Basement Waterproofing in Sammamish, WA

Basement waterproofing in Sammamish: what to know

Ground on a sloped lot can carry water sideways toward a foundation, especially where a hill rises uphill of the house. We look at gutter discharge, the grade on each side, and any seep line in the yard, then test the soil at the footing. A repair that ignores the route the water takes will not hold.

The outlet is the second question. A footing drain that empties toward a ravine, a neighboring lot, or the road only moves the problem. We aim for an outlet inside the parcel, and any connection to the public system is cleared with city staff first, so the repair does not add flow to a public line without approval. Cuts on a slope fall under the clearing and grading rules.

Permits and rules in Sammamish

Excavating along the foundation may need a permit, and a discharge into the public system needs approval. We ask city staff both questions before the trench is laid, and any cut into a slope is reviewed under the clearing and grading process. We check each answer for your address before we quote, so the trenching plan matches the approvals in hand.

Sammamish’s clearing and grading page says a Clearing and Grading Permit or Site Development Permit is required before site work unless SMC 16.15.050 exempts the work. It caps cut and fill slopes at 2 horizontal to 1 vertical unless the Director approves, and it says work within critical areas or their buffers cannot be exempted, except on publicly owned land. Rules change, so we confirm the current requirements with the city before we start.

How we approach it

Map gutter discharge, surface runoff, and seepage before digging
Test the soil at the footing and trace the water’s route
Correct the discharge path before changing the footing drain
Clear any public connection with city staff before it is made

For the full process, see our Basement Waterproofing page.

Our basement waterproofing work, serving Sammamish

Examples of our work. We build basement waterproofing in Sammamish and the cities around it. See all of our work

Questions from Sammamish homeowners

Why does my Sammamish basement hold water after heavy rain?

Heavy rain often pushes water toward the foundation along the surface or through a hillside. We check the gutters, grade, and footing drain before looking at deeper sources.

What must a Sammamish footing drain outlet satisfy before it is tied in?

It needs a discharge route the lot can take, and any connection to the public system needs city approval. We map the route and test whether an on-site outlet can carry the water before a connection is considered.

Does a Sammamish trench beside a foundation on a slope need a grading review?

It can. A cut into a slope falls under the clearing and grading rules, and a trench that runs beside a foundation on a slope is checked with city staff before the ground opens.