Landscaping in Laurelhurst, Seattle

Often yes, but not by excavating a conventional base through the root zone. The roots that keep a large tree alive are mostly in the top eighteen inches of soil and extend well beyond the branch spread, so a standard six to eight inch excavation across that area severs a substantial share of them. The alternatives are a shallower build-up, a surface floated over the root zone on a suspended or permeable system, or shifting the layout so the hard surface sits outside the critical root area. Each has trade-offs and we will explain them. What we will not do is dig it out and tell you the tree will be fine.

Because size does not help when the subsoil is till. Under most of the neighbourhood is a dense hardpan that water passes through very slowly, and it is covered by only a foot or two of good topsoil. Through summer you would never know. From October the rain arrives faster than the topsoil can move it sideways, it saturates, and the surplus sits on the surface — and a large flat lawn has nowhere for it to run to. Aeration and reseeding do nothing about this. The fix is a drain routed to a real discharge point, sometimes combined with a slight regrade so the ground itself moves water away from the house.

The whole thing, even if only part of it gets built. On a lot this size the expensive mistake is building three good areas at three different times that do not relate to each other, and then discovering the route between them was never planned. A full design costs a fraction of the build and lets you stage it sensibly — with the critical rule that everything buried goes in during the first stage. Drainage, irrigation sleeves and lighting conduit are cheap while the ground is open and expensive once there is a finished patio over them. Structure first, surfaces second, planting and lighting last is the sequence that works.

Very possibly, and it should be established before anything is scheduled. Seattle regulates tree removal on private property with additional protection for larger and designated exceptional trees, and several of the species common on these lots reach that threshold comfortably. Removing a protected tree without approval carries real penalties. There is also a practical argument for asking a second question first: a mature conifer moves a substantial volume of water out of the ground through the growing season, so taking one out of a garden that already drains poorly can make the winter worse. We look at both before recommending removal.