Author Topic: Fill dirt for under slab  (Read 635 times)


  • 5 O'Clock Shadow
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  • Age: 33
Fill dirt for under slab
« on: September 11, 2017, 09:12:23 AM »
Hi everyone,

I am in the middle of remodeling my bathroom.  During the process we discovered that a P trap was never installed so we did that this weekend.  I noticed that there are some void areas where dirt is missing.  I would like to fill these voids in with dirt but do not know what type of dirt to use. 

Has anyone had any experience with this?  I live in Texas by the way so foundation issues are very common, I don't want to put something in there that's going to make a bigger mess.

I will try to call a few foundation companies too see if they can give me any advice.

Thank you !


  • Handlebar Stache
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Re: Fill dirt for under slab
« Reply #1 on: September 11, 2017, 09:23:17 AM »
Just some clean sand, gravel, or about anything that you can compact, and that does not have organic material (top dirt, sod, roots, etc.) in it will work just fine.
Sounds like a small area, maybe you can just salvage a few buckets of material from somewhere on your property?


  • Handlebar Stache
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Re: Fill dirt for under slab
« Reply #2 on: September 11, 2017, 06:25:01 PM »

 I usually use sand because it is the cheapest for me to obtain and get it into place.


  • Handlebar Stache
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Re: Fill dirt for under slab
« Reply #3 on: September 11, 2017, 08:19:38 PM »
Yep, sand or fine gravel. My local masonry supply will sell five gallon buckets of both for a buck, if you bring your own bucket and load it yourself. Dirt isn't a good choice, and neither is a coarse gravel, as in bigger than peas. My favorite is available from  gravel suppliers and it's often called screenings, or stone dust. It's basically stone that's ground to the consistency of coarse salt, with finer stone dust mixed in. It packs extremely well.