slab on grade or stem walls??

[bimmer1980]

I am currently designing my own garage to be built in York, PA. I have a question on the footing for the garage. I would like to use a monolithic style slab that has the deepened perimeter for the footings. The deepened part would be about 12” wide (minimum) and 12” deep (minimum) and slope up to the slab thickness at a 45 degree angle. The slab will be about 4 to 5” thick. I’m planning to install radiant heat in the garage and I was planning to install at least 1” polystyrene and vapor barrier. Ideally, I will install 2” of insulation under the slab. This should protect against frost, etc. Rebar would also be used in the slab and the integrate footings. I would also be planning to keep it covered during the cure for at least 2 weeks (my ideal is at least 28 days). I would also be cutting joints at around 8 to 10 feet.

The site is nearly level and would require minimal grading. I’m planning to put down at least 4 to 6” of crushed rock or gravel. That will be compacted prior to placing concrete.

Is monolithic slab on grade permissible for my garage application?

Thnoughts on this?

I emailed the PA building inspector group as well, but I wanted your guy's thoughts.....

 

[Tman]

It is a great way to do the floor IF you won't get in trouble with the local authorities. My shop/house was poured the same way.

 

[Torque1st]

Check the local code authorities. They probably require you to get down below the frost line. !2" may work in Floriduh but probably not in PA.

 

[PAToyota]

Typically around here you do stem walls to get the footings below the frost line. I can't speak to your situation because I've never designed a monolithic slab for around here.

 

[bimmer1980]

Well, the plans review guy didn' tlike the idea of an insulated slab on grade. I would beg to differ, but I figure it's not worth arguing.... So, the next question--what type of stem wall? What have you guys done?

Options:
Poured footer with poured walls--options for form work or DIY plywood forms?
Poured footer with block walls--who laid their own block?
Poured footer with ICF walls--is this worth it for a stem wall?? any experience in them?

I like the idea of the ICF--form and insulation all in one. But I'm not sure on the cost and if it is justified. I do plan to install a radient heated floor....

Thoughts??

 

[PAToyota]

Poured footer with block walls--who laid their own block?

That's the route I took when I did it myself. Pretty straightforward. Took some time and built up some muscles doing it. This is also how most of the ones we've designed have gone.

Poured footer with ICF walls--is this worth it for a stem wall?? any experience in them?

ICF walls are going to be a lot easier to do on your own. I had a friend do an addition that way. ICFs are a lot lighter than blocks, easier to cut and stack, and then you just call the concrete truck. Chances are that it will be more expensive than block if you're doing both yourself. But then consider what your time and effort are worth.

Will reply to your PM later.

 

[walrus]

Many slabs on grade in Maine, it depends on drainage, soil types, insulation, heat in the building, how much steel etc

 

[BooUrns!]

I'm surprised that want you to build below the frost line that far south. Floating slab detached garages are quite common up here (you need to go very deep to get past the frost line).

If you're going to go stemwall, I also recommend the icf. Great labour saving product with the insulating features (plus stronger typically stronger conc. due to no from stripping and increased curing time).

 

[zeebad1]

Here is what we are doing with ours. Be it right, wrong, or indifferent....

We first dug down around the inside about 28". Then laid the foam blocks down on the bottom. (I got truckloads of 24" X 2X" blocks, 2 3/4" thick.) Then stood the one up along the wall.

I was wondering how to hold the inside foam in place, when my concrete guy suggested building the form as we did. He figured that will save me over $600.00 on wasted concrete.

The floor will be 6" thick, and the footing is 24" deep. I used the little pieces that I cut off for blocks to hold them apart. I'll take them out as they fill the trench with concrete.

The slab insulation will lay right on top of the edge of the inside blocks.