Basement Waterproofing, Foundation Repair & Crawl Space Encapsulation in Alexandria, VA

A damp line along the bottom of the wall, chalky white bloom on the block, water creeping across the floor after a hard storm. Most of Rosemont was built with a basement under it, and this is what they do when the ground outside holds water. Pressure builds against the wall and it comes in wherever the wall is weakest, which is why patching the spot you can see never holds for long.

Instead of fighting that pressure we give the water somewhere to go. An interior drain goes in around the edge of the floor, perforated pipe bedded in washed stone below the slab, running to a pit where a pump sends it clear of the house. The stone has to be washed, or fine grit works into the pipe and blocks it inside a season.

Not every basement needs all that. Where the yard slopes toward the house, as it does on plenty of Del Ray lots, regrading is a smaller job and sometimes the whole fix. Sealing one active crack can be enough on its own. It does nothing for a burst pipe and will not fix condensation.

A door you have to shoulder shut, a crack above a doorway, brick outside cracked in a stair-step pattern. The question people ask first is whether it is serious or whether it can wait. In Alexandria it usually comes back to one part of the footing sitting lower than the rest, and on the Rosemont houses, which average 1954, a lot of that settling finished decades ago.

How we fix it depends on what moved. If the footing sank, we drive steel piers down to solid ground and move the weight of the house onto them. If a wall is leaning in, we brace it. If the house settled long ago and then stopped, we seal what it left behind and leave the rest alone.

If a corner has dropped enough that you can see it across a doorway, we can usually lift it back, over several days so the plaster upstairs does not crack, which matters more in the older Old Town houses than anywhere else in the city. None of it dries the ground out. If the footing sank because the soil stays wet, we handle that in the same job.

A musty smell that meets you at the door, floors that feel cold in January, humidity upstairs that will not come down whatever the thermostat says. All of it starts under the house. Where a Taylor Run home sits over a crawl space rather than a basement, that floor is usually bare dirt, and bare dirt gives off water all day long.

Encapsulation covers that ground. A heavy liner goes over the whole floor, up the piers and up the walls, taped at the seams and run over the top of the footing so nothing gets in behind it. We close the vents, because summer air here carries in more water than it takes out. Then a dehumidifier sized to the space keeps it dry and drains itself.

This is not a structural repair. A floor that has already dropped needs new supports as well, and a liner laid over standing water only hides the water. Where the space has standing water, as it does on the lower Arlandria lots, drainage goes in first, because sealing over water only traps it under the liner. If your crawl space is already dry and covered, a vapor barrier alone will do.

Water across the floor after a storm, a pump you can hear running constantly, or one you only find has quit because the basement is already wet. Everything else down there collects water and sends it somewhere. The pump is what gets it out of the house, and most people meet theirs on the night it fails.

In the Rosemont basements the pit goes wherever the floor falls to, so the drain lines run into it. The pump sits on a solid base inside the pit rather than down in the silt, which kills more pumps than hard work does. A check valve stops the last few gallons draining back down the pipe. The outlet has to finish well away from the house.

On its own a pump waterproofs nothing. If nothing drains toward the pit it sits dry while the far corner floods. A battery backup covers the power cut that arrives with the storm, and most units last seven or eight years here. On a Del Ray house that has flooded before, a second pump set higher in the pit earns its place, since it only runs when the first falls behind.

A floor that runs downhill across a room, a spot near the middle that gives when you cross it, doors upstairs that have started catching. Something a few feet below has moved. The posts have pressed into ground that was never compacted, the beam has sagged between them, and joists that have breathed damp air for seventy years are not as strong as they were.

We pull the old posts and set adjustable steel ones on new concrete pads, so the weight rests on concrete instead of dirt. The beam comes back to level a little at a time over several days, because lifting it in one afternoon cracks plaster upstairs. Weak joists get new lumber bolted alongside, soft ends are cut back to solid wood, and anything rotted through gets replaced.

Lifting a floor does nothing about why it dropped. Around Northeast, where the ground holds water, the new lumber ends up like the old lumber if the damp stays. We look at both on the same visit and tell you which part needs doing now and which will keep another year. Access shapes the price as much as the work does, and under the Taylor Run houses it is tight.

A strip of lawn still soft three days after rain, ground along one side of the house that never quite dries, a basement that takes water at the same corner every storm. That is water sitting against the house instead of running away from it. On the flatter Potomac Yard ground it has nowhere obvious to go.

We dig a trench above wherever the water keeps arriving. Filter fabric goes in first so silt cannot block the pipe, then perforated pipe on a steady fall, then washed stone packed around it. The water hits the stone, drops into the pipe and runs off. Depth matters more than length, because the pipe has to sit below the level the water is travelling at.

Where the pipe ends matters too. Emptying into ground that is already wet does nothing. This handles groundwater and nothing else. A crawl space damp from humid air is a different job, and regrading the yard is sometimes the cheaper answer, which we will say when it is. Downspouts emptying at the wall get picked up in solid pipe and carried clear, which on the older Rosemont lots is often the whole job.