A large Mercer Island garage with steel posts, glass doors and side closets got a 1/4 inch Rhino Grey flake floor in Certified Penntek polyurea in October 2026.
Mercer Island homes tend to stack living space on steep lots, and the garage often ends up as a big lower level with more going on than parking. This one has a row of four glass-panel garage doors, steel support posts, heavy wood beams overhead and a string of closets and storage rooms along the back wall. The concrete underneath was gray, dusty and patched, with chalky spots and old stains in the corners.
In early October 2026 our crew installed a garage floor coating on Mercer Island with Certified Penntek polyurea in Rhino Grey, using 1/4 inch flake. The main garage and the side rooms all got the same finish.
The free consultation was in mid-September 2026. A garage this size gets tested in more than one place, because slabs are rarely uniform from front to back. Our meter read 4.3%, 4.7% and 2.7% at three spots. We also ran a scratch test with a hardness pick to see how hard the surface was before choosing the grinding setup.
Other things we noted:
With the side rooms and posts, this one took two days at the start of October.
The coating runs right up to the base of each post and through every closet doorway, so the whole level reads as one floor.
Rhino Grey is a mid-gray flake blend with darker and lighter chips. With white walls, dark beams and black-framed glass doors, it looks clean and modern without feeling cold. Those glass doors also let daylight in, which is why the UV-stable topcoat matters here. Typical epoxy ambers in sunlight. FadeLock™ passed a 16-hour QUV accelerated UV test, so the gray stays gray.
Browse similar options on our styles and colors page.
A garage like this is part of the house. Nobody wants to redo it in five years. Penntek polyurea bonds chemically to the concrete at over 1,300 PSI, and the polyaspartic topcoat resists hot tire pickup. Typical epoxy often starts to peel in years 3–5. A Penntek floor is built as a 30–40 year floor.
The warranty is registered with Penntek, the manufacturer, on every job. Penntek has dealers in 200 markets, so the floor can be serviced even if any one installer is gone. Our post on how long a Penntek floor lasts goes deeper, and the Penntek Hammer Test shows what the surface can take.
Mercer Island sits in the middle of Lake Washington, and many homes are built into slopes with garages at the lowest level. Those slabs sit against the hillside and can carry more moisture than a garage on flat ground. That is why we take several readings, and why a two-layer moisture barrier system is available when a slab needs it. If you are new to the island, the City of Mercer Island site is a good place to start for local info.
Bellevue is just across the bridge. See our garage floor coatings in Bellevue, or look at another Mercer Island garage we coated in Mount Everest.
Yes. As long as the floor is concrete, we can grind and coat it in the same system. Carrying the floor into side rooms makes the whole level look finished.
Readings vary across a slab, especially on a hillside lot. Testing several areas shows us whether any part of the floor needs a moisture barrier before the basecoat.
Many garages are done in one day. Larger floors with posts and side rooms, like this one, can take two. We give you the schedule at the consult.
Ready to finish your lower level? Book a free in-home quote or call 425-226-6085.
Here's just a few of our previous projects.
