Utilities and site work
for detached units.

The part that goes in the ground.

A detached cottage needs water, sewer, and power run out to it, and it needs a foundation that works on Bellingham's wet ground. This is the site and utility work that makes a backyard unit possible. We trench and connect water and sewer, run the electrical out to the unit, upgrade the main panel when a kitchen and heat pump need more service, and pour the foundation. We also handle the grading and stormwater work so water drains away from the cottage instead of pooling under it.

On our wet ground, drainage is not an afterthought. A cottage on a poorly drained pad sits in a puddle every winter, and that is how foundations and crawlspaces go bad. We grade the site, manage the stormwater to meet the City or County rules, and set the foundation so the unit stays dry for the long haul. This work is often the difference between a detached ADU that lasts and one that fights moisture from year one.

What it actually costs.

Our four-step process.

1. Site assessment

   We locate your sewer, water, and panel, check the grade and drainage, and scope the dig.

2. Permit and plan

   We plan the utility runs and stormwater, and pull the permit with the City or County.

3. Trench and connect

   We trench and connect water and sewer, run power, upgrade the panel, and pour the foundation.

4. Grade and restore

   We grade for drainage, finish the stormwater work, and restore the yard.

Why hire a real crew for this.

• Water, sewer, and power run out to a detached unit
• Panel and service upgrades for a second kitchen and heat pump
• Foundation set for our wet ground
• Grading and stormwater to meet City or County rules
• Yard restored when the dig is done

Frequently asked questions.

How much does utility and site work cost for an ADU in Bellingham?

Utility and site work for a detached ADU in Bellingham usually runs $20,000 to $60,000. The biggest driver is how far the unit sits from your existing sewer, water, and electrical panel, because that distance sets the trenching cost. Sewer depth, whether your main panel needs an upgrade to carry a second unit, and the stormwater work your lot requires all move the number too. We scope it on site before we quote.

Do I need to run new sewer and water to a backyard ADU?

Almost always, yes, for a detached unit. A backyard cottage needs its own water and sewer connections trenched out from your existing lines, and its own power run from the panel. Sometimes the main panel needs an upgrade so it can carry the second kitchen and a heat pump. We handle the trenching, the connections, and the panel work, and we pull the permits with the City of Bellingham or Whatcom County.

Why does drainage matter so much for a Bellingham ADU?

Because our ground stays wet for much of the year. A cottage on a pad that does not drain sits in standing water every winter, and that is how foundations crack and crawlspaces grow mold. We grade the site so water moves away from the unit, build the stormwater management the City or County requires, and set the foundation to stay dry. Good site work is what makes a detached ADU last.

Related services.

ADU site and utility work across Whatcom County.

Ground conditions and utility distances change across Whatcom County. Pick your area: