Cracks repaired, algae ground away, and the covered porch, patio, and wraparound walkway sealed under one continuous Penntek polyurea surface in Flint.
The concrete around this Seattle home had cracks running through several slab sections, moss rooted into the joints, and green algae spreading across everything the sun never reached. The homeowner has spent years building the garden around this space, with potted plants along every edge and a stone fireplace at the corner. The concrete was the one part that had stopped keeping up. Cascade Concrete Coatings brought the certified Penntek polyurea system in Flint across the covered porch, the open patio, and the walkway that wraps the corner of the house.
This slab had two things working against it. Cracks were running through multiple sections, some of them branching, which means water had a direct path into the concrete. And the whole area sits in heavy shade, so what got in stayed in. That is how you end up with moss growing in the joints and green algae across the surface. Shaded concrete in Seattle almost never fully dries out between October and May. Pressure washing knocks the green off for a few months and does nothing about the cracks that let the water in.
Every crack was addressed with Penntek rapid-cure mender before coating, filling and sealing the paths water had been taking into the slab. On concrete with this much cracking, the repair work is the job. The coating is what protects it afterward.
The full surface was ground to strip the algae, the biological staining, and the weathered layer, opening the pores so the coating could bond mechanically to clean concrete.
Slab temperature, air temperature, moisture content, humidity, and dew point were measured and recorded before any product was mixed.
The covered porch, the open patio, and the walkway were all coated as one system with no break at the transitions. The patio here was poured in several sections over the years, and a continuous coating pulls it together into one surface instead of a patchwork.
The base bonds into the open concrete at over 1,300 PSI. Full flake broadcast in Flint gives the surface grip and a blend of tan, grey, and cream chips with scattered darker flake, so it reads closer to natural stone than a uniform color.
The topcoat seals everything into a non-porous surface that rinses clean with a hose.
Epoxy is the wrong product here twice over. It yellows in UV, and it has no meaningful flex, so a slab with existing cracks and seasonal movement pushes it off. Penntek polyurea stays flexible enough to move with the concrete, and the FadeLock UV package keeps Flint from shifting color over time. The part that matters most on a shaded Seattle patio is that the finished surface is non-porous. Moss and algae need something to root into, and a sealed polyurea surface gives them nothing. Water sits on top and rinses away instead of soaking in and feeding whatever is growing there. It also cures in a single day even in cool, damp conditions, which is why this went from cracked and green to finished without the homeowner losing a week of the garden.
This installation carries the Penntek Limited Lifetime Residential Warranty, covering the product and the installation. It is only available through certified Penntek dealers, and Cascade Concrete Coatings is one of them.
Cascade coats patios, walkways, garages, shops, and commercial floors throughout Seattle and the greater Puget Sound area. Shaded north-facing concrete, heavy tree cover, and slabs that never fully dry out are standard conditions here, and the certified Penntek system is built for exactly that. See this Seattle walkway coating project and more Seattle polyurea coating work from the same crew.
If your patio is cracking, going green, or getting slick in the wet months, coating it solves the problem instead of postponing it. Cascade Concrete Coatings serves Seattle and the greater Puget Sound area with free in-home quotes and same-day installs. No pressure, no obligation.
Here's just a few of our previous projects.
