ADU Construction in Whatcom County, WA

A newly constructed detached ADU with wood siding and a covered entry, situated in a residential backyard in Whatcom County, Washington. The structure sits on a landscaped lot with mature evergreen trees visible in the background.

Expert ADU Construction in Whatcom County, WA

ADU construction in Whatcom County gives homeowners a practical way to add living space without leaving their property. Sherman General Contracting handles the full build process, from site evaluation through finished construction, for attached, detached, and garage-conversion ADUs. Whatcom County zoning rules vary by district, and properties inside Urban Growth Areas now allow up to two ADUs per lot under the 2025 Comprehensive Plan update. Rural and watershed-overlay parcels carry different requirements, so getting the site details right from the start matters. Our work is grounded in the belief that quality craftsmanship and honest relationships produce better outcomes for homeowners and the broader community. Whether you want a private space for family members, a rental unit, or a flexible guest suite, we build ADUs that fit your property and hold up to the Pacific Northwest climate. Call us to talk through what your Whatcom County lot can support.

What's included

Adds a fully independent living unit to your existing property without purchasing new land
Supports multigenerational living by giving family members a private, self-contained space
Creates potential rental income from a structure built to residential construction standards
Increases long-term property value with a permanent, permitted addition to your lot
Built to withstand Whatcom County's wet winters with proper weatherproofing and drainage planning
Guided by a team committed to integrity and clear communication from first conversation to final walkthrough

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FAQ

ADU Construction FAQ

Common questions about adu construction in Whatcom County, WA.

Can I build a detached ADU on my Whatcom County property?

Many Whatcom County properties can support a detached ADU, but eligibility depends on your zoning district, lot size, and whether critical areas like wetlands are present. Sherman General Contracting can help you work through what your specific parcel allows.

What types of ADUs does Sherman General Contracting build in Whatcom County?

We build attached ADUs, detached backyard cottages, and conversions of existing structures like garages into livable units. Each type has different site and zoning considerations across Whatcom County.

Do I need to live on the property to build an ADU in Whatcom County?

Owner-occupancy rules in Whatcom County vary by zoning district and whether your lot is inside an Urban Growth Area. We recommend confirming your parcel's specific requirements before moving forward with a build.

Can I convert my existing garage into an ADU in Whatcom County?

Yes, Whatcom County allows conversion of existing structures, including garages, into ADUs even when the structure does not meet current setback standards. Sherman General Contracting handles these conversion builds throughout the county.

How many ADUs can I build on one lot in Whatcom County?

Lots inside Whatcom County Urban Growth Areas can now support up to two ADUs under the 2025 Comprehensive Plan update. Rural and watershed-overlay properties follow different rules depending on their zoning district.

Does Sherman General Contracting build ADUs outside of Whatcom County?

Yes, we also serve homeowners in Skagit County, Snohomish County, and San Juan County. Contact us to discuss your property's location and what ADU options apply in your area.

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Client Reviews

What Whatcom County customers say.

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We loved working with Sam and having him build this wheelchair ramp! He came in under other bids in time frame and cost. Great communicating when he would be on site and when different materials would be available. Respectful of our home and cleaned up really well at the end of the job. Sherman contracting is our new go-to for any contracting job.

Sam is an excellent and knowledgeable contractor- easy to work with and really knows his stuff!

Sam came and took a gigantic cottonwood tree down for me at my front driveway. His services were prompt, quality, and affordable. Would recommend to 10/10. Thanks again Sherman General Contracting 🍻

Sherman General Contraction did some significant work on our home. They did a fantastic job and I would highly recommend them. Their lead carpenter was a very skilled craftsman at the highest level.

Look no further. Sam is your guy! We just had a full bathroom remodel done and have nothing but great things to say about Sam and his crew. My husband and I have had one bad contractor experience after another for the last 4 years and Sam restored our faith in the industry. All of them are kind, respectful and skilled at what they do. They did absolutely beautiful work; they paid attention to all of the small details and noticed everything before we did so we didn’t have to point out any touch ups. We had a large amount of tile work and it was executed flawlessly. They finished on time and slightly below the estimate. We couldn’t be happier.

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Proudly Based in Whatcom County, WA

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Phone

(360) 821-4481

Hours

Monday 8:00 AM - 5:00 PM
Tuesday 8:00 AM - 5:00 PM
Wednesday 8:00 AM - 5:00 PM
Thursday 8:00 AM - 5:00 PM
Friday 8:00 AM - 5:00 PM
Saturday Closed
Sunday Closed