My sidewalk been down so long

March 13, 2025 3:57 PM

The sidewalk in my backyard is between 4 and 6 inches lower than the surrounding yard and my neighbor's yard. When it rains, the water pools on it and it's a river. During the winter, meltwater collects on it, freezes, and it's an ice ribbon. Can I just lay another sidewalk over it to bring it above the flood plain so we can walk on it in all seasons?

I'm capable of doing the work, just not sure whether it's a good idea. Here's the sidewalk if that helps. Note that the sidewalk itself is level, and it's connected to the concrete around our back porch and the steps leading down into the basement. But for whatever reason, the yards are significantly higher.

posted by goatdog to Home & Garden (10 answers total)

Decomposed granite makes a very wonderful path once it's rolled and compacted. Better than concrete ., water drains through it nicely.
posted by hortense at 4:04 PM on March 13

I would. Line up your expansion joints so they are in the same place. I'd also drill a few holes in the current side walk to set some rebar pins in to tye the two slabs together laterally.

The only drawback is you'll end up with a half step at the stairs.
posted by Mitheral at 4:08 PM on March 13

Doable. Mitheral rebar is a must. I do think that over time, it too will sink under the weight. I would be a little concerned that in the winter, water will get between the two walkways and freeze maybe causing some heaving. Also too thin on the new layer and it will crack if heavy weight put on it.
posted by JohnnyGunn at 4:55 PM on March 13

This is definitely doable and you definitely need to tie the two slabs together - both with rebar as described by Mitheral and with a solution such as bondcrete that will ensure the new concrete adheres to the old. Obviously, you need to thoroughly clean the top of the existing slab by pressure washing or something.

The issue of the half-step could be solved by removing the first few feet of the existing slab (shitty job, yes) so you can taper the new slab to line up correctly with the steps. Leaving a half-step at the bottom of a stairway is unsafe, especially for anyone with poor vision.

Alternatively, you could build a 'spoon drain' to the left of the path, letting water drain away from the existing path, assuming there is somewhere for it to drain to.
posted by dg at 5:23 PM on March 13

For the part near the stairs, I was thinking about removing the last 3 or 4 feet from the original sidewalk and putting in new concrete with a slope that rises to meet the new, higher sidewalk.

Do I put something between the old sidewalk and new? Gravel? Sand? (on edit, bondcrete it is). Thanks everyone.
posted by goatdog at 5:24 PM on March 13

When they took down my very old tree near the front curb which had heaved several of the concrete slabs creating a tripping and liability hazard I was surprised with what they did next: with a front end loader they lifted each slab and "parked" them in the street. Then they removed the tree roots, put down gravel to form a level base and then put the slabs back. This required underground utility lines to be marked. I know this probably would NOT work for you because it would probably be too tight quarters in your back yard. I just thought I'd mention this in case it caused you to think of a variation on it.
posted by forthright at 5:44 PM on March 13

Couple of things worth thinking about. If you were to remove any concrete to slope to meet the stairs you might be creating a slope of water towards house which is never good. I'd be very sure that no matter what water still drains awau from house. Another option that's usually quicker, easier, and cheaper is driveway/sidewalk leveling. They basically make some holes and pump leaving foam underneath. It's significantly less $ than new sidewalks (probably less than materials cost even). Friend had his entire drive and pool deck done for like $2k. The new driveway quote alone was $6k.
posted by chasles at 5:36 AM on March 14

I agree that sloping concrete toward the house is not a good idea.

Has the sidewalk actually sunk? Or have generations of grass caused the soil to build up higher? If the sidewalk is actually level with what it's connected to at the ends, I'd consider regrading the yard.
posted by under_petticoat_rule at 6:31 AM on March 14

I'm not sure how it ended up like this. The sidewalk seems to have stayed the same, as it's at the same level as the concrete around the back porch. But the yard is higher, as is the concrete parking pad near the alley. Regrading isn't really an option because it would only solve half of the problem, as my neighbor's yard is also higher and a lot of the meltwater is coming from his side.
posted by goatdog at 7:37 AM on March 14

FWIW our house (built in the mid 1950s) had a cement front porch that settled. It settled quite a bit, maybe 1.5 feet?

Somewhere in maybe the 1970s or 80s they poured another slab on top to make up the difference. So it is pretty thick, a foot?

Anyway, that has sunk now, too - to about the same level the original porch had sunk by 1985 or whatever.

One reason is that a double-triple thick concrete slab is heavy. Super heavy, astoundingly heavy.

So if it is prone to subsidence now, it will probably be even more so after doubling (or more) the concrete thickness.

However, as you will note from above, even if this is true it is likely to be fine for 20 or 30 or 40 years.

Anyway, a factor to consider - maybe not the most important one.

I was also going to mention mudjacking or foamjacking or slabjacking (or whatever they call it, concrete lifting in general, example) as an option to explore. I don't know enough about to know the cost or whether it will even work in your case, but it is probably worth getting an estimate or two, anyway.
posted by flug at 2:39 PM on March 14