Mercer Island sits in the middle of Lake Washington, so almost every street runs downhill to the water. Lots are steep, the tree canopy is old and tall, and the shoreline lots have banks that move when runoff from the street above has nowhere else to go. A solid patio pitched down the bank is a roof you added over the shore. We break that run with a drain, a bed, or a permeable field.
King County · ZIP 98040
Pavers that do not shed into the lake
The patio itself is built like any wet-climate patio: deep base, pitch off the house, tight edges. The grade beyond it is the lake problem. We do not send the wash straight down a dirt bank.
Joint sand and fines are part of what washes. We lock the joints and we keep a planted edge that can catch what the rain moves. A patio to the water, with bare soil under it, is a job we redesign before we build it.
The ground in Mercer Island
Most of our work here is on slopes. A patio or terrace has to be cut into the hill with a real base and a drain behind any wall, or the first wet winter shows where the water wants to go. On the lakefront lots we keep native shrubs on the bank, because they hold the soil better than lawn, and we take runoff to a drain or a rain garden instead of letting it sheet over the edge.
The city is strict about removing large trees and about work near the shoreline. We check what needs a permit before we cut or dig, and we plan around the trees you have to keep. Under those firs and cedars the ground is shady and mossy, so we often turn worn-out lawn into planting beds and stone paths that stay clean year-round.
How we do the work
The paver is the skin. The base is the job: excavated, built up in compacted rock, deep enough that this climate will not heave it into waves. We pitch the surface away from the house, we restrain the edges so the field cannot spread, and we sand the joints.
A paver patio set on a couple of inches of loose gravel over clay will look perfect in September and rock underfoot by March. We do not build that, even if the other bid did.
What we look at first
- How the water leaves the surface today
- Clay, fill, or roots under the area
- Edge restraint and where the field ends
- Whether the project is a walk, a patio, or a drive, because the base changes
Joint sand
Swept and settled, then checked. Polymeric sand has a place where ants and heavy rain empty the joints, and it has a failure mode if it is installed wet or left on the face. We use it when it helps, and we wash the haze off before we leave.
Edges
Plastic or metal restraint, spiked into the compacted base, then buried so you see paver, not a black strip. An edge against soil with no restraint is the row that opens up.
The base depth
Deeper for a drive than for a walk, and deeper on clay than the brochure drawn for a dry state. We compact in lifts. A single dumped pile of gravel, raked once, is not a base. You should not see waves after the first winter.
More from this crew
- Paver installation across the region
- Patio installation in Mercer Island
- Hardscaping in Mercer Island
- Gravel installation in Mercer Island
- Pressure washing in Mercer Island
- Paver installation in Sammamish
Sources for the climate and the water
- USDA plant hardiness map for choosing plants that can take a King County winter.
- EPA WaterSense on watering less once a lawn or a new planting is established.
- EPA Soak Up the Rain on keeping roof and yard water from becoming someone else’s problem.
