Originally Posted by Bridger51
BridgeMan - I'm with you. I have a ranch style home in Florida that has the underside of the slab becoming exposed due to a the yard settling. . . . . but how exactly do I make sure all the air is removed from under my slab from the outside?? Today is the first time I noticed how bad it is. Not more than 1 inch of air, but it goes back under the slab at least 1 foot. . . . Can I use a poly compound myself? This should be a DiYer....IMO. BridgeMan if your out there, you seemed like this could be an easy fix.
I was thinking of using a loose concrete or poly and letting it settle under the house than burying that under the dirt, But do I have to keep everything from sticking out farther than the current slab? Will only a couple inches laterally create different problems in the future?
If all you're dealing with is only an inch of settlement, extending just a foot under the slab, why not go the cheap (and easy) way? Which in my opinion would be dry-packing a pre-packaged concrete mix into the voided areas, working from the outside, and starting in the middle of any given void and working outwards to enable entrapped air to escape. Hardest part would be hand-excavating temporary "work stations" in the adjacent soil, to provide space for working a tamper back and forth after you've dropped in a load of slightly-stiff (no more than 2" slump) concrete, preferably off of slightly-sloped, intermittent planks. Installing the planks with gaps between them will provide room for working your tamper in a horizontal plane. Use a 2 x 4 in the flat orientation for the tamper, rounding the edge you hold to avoid blisters.
Doing it this way is economical, probably less than $50 for bagged concrete, depending on the size and extent of your house's voids. Ten 80-lb. bags of mud will cover almost 100 feet of voids around the perimeter of the house, assuming an average thickness of 3/4". And there should be no extensions of your work beyond the existing slab, as you can finish the concrete flush with the slab edges with a hand float (resin or mag) if poured stiff enough.