Slab on Grade in QC

Found my first slab in 500 inspections today. House is 30 yrs old, no movement/ heave or problems noted. But slabs up here need stem walls to footings below frost line to prevent heave (apart from new fangled insulated types i’ve read up on) So what do i write up?? "Dig down where accessible to determine if proper depth stem wall is installed… blah blah ??

I do only Visual inspections .

Write Foundation not visible…
No evidence of movement.
I would move on and do rest of inspection .
If you have any concerns then write further evaluation by qualified person.

Good advice Roy.
And just for chits and giggles, This was my first home in 1972 built on a slab in Northern Maine equivalent to QC weather.
Never moved. Enough heat loss through the concrete and was known back then as a floating slab. Plus it was partially on ledge.


Thks for advice boys…

Just that the client was very skeptical,
He understood slab meant no foundation…
and it is hard to convince him a slab was a foundation
and acceptable… but not used in this climate!!!
So why is this one acceptable, he asks !!!

writing “not visible” is easy, explaining is kinda difficult

Forgive my ignorance but what is a stem wall?

Probably not too many in your area Vern, nor mine. :slight_smile:

Per Bob Villa;
A stem wall is typically three courses high. Every set number of inches—which varies depending on code and the height of the wall—the cell or block is fitted with number five steel rebar to reinforce it once the concrete is poured. Once the three-course wall is in place, dirt is backfilled against the stem wall and compacted. This pad will be the base for the [FONT=Trebuchet MS]concrete[/FONT]


Stem walls are supporting structures that are utilized as a means of joining the foundation of a building with the vertical walls constructed on the foundation. The wall is often constructed with the use of concrete and steel, and works with the foundational slab to create a solid basis for the building. Along with establishing foundational integrity for the building, the stem wall also aids in minimizing damage to the materials used to create the vertical walls.

Thanks Marcel
Your right I have not seem anything like you describe. All foundations here have to be below the frost line 4’-6" or a grade beam on 12" dia X12’ deep piles.

HI all,

New here, so bear with me as I get my “footing.” :slight_smile:

The Ontario Building Code, and most throughout Canada require footings that go below the frost level so foundations don’t heave. In Ontario, it’s 4’.

However, it’s becoming more common in some single storey buildings that a “club” footing is used in lieu. Basically, if you get an engineer to stamp the design, you can pour a club footing in lieu of digging down 4’ and pouring a strip footing, foundation wall, backfilling, etc. It is very cost beneficial in most cases, and will also give the same protection as long as properly insulated where required. Essentially, it is a slab thickening along the perimeter of the slab on grade. The cost of a Professional Engineer to design it is easily offset with all the additional excavations/backfilling, and concrete supply/formwork.

From what I hear, this footing has been used and is accepted by codes in Scandanavia for years…but codes here still require an engineer to design/stamp one although they are well proven!!

One of the contractor’s I served/advised for R2000 purposes in 1987-9 built 57 townhouses/duplexes in a project called “The Village” using this form of slab-on-grade foundation. He used a plywood/foam sandwich as the forms for the edges. There also was a 2’ wide foamboard insulation skirt with a slight downward angle out from the foundation edge.

The plywood “forms” were left in place and backfilled against; it protected the slab edge insulation from UV light and mechanical damage…foundation, insulation and protection…all in 1 step. He was named Canada’s “R2000 Builder of the Year” for 1989.

I agree with Roy, but i would also poke my head out the window and take a look around the house, i know it my neck of the woods there is a lot of “bed Rock” it’s not uncommon to see slab on grad foundations.

If under slab ducts are present, I would mention in report that mould could be present in ducts and to have inspected / cleaned by a professional prior to purchase…