Basement Waterproofing in Tacoma, WA

Basement waterproofing in Tacoma: what to know

On a sloped Tacoma lot, water usually reaches the foundation from uphill. Rain that soaks in above the house travels down through the soil and loads the wall on the high side, where a daylight basement is cut into the ground. Houses on flatter ground more often have crawlspaces, and there the cause is usually grading, gutters, or a failed footing drain.

Tacoma had disconnected its storm drains from the sewer system by 1993, yet the city says it still finds private roof drains tied into the sewer by smoke testing. Digging along a wall also moves a lot of soil, which matters in North and West Tacoma, where smelter fallout left arsenic and lead in the topsoil.

Permits and rules in Tacoma

Sealing and regrading are generally not permit items, but side sewer repair or replacement takes a permit from Planning and Development Services, and connections to the storm or sanitary system can need one too. Roof drains and foundation drains can’t go to the sanitary sewer. Digging near a mapped steep slope falls under the critical areas chapter, where the usual grading exemption does not apply. Before we quote, we check what the excavation and the outlet involve.

Rules change and vary by parcel, so we confirm the current requirements with the city before we start.

How we approach it

Trace water from the uphill side, gutters, and downspouts before opening ground
Find out where the downspouts and footing drain actually discharge
Locate the side sewer and utilities before any trench along the wall
Choose exterior membrane or interior drainage based on access to the wall

For the full process, see our Basement Waterproofing page.

Our basement waterproofing work, serving Tacoma

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

Questions from Tacoma homeowners

Could my old Tacoma house have a downspout tied into the sewer?

It is possible. The city’s program to find private roof drains connected to the sewer began in 1995 and continues. We trace each downspout to its outlet during the inspection, and a connection that shouldn’t be there gets rerouted to a legal outlet.

My Tacoma basement is dry in summer and wet in January. Why?

Winter is when soil around the wall holds water. November and January average more than six inches of rain each, so a cracked wall or weak footing drain shows itself then. A seasonal pattern points to groundwater, not a plumbing leak.

Does the Tacoma smelter plume matter if I dig around my foundation?

It can in North and West Tacoma, where any property in the plume may have higher-than-normal arsenic and lead in the soil. Qualifying addresses can get sampling through the health department. Tell us if you are in the plume so the dig can be planned around it.