Frost Protected Shallow Foundation Slab 1

[Big Jilm]

Good Morning All,

I'm designing a residence in a cold climate that is requesting a FPSF with a monolithic poured concrete floor slab. The soils are not expansive and the risk for movement is low. The soils report does not specify a structural slab. However, should I consider this condition structural anyway? Normally, I would specify slabs on grade (SOG) to be 4" or 5" and be separated from the sub/super structure and allowed to move if needed. While with properly selected and placed free draining gravel under the slab, I think the movement possibilities are low, because it is attached to the building it seems more like a mat foundation than SOG. What are your thoughts? How have you approached these slabs if at all.

Thanks for your time,

Jim

 

[canwesteng]

If it's a heated building and it's frost protected, it would be typical to use a thickened edge slab or other mat foundation.

 

[dik]

For heated residence, I usually use perimeter insulation in freezing climates. Dow has an excellent publication for this.

Dik

 

[Big Jilm]

canwesteng and dik, thanks for responding. To be more clear, I'm familiar with the FSPF perimiter desgin itself, I'm more interested in opinions regarding the monolithic slab and it's behavior. Would you design it as a minimally reinforced slab as they often are in residential or becasue it's attached, perhaps thicken it a bit and add reinforcing to span x distance, from thickened mid-span elements or similar like a mat?

 

[CivilSigma]

Here in Ontario, the Building code specifies that concrete or CMU foundation footing should be at minimum below the frost line which is a minimum footing embedment of 1.8 m if your basement is heated.

Also, if you are designing a simple 2 story detached home, then there are prescriptive foundation footing and wall thickness you can use (i.e. you don't have to design anything).

 

[HTURKAK]

In past, i used inverted bowl type slab foundations for 1-2 storey bldgs at cold climate. I wrote ( cold region inverted slab foundation ) searched the web. One of the pictures which you may adopt ;

 

[dik]

I've done dozens, if not hundreds of stiffened slab foundations in Ontario... They can be used...

Dik

 

[dik]

Some standard details, modify as needed... sometimes wrap the insulation up the face of the slab stiffening.

Dik

 

[Big Jilm]

Thank you all for your replies. Much Appreciated.