Expansion joint between floor and wall

[hockey88fan]

My walls are all concrete, atleast where the floor will be meeting the wall. I'm going to be pouring a 4" concrete floor that has radiant heat tubing in it. It is recommended I insulate the slab underneath but also along the perimeter. I'm have trouble picturing the way it's supposed to be done along the perimeter since there will be an expansion joint along the wall, and in addition the insulation is 2" thick which would make an unsightly finish where the floor meets the wall. If anyone can explain how it s done I'd greatly appreciate it, thanks, Kevin.

 

[ScaldedDog]

There are experts on here but, since they haven't responded yet, I will.

I used the 2" foam (I used Dow Hi-load 40) as the expansion joint, by placing the vertical pieces along the walls first, then the flat 4x8 sheets on the base beneath the slab. My "side strips" are fairly flush with the top of the concrete, then I used Sikaflex over top of them to make it a little more attractive and durable. Some folks here will cut the foam at a 45* angle, and that allows the concrete floor to go all the way to the edge. The concrete isn't quite as strong at the edge that way, but I guess it's strong enough.

You can kinda see how I did mine here...

Mark

 

[hockey88fan]

There are experts on here but, since they haven't responded yet, I will.

I used the 2" foam (I used Dow Hi-load 40) as the expansion joint, by placing the vertical pieces along the walls first, then the flat 4x8 sheets on the base beneath the slab. My "side strips" are fairly flush with the top of the concrete, then I used Sikaflex over top of them to make it a little more attractive and durable. Some folks here will cut the foam at a 45* angle, and that allows the concrete floor to go all the way to the edge. The concrete isn't quite as strong at the edge that way, but I guess it's strong enough.

You can kinda see how I did mine here...

Mark

Thanks! Also, is that rebar laying on top of the pex with wire mesh underneath the pex?

 

[ScaldedDog]

Thanks! Also, is that rebar laying on top of the pex with wire mesh underneath the pex?

It is. I like strength, and hate cracks. The mesh doesn't do much down that low in the slab, other than make a for easy attachment of the PEX, so we put rebar in, as well. The garage floor is 6" thick, and has very few cracks, and none more than hairlines.

Mark

 

[darkk]

Stand the foam on edge against the outer perimeter and trim off the top 2" so it is buried in the concrete. That 2" certainly isn't going to make any noticeable heat loss...

 

[MPH]

I cut the 45 degree angle at the top of the foam which allowed the cement to go all the way to the wall. As far as breaks and cracks due to thin cement next to the walls... so far so good.

MPH

 

[hockey88fan]

Stand the foam on edge against the outer perimeter and trim off the top 2" so it is buried in the concrete. That 2" certainly isn't going to make any noticeable heat loss...

Good point, I wonder if I even need the perimeter insulated being my building is built in to an 11' bank and surrounded by earth on 3 sides, hhhmmm......

 

[egads74]

I can't remember where... but I read that the slab can loose 30 percent to the outside when not insulated. I would be concerned on that 2 inches of no insulation in a 6 inch slab (33 percent of 30 is a lot of loss).
In my application, I went vertical with that 2" insulatation to the top of the block (all 2 rows of block above the floor is covered w/ insulation).

A foot of dirt has an R-Value of 1.