Thermal break between slab and apron ?

[Bclinehand]

I am in the process of building a new shop...... The heated portion will be 32x40 with a radiant heated floor.....

My question is this...

I will be insulating under the slab with 3.5 inched of rigid foam and on the outside of the 4 foot frost wall with 4.5 inches of the same. Is there a way to provide a thermal break between the slab and apron where the 14' door opening is ?

thanks in advance
BC

 

[Randy in Maine]

I did not do my 2 x 8 foot door openings at the apron. It is not a huge heat loss. Concentrate on the thermal break between the heated floor and the unheated walls.

I used the 2" thick insulation about 16" tall leaving about 10" above the floor level and then covered it up with pine.

 

[jack stand]

They do make a foam expansion strip that comes in a roll. It's more of a commercial product and has a perforation down from one edge about 3/4". It is intended to be pulled off after the pour and it leaves a void to fill with a good caulk to keep out water, this step may not be necessary. I am not a concrete guy, but was recommended to me by a friend who is. I have also seen 3/4" rigid foam or "Celotex" cut into strips for this purpose, (expansion joint not thermal break) I don't see why it would not also provide a thermal break.