Concrete Overlays in Mercer Island, WA

Concrete overlays in Mercer Island: what to know

The city’s housing element counted 2,783 homes built before 1959 and 3,966 more from 1960 through 1979, against 1,655 from 1980 to March 2000. That leaves many mid-century driveways and patios whose surface is tired but whose base may be fine. What decides the job is whether the slab has moved. A crack that widens each wet season, or a corner that tilts on a sloped lot, will show through any coating.

An overlay keeps the footprint, so it adds nothing to lot coverage or the 9 percent hardscape allowance. Rinse water is the local concern. Drainage reports for island lots trace runoff through city storm pipes to Lake Washington, so slurry and wash water stay on the lot.

Permits and rules in Mercer Island

A private-slab overlay leaves the footprint and grade as they are, and the city’s exemption list never mentions resurfacing. The standard exemptions do not apply inside a mapped critical area. The apron belongs to the public right-of-way, which has its own permit. Before we quote, we check with Community Planning and Development on how a surface coat on your slab is treated and whether the hazard map changes the answer.

Rules change and vary by parcel, so we confirm the current requirements with the city before we start.

How we approach it

Look for cracks that open and close with the wet season before overlaying
Keep slurry and wash water out of catch basins that drain to the lake
Hold the buildup thin at garage doors so water still drains away from them
Leave the footprint alone so lot coverage and hardscape totals stay unchanged

For the full process, see our Concrete Overlays page.

Building in the cold months? See our guide to winter concrete pours.

Our concrete overlays work, serving Mercer Island

Examples of our work. We build concrete overlays in Mercer Island and the cities around it. See all of our work

Questions from Mercer Island homeowners

Can an older Mercer Island driveway be resurfaced instead of replaced?

If the concrete is stable, usually yes. Worn surface, stains, and shallow spalls are what an overlay fixes. A slab that has tilted or sunk on a sloped lot is moving, and that section is replaced and its base rebuilt before any overlay goes on.

Does resurfacing change my Mercer Island lot coverage?

No, because an overlay sits on the existing slab. Lot coverage counts buildings plus vehicle surfaces by area, and patios fall under the separate 9 percent hardscape allowance. Widening while resurfacing is a different job, since it adds area. We price and permit the two separately.

Where does overlay wash water go on Mercer Island?

Not into the street drain. Drainage reports for island lots trace storm pipes to Lake Washington, and the city’s permit conditions make the owner responsible for controlling runoff from impervious areas. We collect slurry, sealer, and rinse water on the lot.