Water is the most expensive thing that ever gets into a building. OAK Builders' dedicated commercial waterproofing division finds it, stops it, and keeps it out — from foundation to parapet — across Washington, DC, Maryland, and Northern Virginia.
OAK Builders LLC · Falls Church, VA 22044 · Serving all four DC quadrants, MD & NoVA · (826) CALL-OAK / 826-225-5625 · info@oakcgc.com
Washington's buildings are aging into exactly the problems we know best. The District's stock runs from 1920s load-bearing masonry rowhouses converted to offices and condos, to mid-century concrete institutional buildings, to Class A towers sitting on multiple levels of below-grade parking — often with occupied plazas, vaults, and areaways pushing right to the property line. Each fails in its own way: saturated brick and stone, failed below-grade membranes under decades of hydrostatic pressure, leaking plaza decks over lobbies and garages, and sealant joints decades past their service life.
Commercial waterproofing here is now a core OAK Builders service line — not a trade we broker out, but work we assess, design, and self-perform. It's a natural path for us: our principal managed building-envelope rehabilitation programs on the owner's side — exterior stone restoration and repointing at the National Building Museum, a building envelope study for OPM headquarters, and three phases of VDOT building-envelope rehabilitation. Our team includes a licensed structural engineer, so diagnosis and repair design carry a PE's judgment, not a salesman's.
Most water intrusion drags on because the investigator, the designer, and the installer are three different companies pointing at each other. At OAK they're one contract: we find the source, engineer the fix, install it, and water-test it before we call it done. If you're not ready for repairs and just need answers, start with a standalone water intrusion assessment — and where moisture has already attacked structure, our structural assessment & repair team is the same phone call.
Foundation membranes (hot/cold fluid-applied and sheet), bentonite systems, blindside waterproofing, and crystalline treatments for new and existing structures.
Drainage board, footing drains, French drains, sump systems, and site grading corrections that move water away from the structure for good.
Vehicular and pedestrian traffic coatings, hot rubberized asphalt assemblies, and split-slab waterproofing for plazas, terraces, balconies, and parking structures.
Joint sealant replacement, penetrating masonry water repellents, and elastomeric coatings that stop wind-driven rain at the wall.
Cutting and repointing deteriorated mortar joints, brick and stone replacement, and lintel repairs — preservation-grade where the building demands it.
Building expansion joint systems, precompressed foam joints, and full recaulking programs with documented adhesion testing.
Base flashings, counterflashings, coping, through-wall flashing, and roof-to-wall transitions — where most 'roof leaks' actually live.
Negative-side crystalline systems, interior drainage channels, and vapor mitigation where positive-side access isn't feasible.
Our crews work across all of Washington: NW, NE, SE, and SW — downtown and the Golden Triangle, Georgetown, Capitol Hill, Foggy Bottom, NoMa, Navy Yard, and the Southwest Waterfront. The same commercial waterproofing division covers the Maryland and Northern Virginia suburbs, with dedicated service pages for the markets we're in most:
Arlington, VA → Alexandria, VA → Fairfax, VA → Bethesda, MD →
A large share of DC's commercial waterproofing work sits inside historic districts — Georgetown, Capitol Hill, Dupont Circle, Shaw, and dozens more — where exterior repairs to street-facing façades can require Historic Preservation Review Board (HPRB) or Old Georgetown Board concurrence before the Department of Buildings issues a permit. Repointing mortar must match the original in composition and profile; sealant and coating choices are constrained; and cleaning methods are regulated. We build that review into the schedule instead of discovering it mid-project.
Below grade, many downtown buildings extend under the sidewalk into vaults and areaways in public space — which brings DDOT public-space permitting into play alongside the DOB permit. Our estimates identify which approvals your scope actually triggers, who obtains them, and how long they realistically take.
Condominiums & HOAs. Plaza decks over garages, balcony coatings, façade sealants, and below-grade garage leaks — engineered fixes with the documentation boards need for reserve planning. Boards that want independent oversight of a larger envelope program can also engage our separate owner's representation service.
Office & mixed-use. Occupied-building phasing, night and weekend work, and protection plans that keep tenants dry and open while we work.
Federal & institutional. Envelope rehabilitation experience at landmark federal buildings, SAM.gov-active (UEI YM3RMQHPMTF8, CAGE 125C2), and comfortable with badged, secure-facility logistics.
Parking structures. Vehicular traffic coatings, expansion joints, and drainage corrections that stop chloride-laden water before it reaches reinforcing steel.
A leak isn't fixed until it's reproduced, traced, repaired, and water-tested. That's the path every OAK waterproofing project follows.
Moisture survey and leak history review — non-destructive first: infrared, moisture metering, visual survey of the full envelope.
Controlled water testing to reproduce the leak and isolate the true source — not just the symptom stain.
A PE-backed repair design with materials, details, and phasing matched to your building — and a line-item budget.
Execution by our crews with manufacturer-certified installers where warranties require it, protected and phased for occupied buildings.
Post-repair water testing to prove the fix before we leave — documented and photographed.
Written workmanship warranty, manufacturer system warranties where applicable, and an annual envelope maintenance option.
It depends on system and access far more than square footage alone. Published industry guides put below-grade remediation and plaza deck recoating anywhere from a few dollars to well over twenty dollars per square foot depending on excavation, demolition, and the assembly specified — which is why we start with an assessment and give you a line-item budget for your building, not a blended rate.
Often, yes. Structural repairs, excavation, and work in public space typically need DC Department of Buildings permits, and street-facing façade work in historic districts can require HPRB or Old Georgetown Board review first. Vaults and areaways under sidewalks add DDOT public-space permits. Our proposals identify exactly which approvals your scope triggers.
Yes — most of our work is in occupied buildings. Phasing, protection, negative-air containment where needed, and off-hours scheduling are built into the plan and the price, not treated as change orders.
Controlled water testing — before repairs to reproduce and isolate the source, and after repairs to prove the fix. Both rounds are documented and photographed, and the repair carries a written workmanship warranty plus manufacturer system warranties where applicable.
Freeze-thaw cycling over winter opens up failed joints and membrane seams, and spring rain finds them. We wrote a full explainer: why plaza decks leak every spring — and how to fix them for good.
Call before the damage compounds — assessment scheduled within days, report with real budget numbers, repair by the same team.