I'm in NE PA and am going to build a steel prefab quanset style storage shed for tractor and implements ( 20' x 30'). Will be quite crowded I know. I want to do it slab on grade rather than have to dig 42" footers. The prints from the building's company calls for 16" tall x 10" wide footers to attach the building to. Local code requires slab at least 6" thick with at least 6" stone beneath. Do I excavate 6" to accommodate the stone, leaving the footers sitting on the stone extending up 16" to the level of the slab? Or does the stone go inside the footers and only the slab on top of stone. In that case, I'd need about 10"of stone to end up with 6" slab? I'm confused. Neither the local jurisdiction nor the building very helpful. If I have to go 42", I'm OK with that, but it seems excessive. HELP!!!
SLAB ON GRADE
- Thread starter flINTLOCK
- Start date
- Views: 5933
Sounds like your local codes call for two things:
- 6" of stone under any portion of concrete
- All concrete must be 6" thick
So .... given that your building company calls for a 16" x 10" footer, you will end up having to dig at least a 10" trench. Here is how I came to 10" ...
Assuming you start out with a flat piece of land, and add 6" of gravel to the "middle" non-footer portion of the slab and add the required 6" of concrete, you will now be 12" above the original ground level. Since you know your footer needs to be 16" of concrete plus 6" of gravel, that part will be 22" thick. Since you don't want to have to add extra fill to the middle, you have to dig down the difference (10" inches).
By the way, using your measurements, here is how much material you will need: (these are exact measurements ... I would add 10% - 20% to your order for slop)
11.11 cu yards of stone
13.6 cu yards of concrete
Good luck
- 6" of stone under any portion of concrete
- All concrete must be 6" thick
So .... given that your building company calls for a 16" x 10" footer, you will end up having to dig at least a 10" trench. Here is how I came to 10" ...
Assuming you start out with a flat piece of land, and add 6" of gravel to the "middle" non-footer portion of the slab and add the required 6" of concrete, you will now be 12" above the original ground level. Since you know your footer needs to be 16" of concrete plus 6" of gravel, that part will be 22" thick. Since you don't want to have to add extra fill to the middle, you have to dig down the difference (10" inches).
By the way, using your measurements, here is how much material you will need: (these are exact measurements ... I would add 10% - 20% to your order for slop)
11.11 cu yards of stone
13.6 cu yards of concrete
Good luck
dirtworksequip
Veteran Member
- Joined
- Jun 3, 2006
- Messages
- 1,463
- Location
- Wheeling, WV
- Tractor
- 2006 JD 3520 w/cab & 300CX loader. 1995 JD 870 w/440 loader & 8b backhoe.JD 455 w/54" mower deck.
Why couldn't you do a monolithic pour. Level the building area. Mark the inside of the footers with marking paint.Cover that area with 6 inches of stone. Dig the footers into the ground 4 inches. Build form boards on the outside of footers 12 inches high. Put whatever rebar your need in the footers and slab area. Then pour the footers and slab together. The 6 inch floor over the 10 inch footer with give you the 16 inches for the building to sit on,plus a 6 inch thick floor area.The only problem I can see is keeping the stone 6 inches thick where it runs up to the edge of the footer ditch.
I don't know if that is what you where looking for in a end result or not?
I don't know if that is what you where looking for in a end result or not?
Skipping the stone underneigth the footer would be ideal but each building dept is different.
flintlock, no big deal about the gravel by the edge of trench, just slope it back and in that spot there will be more concrete ... I have never seen a BI give anyone a hard time about that
flintlock, no big deal about the gravel by the edge of trench, just slope it back and in that spot there will be more concrete ... I have never seen a BI give anyone a hard time about that
BHD
Veteran Member
a reasonable easy way to build a form on the inside of the footer to keep the stone in place and leave in place is to use pieces of re-bar for stakes, and then some (corrugated) roofing tin as the form be careful putting the stone or gravel up to the form (it will become easily self supporting as soon as cement fills the footer up), (the steel and tin, will not decompose to any great extent, and even if it does, It will NOT leave any voids).
form up the out side edge of the footer and slab to floor height.
that way you can do a one piece or monolithic pour,
form up the out side edge of the footer and slab to floor height.
that way you can do a one piece or monolithic pour,
BHD
Veteran Member
toolaholic
Silver Member
- Joined
- Sep 4, 2005
- Messages
- 144
Good idea to set the slab above the outside grade 6" You don't want snow melt water flooding your shop ! Try to find 3/4" crushed concrete ,instead of stone .Here it's $35 yard stone $12 ton crushed concrete and clean! no brick,metal or wood debrea.
EdC
Gold Member
Wow
12 bucks a ton for crushed concrete. I am re-doing our driveway and here in Eastern WA it is 5 dollars a ton. Do I feel better.
Ed
12 bucks a ton for crushed concrete. I am re-doing our driveway and here in Eastern WA it is 5 dollars a ton. Do I feel better.
Ed
jimmysisson
Veteran Member
- Joined
- Jul 11, 2005
- Messages
- 2,358
- Location
- W.Mass
- Tractor
- 1993 NH 2120 (the best), 1974 MF 135 (sold, but solid), 1947 Farmall A (bought, sold, bought back, sold again), 1956 MH50 lbt (sold, in 1980, darn it)
Yes. In Mass, the code calls for footings below frost depth, 48" here, and it's right to require that. We have built several pole barns (not sure what you're building) with PT 6x6s set in concrete below frost, and the slab floating on GOOD gravel fill at grade - works just fine. As for a perimeter-supported building, it should bear on frost-free undisturbed or compacted base. Of course if you wait a few years PA will be warmer and they may change the frost depth requirement!
Jim
Sorry, re-read your post, not a pole barn. You need the deep footings.
Jim
Sorry, re-read your post, not a pole barn. You need the deep footings.
