area above the bathroom will be for storage. It can be a shelter in a pinch if I have to rent out my house and move into the shed to survive. 8-)

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Andy Sheldon March 11, 2012 at 10:27 am

Would you like to share a picture of your little shed/house? It would be nice to see what others are doing too.

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Scott March 10, 2012 at 2:01 pm

Regarding your simple foundations article, I dont see that as any different than all
the portable sheds sold at Home Depot and Lowes which are built on 4×4 or sometimes
6×6 skids and off loaded onto stacked concrete block and pavers when delivered. These sheds come up to 12 x 20 ft long and sometimes 2 story. I’d say for small structures
they are pretty rigid but I know they can twist a lot which is why all the pavers must
be perfectly level when set up for the doors to work properly.

I sent you a rough sketch floorplan layout of a super compact 4 bdrm
CapeCod house a year or two ago that I lived in as a college student . Remember?

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Andy Sheldon March 11, 2012 at 10:38 am

Yes Scott, you are right… the piles of stones are essentially the same as the concrete block approach. What surprised me in the Adirondack building, was that it was larger than shed size and had withstood so many harsh winters. I do recall the sketch you sent… thanks for reminding me.

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Tom T March 10, 2012 at 1:02 pm

Andy,
I have seen several small cabins/sheds built using packed gravel as the base for a slab or simple gravel floor. Down here in Texas we don’t have the freezing weather of up north so it is not that much of an issue. We do have “black gumbo soil” which shrinks and swells with the amount of moisture in it. I guess you could say that is our “frost heave”. I could see a gravel bed used as the foundation for a remote cabin.
Respects
Tom

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Andy Sheldon March 11, 2012 at 10:42 am

The compacted gravel approach is also common with garden sheds to support the skids. Because it is well drained, it less affected by freezing. But in your case, as you say, you don’t have the cols conditions that cause problems.

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