Raised Floor question

[chris ciechoski]

After lurking about reading through all the threads I could I have finally got around to setting up my "shop" into a useable space and have come into my first obstacle of what I imagine will be many. I have a spot carved out in my garage to set up my shop that is 18 x 20.

The garage has a dirt floor that is 1" of pea gravel over a heavy clay floor. The obstacle that I have run into is that I cannot get concrete poured into the garage due to the proximity of the garage to my property line. Given that I have 3 options and am looking for advice as to what has worked for others on the forum.

Option 1: Dig out 6" of clay. Lay down a vapor barrier and compact #1 crusher run in 2" lifts until I reach 6" and use that as my floor.

Option 2: Dig out the pea gravel and till up the clay and compact it with a plate compactor.

Option 3: Compact the dirt and pea gravel that is currently there. Lay down a vapor barrier and build a raised floor using PT lumber for joists and then finishing with 3/4" plywood

I do not have any heavy machinery to date but just need a solid and level surface to work on. Any advice or sage words of wisdoms.

[Lon Crosby]

If you can get lumber into the building, even a reasonably good concrete crew can get concrete there. It can be mixed on site. Almost every rental yard will have a concrete mixer for rent. Concrete can be hauled in using a concrete buggy or the bucket on a skid-steer. Depending upon your soil -clay mix, you can create soil-crete. Lots of options including hiring a pumper truck to pump it.

[chris ciechoski]

Thanks Lon, sadly I have gone down the concrete road but was stymied by the town due to my garage being grandfathered into local ordnance governing the placement of permanent structures. They put the Kibosh on a cement pour immediately.

I have looked into soil cement as well but have heard mixed reviews about using it in the Buffalo climate. I may give it a shot on the car side of my garage as that is also dirt. I know I will probably need to experiment with the mixture.

[Pat Barry]

Would it meet the city requirements to just put concrete pads for certain pieces of equipment?

If so, the pressure treated 'deck' design should work for you, you could work around the concrete pads.

I would go the compacting route,double up the vapor barrier, build the deck structure, insulate under it with pink foam board, add the decking boards.

One question though, is the earth relatively dry in the space? I mean, no moisture problem due to poor drainage?

[chris ciechoski]

I can pour concrete pads if needed for larger pieces of equipment.

The earth is relatively dry. The clay holds a good amount of moisture during heavy rains/snow thaw which is expected but i can dig a 8" hole in the garage and it won't fill with water.

How thick you think on the vapor barrier if I am doubling up?

[Mark Rakestraw]

I did something similar just down the road from you in Rochester, NY. I used pea gravel to level out the dirt floor of a barn, put down 2 X 8 X 16' (laid flat) pressure treated boards leveled in the pea gravel, put down 6 mil plastic then regular plywood subfloor over that. I don't remember exactly, but there wasn't much space between the 2 X 8's. I think I had 5 boards per 4 foot plywood width, with 1/2 of both the outside boards sticking out to support the adjacent pcs of ply. Not necessarily inexpensive, but it worked quite well. If you needed to insulate you could lay down 1" foam board on the ply then add another layer of ply on top of that. I did this on the mow floor of the same barn. I've since moved my shop so I took most of it up. I did leave one section though so I could take a pic for you if my description isn't clear.
Mark

[chris ciechoski]

I did something similar just down the road from you in Rochester, NY. I used pea gravel to level out the dirt floor of a barn, put down 2 X 8 X 16' (laid flat) pressure treated boards leveled in the pea gravel, put down 6 mil plastic then regular plywood subfloor over that. I don't remember exactly, but there wasn't much space between the 2 X 8's. I think I had 5 boards per 4 foot plywood width, with 1/2 of both the outside boards sticking out to support the adjacent pcs of ply. Not necessarily inexpensive, but it worked quite well. If you needed to insulate you could lay down 1" foam board on the ply then add another layer of ply on top of that. I did this on the mow floor of the same barn. I've since moved my shop so I took most of it up. I did leave one section though so I could take a pic for you if my description isn't clear.
Mark

Thanks Mark. That is pretty clear. How did the PT hold up on the gravel?

[Mark Rakestraw]

It held up well, but wasn't really down that long before I took most of it up. I knew there was no standing water in the barn at any time and the pea gravel was thick so I assume it would last indefinitely. You could put the vapor barrier on top of the pea gravel, then lay the 2X's if you think it will be wet too much of the time.