A 700 sq ft Seattle basement, mid-remodel and patched with old residue, was ground and coated in Slate hybrid terrazzo flake with Certified Penntek polyurea.
Not every floor we coat has a car parked on it. This one is the lower level of a modern Seattle home: open-tread stairs, a steel post, a wall of windows and a glass slider out to the yard. The house was mid-remodel, and the bare concrete underneath was a patchwork of old residue, gray skim coat and bare spots. The owner wanted a finished floor that matched the clean lines of the rest of the house, without laying carpet or tile over a slab.
At the end of September 2025 our crew installed a basement floor coating in Seattle: 700 square feet of Certified Penntek polyurea in Slate, a darker hybrid terrazzo flake with a high gloss finish that catches the light from those windows.
We first walked the space in early August 2025. Tools and tarps were everywhere, wiring hung from an open wall and plywood protected the new stair treads. Under all of it, the concrete showed every past project, from old adhesive patches to filler around the edges.
We took moisture readings across the slab at that visit, with one reading of 4.1% on the meter. On a below-grade floor that number matters more than anywhere else in the house, so we check it before quoting. The concrete itself was rated in good condition. Air temperature on install day was 70°F.
A basement mid-remodel is a different job from a garage. Walls are painted, stairs are finished and there is no big door to roll equipment through. The crew masked the stair stringers and walls and protected the new treads before starting.
The result runs continuous from the foot of the stairs to the slider, with no transition strips and no grout lines. You can see the full sequence on our installation process page.
Slate is part of the hybrid terrazzo flake lineup. Up close it reads as a dense mix of charcoal, gray and small white chips. From the stairs it looks like a polished stone floor. With sage walls, dark steel and pale wood treads, it grounds the room without making it feel dark.
That big window wall is also why the topcoat matters. Sunlight is what turns typical epoxy yellow over time. FadeLock™ passed a 16-hour QUV accelerated UV test, and the flake is UV stable, so the floor by the slider should look the same as the floor under the stairs years from now.
Basements are where coatings get tested by water vapor coming up through the slab. A film that just sits on top can blister and peel. Penntek polyurea forms a chemical bond with the concrete at over 1,300 PSI. Before the coating comes up, the concrete will come up.
If moisture readings had called for it, a two-layer moisture barrier system would have gone down first. Our guide to basement floor coatings in Seattle explains how we decide.
The floor carries a limited lifetime warranty backed by Penntek, the manufacturer, and it is registered on every job.
Plenty of Seattle homes are built into hillsides, which puts a lot of living space on concrete. A coated slab is a practical way to finish that space. It handles spills, muddy shoes from the yard and the damp months without swelling or staining like carpet or wood can.
See our Seattle concrete floor coatings page for more, or look at a Seattle garage converted into an office with a Fieldstone floor, another interior job.
Yes. We protect finished stairs, walls and trim before grinding, and the crew vacuums as they go. It helps to schedule the floor after drywall and paint but before baseboards and furniture go in.
Not always. We take moisture readings at the free consultation and decide from the numbers. When a slab needs it, a two-layer moisture barrier goes down under the polyurea basecoat.
The flake broadcast leaves a light texture under the topcoat, so it is not like a smooth painted floor. We do not publish slip ratings, so ask us to bring a sample to your consult and feel it for yourself.
Have a lower level waiting on a real floor? Book a free in-home quote or call 425-226-6085. Sheldon runs installs and will plan the job around your remodel schedule.
Here's just a few of our previous projects.
