Pittsburgh ground is clay over layers of shale and sandstone, tilted into steep hills and cut by small streams the locals call runs. Most concrete failures here start with where the water goes.
Do I need to worry about drainage?
Yes, more than anything else. Drainage decides whether a slab survives winter here. Water that sits on concrete freezes and scales it. Water that sits under it freezes and lifts it. Every slab should slope to a place where water can leave, and downspouts should discharge beyond the concrete, not onto it.
My patio or driveway slopes toward the house. Can that be fixed?
Yes, though the fix depends on how much fall is wrong. A slab that slopes toward the house or garage sends meltwater to the foundation, and on Pittsburgh hillside lots the driveway often has no choice but to run downhill to a garage door. In that case a trench drain across the bottom, piped to daylight or a proper outlet, is the normal answer. A patio that has tipped back can sometimes be lifted. One that was formed wrong is replaced.
Can tree roots crack or lift concrete? Can I fix the concrete and keep the tree?
Tree roots can lift a panel several inches and crack it in half. You can usually fix the concrete and keep the tree. Options include grinding the lip, replacing the panel with a slight ramp over the root, or curving the walk away from the trunk. Cutting a large root close to the trunk risks killing the tree or making it unstable, so we ask an arborist before any big root is touched. A street tree belongs to the municipality, and its roots are not yours to cut without asking.
My neighbor's new concrete sends runoff onto my property. What can I do?
Talk to the neighbor first and show them where the runoff goes during rain. Often a downspout extension or a small swale solves it. If that fails, your municipality's code office can say whether a grading or stormwater rule has been broken, and a lawyer can advise on your rights. On steep streets a small change uphill can send a lot of water downhill. This is general information, not legal advice.
Does clay or soft soil change the job?
Yes. Clay holds water and drains slowly, so it heaves in winter and turns soft in spring. On clay we dig deeper, lay fabric where needed and build up a thicker layer of compacted crushed stone. The region is also known for a slippery clay layer called the Pittsburgh red beds, which is linked to hillside slides when it gets saturated. If a slope shows fresh cracks, leaning trees or bulging at its toe, it needs a geotechnical engineer before any concrete.
My gravel driveway turns to mud. Is concrete the answer?
It can be, once the water problem is dealt with. A gravel driveway turns to mud when stone gets pushed down into wet clay. Concrete over that same mud will crack. The muck is dug out, fabric and clean stone go in and get compacted, and then the slab is poured. On a steep drive, concrete also ends the yearly job of raking washed-out gravel back up the hill.
My patio was poured over an old trench and it settled. Why?
Because the trench was backfilled loose. Any trench for a sewer, water or gas line, and the dug-out zone around a foundation, keeps settling for years unless the fill was compacted in layers. A patio poured across it sinks along that line. The lasting repair is to remove the panel, compact or replace the fill and repour. Lifting can work when the settling has finished.
What should I know about a raised patio or slab in a flood-prone area?
Check the flood map first. Low ground along the rivers and along runs such as Saw Mill Run, Pine Creek and Girty's Run can flood, and building or filling in a mapped floodplain needs approval from the municipality. A raised patio or slab there must not block the flow of water or push it onto a neighbor. Use air-entrained concrete, keep finishes simple and expect to wash silt off after high water.
Could old coal mines under my lot affect concrete?
They could. Parts of Allegheny County sit over abandoned coal workings, and ground above them can sink. Pennsylvania's Department of Environmental Protection says damage from mine subsidence is usually not covered by a homeowner's policy, and it offers Mine Subsidence Insurance directly. A slab that drops suddenly with no water cause is worth reporting before it is simply replaced.
For a real number, we need to see the site. Call (412) 725-2024 or text a few photos, and we will set up a free on-site estimate with a written quote.