Stonedust. It'll fill holes and packs hard. Dirt and gravel will both move more easily under the mats, in my experience. We did our stalls with stone dust three years ago and they're still practically perfect.
Rent a POWER TAMPER to do the hard work for you. It can shake the air out of your ground fill, pack down the stone or dirt you are using. I recommend using it about every 4" of fill you lay down. Get each layer firmly packed down, then do the next layer.
We ran a 2'x4", 12ft long, both length and width wise, over the top stonedust surface, with a long level on it, to make sure the top layer was actually FLAT. You use the 2' side on the ground, so you can push off high places as you pull it across the stall. You want a full span length of board so it catches the whole width and length of the stall, while keeping those center bubbles in the middle of the level's lines. Does sound rather "picky", but you figure that any dirt under a horse, mats or not, is going to settle a bit more with time. Starting with floor as level as possible, will reduce the amount of holes or any low spots that can develop under the mats.
Tampers are not real hard to use, though a bit heavy to load and unload out of the truck. I have rented them for garden paths, as well as the stall leveling. Make sure the rental guy shows you how to turn it on and off. Make a LOT of passes over the stonedust or other layers, to get them packed as hard as possible.
Power tamper does a MUCH better job than hand tamping could think of doing!! Weighs more, vibration of the plate works your fill down into empty spaces. This packing dirt and fill is the job a power tamper is designed to do. Easier on YOU than slamming a hand tamper down 10,000 times!
We used stone at first, machine tamped it too. Critters (rats primarily) have benn able to dig away under the mats and cause movement and pockets. We are now in the process of floating each stall with concrete. I like the concrete WAAYYYY better. I wish I would have done the whole barn in concrete from the start!
I had cement poured so I wouldn't have the rodent problems, really don't have a problem here, but wanted to stay flat, had done stone then sand years ago and it pealed up over time a huge pita. Ended up pulling the mats out, and eventually getting the cement and doing it right.
Years ago I put in stall grids over crushed granite. Then filled and packed the grids with same material. They have held up extremely well, but in one stall, I decided to try some mats over the stall grids for extra cushioning. I spent the extra money and got the interlocking ones from Tractor Supply. This is the best stall ever!!!! Love the interlocking mats. They lie perfectly flat. I installed them four or five months ago, and no issues at any of the interlocks.
Last edited by ToTheNines; Feb. 18, 2013 at 12:31 PM.
We use stone dust too. We've never rented a tamper, but there is a definite advantage to doing so. If you're not going to do the tamper, level as best you can, and water every day to settle the stone. refill low spots as needed and re-water before the mats go down. Eventually the mats will have to come up and be re-leveled, but it depends on the horse. I've got one stall that has never had to be fixed (neat-freak horse) in the 11 years it's been in use, but generally we'll re-level a stall every couple/few years.
My favorite stall is one that has those plastic stall grid things in it. A friend decided they didn't like them, so we re-used them. They're perfect for the little mare who lives in that stall. She pees a lot and it drains well. And she hasn't harmed or moved them with her impatient pawing.
Yes, you can buy stone dust in bags, but you really don't want to do that except for when you need to add a bit in a very small area. Get a truckload delivered (figure out how many cubic yards you need and order that). Deposit it in the stalls by wheelbarrow or small tractor bucket if space permits. Rent the tamper (here it's called a plate compactor). It's really easy to use so you can't really get it wrong. Level it with a 12' 2x4 or something similar. If you are not comfortable doing the leveling and compacting you can get a local landscape company to do the labor, since it is the same thing they do day in and day out when prepping sites for laying pavers.
and make sure you have help lined up.....moving stone in any form is miserable if you don't have enough people to get it done, otherwise it takes forever and will kill your back. Machinery is an awesome thing here.