We built SGP Waterproofing around one idea: a homeowner or property manager in Kent, WA shouldn't have to wait three days for someone to look at a wet wall.

SGP Waterproofing is a licensed and insured Waterproofing contractor serving homeowners, property managers, and commercial building owners across Kent, WA. We didn't start as a marketing company that added waterproofing to a service list — our crews came up running sump pumps, pouring interior drain tile, and injecting epoxy into foundation cracks long before the trucks had our name on the door.
We keep our crews local rather than routing calls through a national call center, which means the technician who answers your questions on the phone is often the same person standing in your basement two hours later. That continuity cuts down on the miscommunication that drags out so many waterproofing jobs.
Soil composition changes how much hydrostatic pressure builds against a foundation wall, and Kent, WA's mix of clay-heavy and sandy soils behaves differently depending on the neighborhood, sometimes block to block. A crew that hasn't worked the area tends to size drainage systems using generic assumptions instead of what's actually under the yard.
We also see a lot of properties where a previous waterproofing attempt only addressed the symptom — a topical sealant painted over a cracked wall, for example — without solving the pressure or grading issue causing the crack in the first place. Part of every Kent, WA inspection is checking for that kind of prior patch job before we recommend anything new.

Most Kent, WA water intrusion problems don't start as a flood — they start small, and they get worse on a schedule. Here's what our technicians look for on a first inspection.
That damp, earthy smell in a finished or unfinished basement is usually mold or mildew feeding on moisture that's already gotten past your walls.
Efflorescence forms when water carries dissolved minerals through porous concrete and leaves them on the surface as it dries — a clear sign moisture is actively passing through.
A crack that's a sixteenth of an inch wide today can become a sixteenth of an inch wider by next spring if the pressure behind the wall isn't relieved.
Drywall that feels soft, bubbles, or shows a tide line near the floor is already absorbing groundwater — by the time you see it, the insulation behind it is usually soaked too.
If your window wells hold water for more than an hour after a storm, that water has nowhere to go but toward the seal around your basement window.
Water that pools against your foundation after every rain is telling you the drainage system, whatever's left of it, has stopped doing its job.
We scope every Kent, WA job in person before quoting it, because two houses with the same symptom rarely need the same fix. These are the five services that make up most of our workload.
A burst window well seal or a failed check valve can put inches of water in a basement in under an hour — our emergency crews carry truck-mounted extraction pumps and moisture meters to start mitigation the same day you call.
For finished basements we route the drain tile beneath the existing slab edge, which limits how much flooring has to come up during installation.
We coordinate directly with building engineers and HOA boards so the scope, timeline, and access requirements are agreed on before a crew ever shows up on-site.
Crack injection is often the most cost-effective Kent, WA repair when the crack is isolated and the wall itself hasn't bowed or shifted.
We install heavy-gauge vapor barriers, seal foundation vents, and add a dedicated sump basin so a damp Kent, WA crawl space stops feeding moisture into the floor joists above it.
Extending downspouts another six to ten feet away from the foundation solves more Kent, WA drainage problems than people expect, and we'll usually check that before recommending anything more invasive.
A dispatcher walks through symptoms with you on the phone so the crew that shows up already has a rough idea what they're dealing with.
A technician maps moisture readings, checks grading, and identifies whether the source is groundwater, surface water, or condensation.
We put the scope, materials, and price in writing so you can compare it against anyone else's estimate line for line.
Once installation wraps, we test the sump pump under load and walk you through the warranty paperwork before we leave the site.
We quote the whole job as one flat number, so the price on the invoice matches the price we quoted on day one.
Same-day availability isn't guaranteed on every job, but our Kent, WA dispatch is built to prioritize it whenever the situation calls for it.
Every technician trains on interior drain tile installation, sump system sizing, and crack classification before they lead a job on their own.
If a sealed crack reopens or a sump system underperforms within the warranty window, we come back and make it right at no extra charge.

We document every job with photos, moisture readings, and a copy of the warranty terms, so there's a paper trail if you ever need to reference the work again.


Our Kent coverage area extends through most of the surrounding Kent, WA communities. Give us a call even if your address falls just outside the zone below; we'll let you know honestly if we can reach you same-day.

Zip codes we serve in Kent, WA: 98031 98030 98032 98042 98035 98064 98089

"We had water coming in around the window well every time it rained hard. They regraded the area and sealed the well, and we haven't had a drop since."
— Kent Homeowner
"The crack in our basement wall had been leaking for a year before we finally called. Injection took less than an afternoon and it's been dry since."
— Kent Seller
"The crawl space under our addition never dried out properly. Full encapsulation with a dehumidifier fixed it in one visit."
— Kent Homeowner
"Sump pump failed overnight and flooded part of our storage room. New pump was installed with a backup battery the same afternoon we called."
— Kent Customer
"Our parking garage had a persistent leak coming through the deck above the lower level. They installed a membrane system and coordinated the work around tenant parking so nobody was displaced."
— Kent Property Manager
"They found the actual source of the dampness instead of just recommending a dehumidifier and calling it done. Been dry for over a year now."
— Kent Homeowner
Most Kent, WA emergency calls get a technician on-site within a few hours; non-urgent inspections are typically scheduled within one to two business days.
Yes — every job gets a flat-rate, written quote before work begins, and that number doesn't change once the crew is on-site.
We handle active flooding, sump pump failures, and failed foundation walls with same-day dispatch, portable extraction pumps, and temporary water mitigation.
Cost depends on square footage, the type of system needed, and whether the fix is interior drainage, exterior membrane work, or both — we won't quote a number without an in-person inspection first.
Hairline cracks are actually the ideal time to call, since injection repair is faster and cheaper before hydrostatic pressure has a chance to widen the gap.
We install both — interior drain tile and sump systems for most residential jobs, and exterior membrane or French drain systems when the source is surface water or when excavation is practical.
We give you a realistic timeline in the written quote so you can plan around the crew being on-site.
Documentation from our inspection often helps speed up the claims process, but final approval is always the insurer's call.
A French drain without a sump pump just relocates water to one spot; the pump is what actually discharges it away from the home.
Yes, every interior drainage, sump, and crack repair job comes with a written warranty, and terms are explained in full before you approve the quote.
Standing water doesn't stop us from starting; we extract it as the first step, then proceed with vapor barrier and drainage installation.
Yes — our commercial work covers parking garages, retail basements, and multi-family buildings, usually scheduled in phases to minimize tenant disruption.
One call gets you a licensed technician, a written quote, and a same-day time window.
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