Compact Necessary Or Not?

lazerguy

Hi fellas,

It's been one year since I poured the foundation wall for my new garage.
The wall is 8 in thick and 4 feet high.

I am now prepared to backfill the foundation (inside and out) with Class B sand.
Normally, I would lay the sand in 1 ft layers, and compact each layer with a vibrating plate.

Now, I won't be ready to pour the slab until next summer.
Could I just dump the sand, level it out, skip the compaction and wait for Mother Nature to do the job?

Thanks!

finehomes

You can't be serious???

user50444

that used to be the "old" method which does in fact work, but usually you need to literally flood with water. i dont know the difference in cost per yard but 3/4" screened stone works great with compaction. i have seen hollowed out sub grades where sand is used. where we cut out cracked sections in ... garages + replaced. not one excavation firm in this area compacts 3/4" stone in lifts for garages... compacted after we strike grade...

many names

I honestly don't understand sand,why not just use a structual fill and compact.I would be more concerned about inside wall than outside for obvious reasons.There's no shortcuts for a proper job.

JDavis21835

Sand is not hard to understand. Its granular material, similar to stone. Around here it is a common material. If you find stone around here, it came from somewhere else, most likely on a lake freighter. Making it a lot more expensive. The key to hitting numbers on sand is moisture. Last parking lot I did with sand base, I had my moisture at 11.5%, and was making 100.5% compaction. To the original poster, since its going to be until next summer you will be fine. Add more material than you will need, let mother nature do the job for you. You should have a little to cut out when your ready, but its better to have all of the material there, and settled out. If you are paranoid after that long period of time, flood the area with water, and then cut it down.

mics_54

I agree with JDavis...you'll be fine.

With a couple of caviats..is the material benieth the site permiable?
Does the site have decent drainage?
You don't want trapped water freezing and then pouring before it thaws next year.
IE: a hole in clay filled with sand will still just be a sandy waterfilled pond. Compacting the sand with water only works if the water will drain out.

lazerguy

Thanks for the advice!!

Yeah, around here sand is $80 Canadian for a truckload, while stone is 3 times more expensive!

There is excellent drainage under the sand, the underlying rock being quite permeable.

Just to see, I did rent a vibrating plate, but I saw very little compaction taking place.
Just walking on the sand seems to compact pretty well as the sand is moist.

So I'll make it a little overfill, then cut out the excess next year.

Thanks again. Cheers!

bystry

We took old home and its basement out.
The new garage of the new home will have to go above where old basement was. So the hole needs to be backfilled.
Any ideas on the best and most economical way of handling it?