• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education skip experiences global resources cider press projects digital market permies.com pie forums private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Carla Burke
  • John F Dean
  • Nancy Reading
  • r ranson
  • Jay Angler
  • Pearl Sutton
stewards:
  • paul wheaton
  • Leigh Tate
  • Burra Maluca
master gardeners:
  • Christopher Weeks
  • Timothy Norton
gardeners:
  • Jeremy VanGelder
  • Paul Fookes
  • Tina Wolf

Is building a foundation below frost line necessary?

 
Posts: 35
2
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
A lot of small / tiny houses use concrete deck blocks for their foundations. Is it not necessary however to build the foundation below the frost line to prevent frost heave?

 
pioneer
Posts: 176
Location: Zone 4b Ontario, Canada
45
goat medical herbs solar wood heat rocket stoves homestead
  • Likes 3
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Tiny houses on blocks may have more to do with:

1)  Ability to pick up and transport, considered non permanent structure and therefor cost less in Municipal land tax, and require fewer permits.
     Because they sit on blocks on the ground there is little in the way of frost heave that would damage the structure.

2)  Buildings on foundations are considered "immobile" and Municipal by-laws require building permits, and land tax is greater.

Cheers!  K
 
pollinator
Posts: 4488
Location: Canadian Prairies - Zone 3b
1221
  • Likes 1
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
From what I've seen, I think it has a lot to do with how the tiny house is constructed. Like many sheds, they are designed to be mobile and to be moved. So, they are constructed on a trailer frame or built on a very sturdy and aggressively cross-braced timber frame. As a result, they don't really sag and deform.

If the tiny house is permanent and depends on the foundation for its structural strength, though, it is wise to go deep with the pilings. Otherwise, cracks and ill-fitting windows and doors, and even water incursion will make you miserable. Screw pilings, which you can generally install yourself, have a threaded "jack" section at the top that lets you adjust the height in case of unexpected movement. They work great for decks; I think they would be excellent for tiny houses as well. My 2c.
 
master steward
Posts: 6517
Location: southern Illinois, USA
2295
goat cat dog chicken composting toilet food preservation pig bee solar wood heat homestead
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
In northern MN, I have seen people float barns on top of the soil.  The one I have followed up on was built about 1978 and is still standing.   It measures around 40 x 60 ft.  I have also seen houses over 100 years old built in same way. In all cases the foundations were railroad ties or similar. In all cases the soil had a high amt of sand.  Now, I would hope, we could select something other than ties.
 
pollinator
Posts: 241
61
  • Likes 1
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Agree with the need to know what type of TH being planned. Could be small and mobile enough to sit on skids or trailer; could be a TH on a foundation, requiring similar foundation types as are used in other stick-built homes.

If a permanent foundation is desired, then you have all the choices that are typical for your area, and that you or the homebuilder (and engineer?) is comfortable with designing and installing; building codes are also in play.

Having said all that, perhaps a frost protected shallow foundation (FPSF) can be utilized in your area ...

Regardless of foundation type, you can't spend enough time and money in making sure water is kept away from the foundation or pad area; raising height of pad, swaling water away from the pad, draining water with french drains to daylight, sealing/insulating, etc. Once the foundation is done, there is less opportunity and interest to go back in and fix issues.
 
pollinator
Posts: 872
Location: Thunder Bay, Ontario, Canada
172
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Up in the Canadian North (in the tundra), there are vast areas of muskeg (peat) which can be 50ft deep. The general solution is to excavate it all out and then fill the hole with crushed rock that they excavate from a nearby rocky formation called an esker.

It's extremely expensive and difficult to do (just getting the heavy equipment in is a major undertaking), and the availability of above ground rock is quickly diminishing.

Engineers are trying a lot of different alternative systems, one being where the building sits on concrete blocks, which in turn sit on Styrofoam blocks that distribute the weight over a larger surface area. The concrete blocks have a threaded rod set in them, and the building has a coupling that allows for it to be levelled periodically as the underlying foundation rises and falls.

 
A magnificient life is loaded with tough challenges. En garde tiny ad:
100th Issue of Permaculture Magazine - now FREE for a while
https://permies.com/goodies/45/pmag
reply
    Bookmark Topic Watch Topic
  • New Topic