Paver Patios in Sammamish, WA

Yes, and it is the single most important decision on a Sammamish patio. Level ground over glacial till has nowhere to shed surface water to and passes almost none downward, so the base build-up under your patio spends much of the winter surrounded by saturated soil. Water in a base washes fines out of the compacted rock and hollows it, and the surface follows. The specification that works here is a genuinely free-draining base with a drainage layer and a real outfall taking water away from the footprint — not simply a deeper layer of the same material.

By dividing it rather than maximising it. On a quarter-acre lot the instinct is one large terrace, and the result frequently reads as hard standing and gets used at one end. Two or three related areas work far better: a dining terrace sized properly for the table plus circulation behind the chairs, a separate seating or fire area, and planting or a level change between them. It costs the same per square foot, and it gives a garden this size something it usually lacks, which is a reason to walk from one part of it to another.

Establish what it is before designing around it. The plateau carries genuine wetland and seasonally saturated ground scattered through it, some of it regulated as a critical area with rules on what can be built and how close. Several of these look entirely ordinary in July. If part of your garden behaves differently through the winter, that needs identifying properly rather than being drained and paved over. Where the ground is simply wet rather than regulated, the answer is a deeper free-draining base and a drainage route out from under the footprint.

Sometimes, and Sammamish associations reach further than most. Klahanie, Trossachs, Sahalee and the newer developments commonly have architectural standards covering hard surface materials and appearance, and while a fully screened rear terrace is often outside the remit, anything visible from a street or a shared space usually is not. It is a scheduling item rather than an obstacle. We ask on the first visit, and where review applies we produce dimensioned layouts and material samples in a form that can go to a board without being redrawn.