Paver Installation in Sammamish

Occasionally, and that is enough. This is not a climate with months of deep frozen ground, so the dramatic heave seen in genuinely cold regions does not happen here. What does happen is a handful of freeze events each winter acting on ground that is thoroughly saturated, because it always is by then. A few small lifts a year, over a decade, produce a surface noticeably out of level with no single event to blame it on. The reason to build free-draining is not that a hard freeze is coming — it is that the cost of being wrong is a surface you eventually lift, and the cost of being right is a slightly better grade of rock.

Base material with the fine particles washed or screened out of it, so the spaces between the stones stay open and water moves through rather than being held. In practice that means a specified clean angular crushed rock rather than a general fill or a cheaper pit-run material that arrives with sand and silt through it. Angular matters as much as clean: crushed faces lock together under compaction where rounded stone rolls, so a clean angular rock compacts to a stable, load-bearing, still-porous layer. It is worth asking the question by name, because both materials look broadly similar to anyone who is not looking for the difference.

Usually because the edge restraint has given way and the field is creeping outward, and freeze cycles accelerate it. Every unit is held by friction against its neighbours and ultimately by whatever restrains the perimeter — and once that restraint fails, small seasonal movements accumulate outward rather than returning. Wider joints then let more water into the base, which makes the next cycle worse. The fix is to reinstate a proper restraint at the perimeter and re-joint the field, and where the movement has been going on for years, lifting and resetting the outer courses back to their original line.

More than most people want, and it is worth arguing about at design stage rather than living with it afterwards. A surface laid genuinely level does not shed water — it holds a thin film across it after every rainfall, which in a shaded winter garden simply stays there, grows algae and freezes. A modest fall is imperceptible underfoot, does not affect furniture, and is the difference between a surface that dries between rainfalls and one that does not. The important part is not the number but the direction: away from the house, toward somewhere the water is entitled to go, and settled before the base is built.