Building Code Hacks: Foundation in Cold Climates
This series is created to educate home owners regarding the items regulated by the Building Code**, so that they are informed enough to know if something is being done wrong during the construction process. DIYers out there and contractors/ builders are also welcomed. We all need to remind ourselves of the "code sings".... (sigh) once in a while .
PROTECTION FROM FREEZING (OBC 9.12.1.3.)
If you are constructing during late fall-winter months, you have to make sure to protect the bottom of the excavated area and poured footing from freezing at all times. The reason for doing that is to prevent soil frost heave ruining your foundation and undisturbed soil. Soil frost heave is technically water freezing and subsequently expanding and moving the objects around. This is a link to a good video on Foundation Frost Heaving, check it out if you want an illustration on how frost heaving can damage your foundation. Insulated tarps or insulated poly blankets are usually used for protection.
MINIMUM DEPTH OF FOUNDATIONS (OBC 9.12.2.2.)
There are also regulations regarding the minimum depth of your foundation walls. It all depends on the type of soil, soil drainage and whether your basement is heated or not. There are no limits for the heated basement when the soil is stable, but there is a minimum of 1.2 m foundation height for clay or soils not clearly defined. There are more restrictions for unheated basement when it comes to the min height. In most cases foundation has to extend to the frost penetration line. Please note that regardless of the site conditions and building type, the excavation of the soil for the foundation should extend to the undisturbed soil.
If your foundations is insulated in a way that it reduces the heat flow to the soil, you should comply with the section of the table related to the Unheated Space.
EXCEPTIONS TO THE RULE (OBC 9.12.2.2.)
You don't have to comply with the requirements for the minimum foundation depth if you are constructing a building:
that is not a masonry building or contains masonry veneer;
accessory building complying with section 9.12.2.2.(6);
decks and other exterior platforms;
exterior concrete steps that have not more than 2 risers;
These are not the only regulations regarding the foundation outlined in the building code, there are also sections regarding the dampproofing, waterproofing, protection from soil gases, etc. More to come about those topics later. Hope you found it useful.
**This article is referencing Ontario Building Code