I’m pouring a floor in a room in the cellar because code says the oil tanks have to be on a 4” pad, and they are enforcing it via the fuel delivery guys signing off (I have to do at least the pad). My house was built a couple of hundred years ago and has a stone floor in the cellar. The room with the furnace has a cement pad the furnace sits on, and the stone has been removed from most of the rest of the room. Looks like gravel underneath (well-drained glacial soil here). Most of the gravel floor is 8” below the top of the existing slab, so I’ll be bringing in some gravel to get the new floor even with the existing pad. I’m also doing a larger pad outdoors for a shed, and will be layering up 2’ of gravel on one end. Rental plate compactors range from 3000 to 6600#. How big a compactor do I need to rent? (Walk-out access to cellar)
first for the basement I would figure the extra cost of the concrete vs the cost of gravel, hauling and the amount of work to get it down there. I have found depending on the size it was easier to just add to the concrete rather than having to get and haul gravel. Depending on the amount of concrete you need you might get a better per yard price or they might not add a delivery charge for which some do for a small load. Basement I would get #57 limestone and place concrete on that. Out side depending on drainage you could do #57 limestone which would drain well or if you want a little more solid 304 which is #57 with the dust in it, this will compact and pretty much turn solid after a while. 3000# compactor is plenty just place and compact in 4" placements. Biggest concern in raising 2' would be containing the gravel. Not sure if you are going to do a containment or slope it away if sloping it you will need to go out about 6-8' to prevent movement. You can cover the gravel with soil and plant grass after.Do not try and contain the gravel with a soil berm it will wash out.
Great - thanks! I was hoping you or fuelrod would see this. 2’ is the max depth, and I’ll be sure to add ample taper. In the pic below the pad runs up from the rock on the right (end of trench for electrical) to the short stake with yellow flag (20’), and then a woodshed continues on to the left, up to the hat on the ground (in line with the left side of the big rock). I can cut the slope above and have a reverse-tilt/swale to send water away, which would reduce the 2’ lift to something less. I told the local gravel pit operator what I was up to, and the second pic is what they sent.
I didn’t go quite that far when I saw it, but it definitely has more fines than I was expecting. I have a few yards of crushed stone I can use, too.
Could use what we call a jumping jack compactor too...at least in the basement. Easy for two guys to carry in/out. Might take too much time outside though...
I would not bother compacting the basement if he uses #57 limestone. what the gravel guy sent does have more fines than I normally see but after you compact that it will be like concrete. Also next load might have more stone it does vary. A little hydration on that and it will get hard.
Flamestead I had to do this last year for apartments. All I had to do was pour a 4 x 8 pad for tanks to sit on. I framed with 2 x 4 poured pad and put tank on pad and passed. Anything else is extra..
I wasn’t familiar with #57. Understanding Crushed Stone Grades | Ozinga Blog I checked with my cheap laser level at dusk (so I can see the line), and I’ve got nearly 3’ of drop across the 32’ from the back of the woodshed to the front of the pad. Looks like a small rock retaining wall at the back of the woodshed might do the trick. I have no lack of rock, but wish I were more artistic with it. The pad area itself has 15” of drop. I’m hiring a neighbor who retired from his concrete business but can’t sit still in retirement. He currently has family visiting, so I’m not pestering him with these questions, but am trying to get as much done as I can ahead of him, plus I’m out on vacation. Thanks again!
The Mrs has been unhappy with this room because moss grows on the dirt floor (she calls it mold), so she is looking forward to getting a nicer floor. The foolish thing is the tanks passed the initial inspection a couple of years ago, but we had a new furnace installed last Fall and they said this had to be done now.
Your not asking much of the slab in your bsmt. I'd just bring it up with 3/4" crushed stone to allow for 4" of 'crete to hit your desired elevation, put down the thickest poly you can find locally and go get a case of beer for your retired friend. From your description, without fines, you should be fine adding 5-6" without compaction. Just "walk it in" some. If your buddy wants some wire, bar or fiber, he'll let you know. He'll be both quality control and inspector ultimately. For your shed, it sounds like your small rock retaining wall is what I'd do with a fill of that depth, along with possibly allowing 4-5' of walkable space between the new shed wall and your retaining rock wall that even a 3', you don't want to fall off. Like iron pony said, fill the deeper areas in 4-5" "lifts" compacting as you fill and get a gravel with fines in it to "lock" it together. There's not much limestone up here and any local crushed stone will be fine. Gravel/stone language is very regional and in many places, the name is given by the state along with its specs. for State contracts mostly associated with road const, so just ask for at least a 1" minus or if they have it 2 or 3" will pack better. Any plate compactor will do what you want in 4" lifts. Don't forget, we'll need plenty of pics
Thanks for the advice, particularly leaving it to the experienced one to decide regarding bar, fiber, etc. I tend to over-engineer, partly to make up for inexperience and partly because I hate seeing things fail due to penny-wise shortcuts. I wasn’t clear on saying where the retaining wall was being proposed. I’m thinking of doing a deeper cut and have the wall on the uphill side. It will be damp at times in the woodshed floor, but I have some rubber roofing material I could put on the backside of the wall, and there isn’t much ground further upslope to send surface flow in that direction. This shed is actually a sugar house, but I’m building it with an eye toward being useful to the next owner. I’m thinking of putting 2” foam under the slab. Is this overkill for such a relatively small building, especially since it is a floating slab (so no perimeter insulation down to the frost line)?
Drainage is the best goal. That is further out perimeter (up hill) surface water and close in (roof run off ) having a positive slope away from your slab. Proper grading is the best and cheapest way to NOT get into a fight with gravity, who's rules don't bend and are consistent. If you decide to foam under the slab, extend it out beyond the slab edge 2'. This will help in keeping the cold air from under the slab and possible heaving. You can cover the extended foam with gravel and a little slope in the foam away will be a big help. There's good info (that I learned from) on the Internet - try "frost protected shallow foundations" and "picture's".
This ledge (or Big Rock) might determine the grade. First day on the job running the cleanup bucket on the excavator? Yup!
Run of the mill rock I found in the electrical trench, on the left. Rock of unknown size to the right of the hat. Streak of ledge in upper right corner of the pic.
The ledge (bedrock outside of NE) will limit your elevation choices, but clean it up and gravel it flat. It's not going to heave! Gotta look on the bright side.
