Insulation Under Garage Floor Slab

Dealing with the edges the foam insulation and two layers of plywood can add as much as 2 inches of height to the garage floor.

Insulation under garage floor slab.

There is no insulation under the slab. Through nearly all of the winter the temperature a few inches above the floor stays in the upper 30s f. The back ten feet of the garage structure is an unheated workshop area separated from where the cars park by a framed wall 2x4 and door. Pinning the apron to the slab is just doweling some 4 rebar into the garage slab at each door writes dave richeson.

The codes are silent about whether above grade slabs need to be insulated. Namely if you are only digging the slab you will need to take into account the thickness of the insulation since it will affect the depth of the slab. Concrete is cold and hard but an insulated concrete slab can make a heated garage significantly warmer and more energy efficient. Floor 1 garage 3 under slab 5 more ways to filter.

Insulate your garage to reduce energy bills and protect your garage against harsh outdoor temperatures. Average pir insulation will easily support normal garage loads under a 150mm slab. I am presuming there is a 4ft deep footing around the perimeter of the garage with no insulation. These codes do not require any insulation for slabs that are more than 12 in.

The first important thing to pay intention to is the depth of the floor slab. Consult appendix a table a6 3 1 in the 2016 edition for a tabulation of assembly f factors for slab on grade floors based on the arrangement and rated r value of the applied insulation. Below grade need vertical insulation at the slab perimeter. Really you can forget the imposed vehicle load and just work out the concentrated load which should be minimum 9kn for vehicles up to 2500kg.

Otherwise both codes require that slab on grade floors with a floor surface less than 12 in. The math is pretty simple the thicker the concrete floor insulation material the deeper the slab will have. Get free shipping on qualified under slab foam board insulation or buy online pick up in store today in the building materials department. 140kpa is the same as 140kn m which is a considerable load.

These f factors are acceptable for all slab on grade floors but you need to make sure. If this is the case then the frost will travel down the footing and make the floor cold and thus heat loss. Connecting slab and aprons tying rebar in the slab to sidewalls may not be necessary or even advisable but at least one post suggests that connecting the main floor slab to the aprons at door entrances is a good idea. The f factors for slab on grade floors are defined in standard 90 1.