Foundation Question

[jonw]

Hi,
Could anyone advise me on the following foundation for a 10'x12' cabin?

I would like to use two rows of three dek block piers (described below). These rows will be about 5 feet apart and the blocks in each row will be 4 feet on center.

To build the piers I will dig 6 holes (spaced as described above) and fill them with gravel. On top of each hole I will place a 16"x16" paver. On top of each paver I will place a dek block. The dek blocks will support 4"x4" posts and the post will support two girders. Each girder will be built of (2) 2"x12"x12'.

The floor built on top of the girders will be cantilevered 1' to 1.5 feet all around and tied down with cable and anchors.

My question is:
Will this work in a cold, frosty climate?
Thanks.

[Bouncer]

How bout something like this
http://tinypic.com/view.html?pic=23l6za

[glenn-k]

Hi jonw,

Here is the information John has posted on the main website front page.  One of these may work if your conditions are right.

http://countryplans.com/foundation/index.html

Aside from that , it pretty well requires a local professional such as an engineer or architect since each site, soil conditions, freeze conditions etc. vary so much.

If you are in a permit required area the building department may offer suggestions of what is acceptable, if not you may check with your neighbors and see what is used commonly in the area.

[Amanda_931]

When John and his boys built the first "little house" they buried the deck blocks about half way, from their pictures--they start here.

http://www.jshow.com/y2k/listings.html

Seriously tamped, smallish, sharp-edged gravel is apparently what you want in the hole, according to one of the local builders.

There are deck blocks and deck blocks, though.

There are two kinds for sale around here.  One just for 2x joists.  One for either an upright 4x4 or 2x going either direction.   But neither have brackets to tie your wood to the deck block.  John recommends making your own.

I'd hate to tie my house down like a mobile home.

Take a look at the idea of insulating the piers.  

See what  early houses in your area had--and if it seems to have been a point of failure.

Cold and frost may be less important than CLAY under your foundation blocks, especially expansive clay (great for sealing things, but frost heave is a byproduct there)

Apparently people go to great lengths to make the buried part of the blocks SLICK.  So frost doesn't grab and lift.  Everything from plastic bags taped around them to patent footing/deck block combination forms made of smooth plastic.

Here's one, not the one I was looking for, though.

http://www.soundfootings.com/howitworks.html

[Amanda_931]

 

This wasn't the one I was looking for either!  But it's quick and lightweight.  If it lives up to expectations.

http://www.redifooting.com/

[jonw]

Hi,

Thanks everyone for the comments, so far. I've checked out the links. They are very helpful.

I would like to avoid mixing a lot of concrete on site, as there is not a water supply yet.

No need for a permit for this size building in this area.

I have a clay/gravel soil. I was thinking that the gravel bases for the blocks would help to eliminate any trouble in this area. Also, the building is so small that my guess is the weight will be distributed easily by the piers. But, I am not an engineer and I am guessing.

In the end, if I don't find information on this foundation type, I will likely go with cement tube piers using hauled water. Or, something like the plastic piers--though it appears cheaper to make the concrete version.

How about the cantilevering of the floor over the girders. Any ideas? This would allow me to easily to skirt the cabin and insulate the perimeter.

Thanks again!
Jon

[jraabe]

Is it too obvious to suggest the Little House plans that have a 10' x 14' cabin with post and pier foundation where the joists are cantilevered over the foundation beams?

http://www.jshow.com/y2k/listings/29.html

[jonw]

Hi,
Thanks! I checked all of that out and it answers most of my questions. Only one question now:

Will it heave with the frost? My guess is it won't if most small homes prior to WWII used this system.

I haven't seen similar blocks to the ones used in the photos in my builder's supply store. But, they must be out there.

Thanks again.

Jon

[glenn-k]

That's what I get for not being familiar with the plan :-/

[Amanda_931]

(No, John, it was not too obvious to say something on the order of "look in the book!")

a) John also mentions a way of insulating the below-ground part of the piers.  It's in the plans!  I think it's even described in detail on the plans home page.

b) If you skirt and insulate your perimeter that might work just about as well.   Although a layer of insulation might be good insurance.

Fine homebuilding had the ultra slick pier footings in the questions part of a recent issue--maybe even the latest.