Outside Perimeter insulation

[nate379]

I have radiant heat in my house and attached garage.

There is 2" foam on against the slab and also on the ground. From what I can tell they used 4x8 sheets, cut what was needed for the vertical and put the leftover on the ground. They end up being around 3ft wide.

Question I have is how important is that insulation? I don't have any on the front of the house at all. One portion has a concrete porch, so no reason there.

How about in front of the garage?

The area where the dining room is doesn't have any either. This is between the porch and garage. I was thinking of planting flowers there though, so not sure if I'd be smart to put foam down?

Is there any reason for the foam to be overlapped? I dug out the back of the house today and moved the sheets so they weren't. Otherwise it felt hollow when you walked around the house and in some places it was springy.

 

[tdkkart]

The previous owner of my place built a 16x30 room, with radiant heat in the floor, in the back of the 30x40 pole building. Did everything right except didn't put down and perimeter insulation.

This spring when I started to excavate the remaining 24' of the building in order to pour the rest of the concrete, my first step was to trench around the inside of the buildng to put down insulation. What I found, was that after heating the smaller room all winter, the ground was not frozen in a 4' wide band all around the existing heated slab.

How much good will putting 2" foam board around the perimeter do?? I'm not sure of the exact numbers, but one can pretty much surmise that keeping 4ft of ground above freezing is gonna take ALOT of energy, so anything you can do to slow the transfer of heat will have to do some good.
I guess I'll find out this winter. I kept detailed records of daily usage last winter, comparison should be pretty easy.

 

[nate379]

I have the vertical edge insulation around the whole house other than the porch and front edge of the garage, but I was talking about the foam that was layed flat on the ground.

Should I add that in front of the garage and dining room, or is it not that important?

 

[tdkkart]

From what I've seen, insulation laid horizontal just under the ground is supposed to be roughly equivalant to vertical edge insulation, ie a 2ft wide band laid horizontal is supposed to be roughly the same as putting it in 2ft vertically.
Seems odd, but I guess anything you can do to keep the frost from going down will work.

 

[nate379]

I dug most of it up today to fix the sheets. One side of the house I haven't done yet because it's about 1ft down and in super hard clay. It took me about 2 hrs to dig out an 8ft sheet!

From what I can tell the only place that doesn't have any foam is in front of the garage. I'm guessing it's because the weight of vehicles would ruin the foam?
If that isn't the case I can easily dig it up and put foam down. I have a stack of 2" foam to use up anyhow. Contractors left it at the house a while back.

 

[krooser]

I insulated the basement of the house I built in 1975 with 2" blue styofoam. It had an exposed basement so only three sides were done but I think it helped keep the basement warmer... I lived in the UP of MI at the time.

 

[nate379]

They did the house next door today and insulated in front of the garage as well. (where you pull cars in/out)

I think I'm going to dig up my driveway and do it as well. Ain't like it's that much more work... already dug around the rest of the house.

I was hoping to get more info from here about it, but I guess not too many folks have radiant heat?

 

[nate379]

Dug up the driveway today and put down some 2" blue board. Did against the slab and then 2ft out.

Electric company came over with the mini excavator to bury my power lines on the other side of the house and went ahead and buried the foam for me! The guys wouldn't even accept a rack of beer

 

[jolakki]

Thats normal stuff here in FInland.
Atleast 6 feet around the building plus vertical with 4inch styrofoam.
If your slab is directly on the ground then 8 inches under the slab.

 

[jolakki]

From what I can tell the only place that doesn't have any foam is in front of the garage. I'm guessing it's because the weight of vehicles would ruin the foam?

There are different kind of foams and some of them can easily take the weight of vehicles.

 

[nate379]

Yup it's on the ground. 2" under the slab, 2" on the vertical and 2" out on the ground 2-3ft from the slab. Must get cold in Finland? Here it only gets down to -30*F many a couple times a year, sometimes it doesn't.

I was suprised this winter the snow was not melting at all around the house. The last shop I worked in had radiant heat and snow would be clear 5-6ft out from around the whole building.

Thats normal stuff here in FInland.
Atleast 6 feet around the building plus vertical with 4inch styrofoam.
If your slab is directly on the ground then 8 inches under the slab.