Case file — Manassas, VA (near Balls Ford Rd, just off I-66). One of 79 projects we completed across the DMV in 2025. New here? Start with our open letter.
| Location | Manassas, VA (near Balls Ford Rd, just off I-66) |
| Foundation | CMU (concrete block) · a very large basement |
| The problem | Mold and water staining in three corners, water coming through the walls and up from the footing; a step crack in one corner |
| Real cause | A high water table forcing water up from below and in through the block walls — hydrostatic pressure |
| The fix | Heavy-duty interior French drain (FootingShield™) with staged slab cutting and structural slab reinforcement, dual sump pumps, and a wall vapor barrier; mold-damaged framing replaced |
| Warranty | Written lifetime warranty (interior) |
What the homeowner saw
This Manassas home, just off I-66 near Balls Ford Road, has a very large basement — and three of its corners were covered in mold and water staining. The kind of damp, musty space you stop using because something clearly isn’t right down there.
What we found
The driver here was a high water table. Water was coming in two ways at once: up from the footing under pressure, and straight through the CMU (block) walls. Three corners showed mold and staining, and one corner had a step crack in the block. The moisture had been there long enough to reach the framing — some of the wood had started to mold.
With this much water sitting under the slab, the job needed more than a standard trench. Cut the whole perimeter open at once and the floor can settle. The fix had to relieve the pressure and capture the water deep — without compromising the slab.
What we did
This was our interior system — FootingShield™ — built for a high-water-table basement. Every step was done by our own crews, no subcontractors.
- Cut the drywall back to the grade line and replaced the mold-damaged framing lumber.
- Opened the perimeter trench in stages. Because there was so much water below, we left 2 ft of slab uncut every 6 ft so the floor couldn’t settle while the trench was open. Keeping the slab seated was the part we watched most closely.
- Set the drain pipe deep, wrapped it in geotextile fabric, and bedded it in clean gravel.
- Installed drain board and a wall vapor barrier.
- Rebuilt the slab stronger than before — reinforcing rebar doweled into the existing slab with epoxy, then new concrete poured over it.
- Placed two separate sump pumps in two corners to move the volume of water this basement produces.
The result
A very large basement that had water on three corners and mold creeping into the framing was dried out, reinforced, and protected — with a slab that’s now stronger than it was before we started.
The takeaway
When the water table is this high, you can’t just trench the whole perimeter at once — the slab can settle into the water below. Staged cutting, a deep drain, structural slab reinforcement, and enough pumping capacity (two sumps, not one) are what keep a big, wet basement dry and sound.
Water or mold in your Manassas basement? Schedule a free inspection — we’ll find exactly how the water is getting in and tell you honestly what it takes to stop it. Learn more about our interior French drain & sump pump systems and mold removal.
FAQ
Why leave parts of the slab uncut when installing an interior drain?
When the water table is very high, removing the entire perimeter slab at once can let the floor settle. Cutting in stages — leaving short uncut sections — keeps the slab supported while the drain goes in. The slab is then reinforced and re-poured, so it ends up stronger than before.
Written by S. Altan Atasoy — civil engineer (University of the District of Columbia), a member of the American Society of Civil Engineers, and MHIC-licensed in Maryland (#165773) — in the field since 2005.
