Insulation and concrete form?

[StupidSheet]

Well I have a couple questions. First one is do I include the insulation into the form or do I just put it up to the concrete after the pour and backfill around it? What's the best way? Second question is would OSB be sufficient for making the form if supported properly?

 

[guilld]

The turned down slabs I have seen they use 2x10 or 2x12 to frame. I am not sure about insulation but I see you are up north so it probably may need insulation. Also you probably need to see what others are doing slab wise in your geographic area.

 

[ez-duzit]

Seal and insulate after pulling the forms, which can be made from anything stout enough.

 

[StupidSheet]

Thanks guys

Seal and insulate after pulling the forms, which can be made from anything stout enough.

What do you mean my sealing?

 

[ez-duzit]

It is my understanding that, in many areas, it is SOP to seal against water penetration from the backfilled earth. No?

 

[StupidSheet]

It is my understanding that, in many areas, it is SOP to seal against water penetration from the backfilled earth. No?

Are you talking about ground water leaking into the insulation?

 

[dirttracker18]

Mine went in before the pour right against the forms and sealed ( with sheathing tape ).

All the ones I've seen or been involved in were the same.

 

[ez-duzit]

Are you talking about ground water leaking into the insulation?

...into your basement/building.

 

[wssix99]

Why not use ICF? (Insulated Concrete Forms). That would eliminate the need for forms and the extra step to attach the insulation.

 

[theoldwizard1]

Why not use ICF? (Insulated Concrete Forms). That would eliminate the need for forms and the extra step to attach the insulation.

Are wee talking footing/foundation wall for a garage or are we talking about a basement (living/storage space inside) !

ICF is probably overkill for for just a garage foundation wall.

The original question was

... do I include the insulation into the form or do I just put it up to the concrete after the pour and backfill around it? What's the best way?

Typically applied after the forms a stripped. There are several different methods for attaching it. All use a large typically plastic "washer" to spread the load. One style is an all plastic device that looks a little like a nail with a very large head. You drill through the foam into the concrete and pound it in with a hammer. Friction holds it. I would put something over the foam to protect it when back filling unless you are using sand.

 

[wssix99]

ICF is probably overkill for for just a garage foundation wall.

For a contractor, that might be the case but for a do-it-yourself job, it might end up being better due to the lower labor cost and no need to rent forms.

 

[StupidSheet]

Thanks guys! This is for a concrete slab with a 16"x16" thickened edge just to clear up some confusion. I just started do the form today and wanted to know which way to do it because if I put it inside then I have to frame bigger. Happy to hear it can be done both ways.


One more question. Do most people insulate the sloped part of the thickened edge. On a local forum I noticed one guy that didn't bother. He also put the vapor barrier on top of the insulation.