There’s a small stone retaining wall next to my house that’s settled a foot or two over the last 60 years. Now tilted severly towards the house. It butts against the house and I presume it was laid on uncompacted fill. Does fill ever settle entirely? If I tear out that wall and rebuild it, is it going to sink again? Any idea what I should do for footers to minimize that? Knowing the builder, there are probably no footings at all under the existing wall. New wall would be block with brick veneer, 3 feet above grade, about 10 feet long. Any simple way to test the soil without getting an engineer?
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I'm a novice, but I know the best friend of the homeowner is the inspector. So if you pull a permit, he'll look out for your best interest. I hear so many stories of folks doing stuff w/o a permit, and they get snookered. But then again, your local municipalities may not require a permit for a retaining wall.
No, don't need a permit for this. Its decorative, not structural. And, it can be considered a repair. I know the inspector. He doesn't know any more than I do.
Bob
I presume it was laid on uncompacted fill. Does fill ever settle entirely? Not until it becomes solid rock. But after 60 years most of the settlement will have occured and what comes next will be measured in small fractions of an inch.
If I tear out that wall and rebuild it, is it going to sink again? maybe. but probably not enough to worry about. If it's taken 60 years to get the the stage were you must replace it, it's replacement should last another 60. you can probably build on the surface reamining after you remove the existing wall.
Any idea what I should do for footers to minimize that? Knowing the builder, there are probably no footings at all under the existing wall. New wall would be block with brick veneer, 3 feet above grade, about 10 feet long. Any simple way to test the soil without getting an engineer?
I don't know of a "simple" test but for a 3 ft wall comercial retaining wall block installed in accordance with then manufacturer's instructions should be sufficient. Retaining walls usually fail because water builds up behind the wall and either increases the load on the wall or softens the soil on which the wall sits, or a combination of both factors. One of the keys to longevity is keeping the soil behind the wall and its foundation relatively dry. Another is to lay the wall back into the slope some. Frost heave during winter could also be a problem, but without knowing where you live the fact that the existing wall is still there after 60 years suggests that frost is not a major influence.
The following suggestion is possibly overkill but for a foundation you could use 8in of free draining gravel wrapped in a geotextile filter membrane with a slotted pipe to carry any water away from the wall.
Ian
Thanks. The wall is sort of a mess; part dry-laid stone, part mortared, concrete cap. I think there's plenty of drainage through the stone now. I was thinking of doing it with brick&block rather than ready made retaining blocks. It would match the house better. There are also site-made concrete steps at one end. Very uneven, spalled and tilted. 3 treads. They need replacement too. Footers here need to be 18" below grade. I was thinking of maybe just digging new footers a foot away from the existing wall, build the new wall and leave the old wall buried. Its a fair lot of rock to move. If I knock off the cap, the rest would be buried. I'd put drains along the footers and leave weep holes in the bottom courses. Does that sound reasonable? I'm on hillside and there's a lot of runoff, but no special water problems right in that area.
The settling can be taken care of by compacting the soil below the frostline.
For tilting, bury bury half the height below ground, (3' high = 1 1/2' below ground.)
To prevent uplifting from frost heave, bond the wall to the footing with rebar 2'OC and make the footing twice as wide as the wall is thick. The top of the footing must be below the frost line.
Back fill between the two walls with coarse gravel for drainage, tilting, and uplifting.
Weep holes will work, but a drain under the backfill will work better and keep looking better over time, if you have a place to bring the end of the drain to open air.
SamT
Bob
look at SamT's post. I've not much to add. Just remember that if you dig new footings in front of the wall there is a chance that the wall will fall on you. How big a chance I can't say without a whole lot more info. Where the wall abuts the house you want to make sure that you're directing water away from the structure, especially if you put a new wall in front of the old and fill the gap with gravel.
Ian
I think that will work out. I'll set the footings 18" deep, so that's half the wall height already. Hadn't considered the existing wall falling in, but I will now. Maybe I can put the new one a little further out to reduce the risk of that. If I do 8" block plus brick, that would mean a 24" wide footer and I'd think its practically impossible for that to sink or tip with just a little wall on top. A fair lot of work, but I really only want to do this once.
>>settled a foot or two over the last 60 years. Now tilted severly towards the house. It butts against the house and I presume it was laid on uncompacted fill.
Has it settled, tilted or both?
Potentially 2 different problems
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