Home Remodeling in
Allyn, WA
Allyn is an unincorporated urban growth area with zoning of its own. Hillside lots, hardpan soils and a shared sewer system shape an addition or ADU as much as the floor plan does.
Remodeling in Allyn
What building in Allyn actually involves
Allyn is an unincorporated community on the western shore of North Case Inlet in north Mason County, between Belfair and Shelton. It has no city government, so permits come from Mason County, but it is a designated urban growth area with its own zoning code.
The growth area covers about 1,244 acres in two parts: Lower Allyn, the original townsite along the shoreline and State Route 3, and Lakeland Village, a large planned residential community on the slopes to the west, which includes both year-round and seasonal homes.
Slopes and hardpan soils
The ground rises quickly from the water, with grades of up to 13 percent and elevations over 350 feet near Sterling Drive. Mason County's Allyn plan notes that the dominant Alderwood and Sinclair soils have a cemented hardpan layer that restricts drainage.
For an addition, a garage or a detached ADU, that means drainage and foundation design deserve attention early. Water that cannot soak in has to be directed somewhere, and on a slope that affects neighbours as well as your own footings.
Sewer, water and ADUs
Most of Allyn is served by Mason County PUD No. 1 for water and by the North Bay/Case Inlet Sewer System, which was completed in 2000. The county's 2025 plan estimates the sewer has about 25 percent spare capacity.
Allyn's zoning, Mason County Code 17.10 to 17.15, requires every ADU to be connected to public sewer and water or to approved systems. Because Allyn is an urban growth area in a fully planning county, HB 1337 has applied since 30 June 2026, requiring two ADUs per lot to be allowed and barring caps below 1,000 square feet.
Plans and permits
Mason County drafted an updated Allyn UGA Subarea Plan in October 2025, alongside its countywide comprehensive plan update, so check for newly adopted changes before designing.
Building permits come from the Mason County Permit Center, Building 8, 615 W. Alder St. in Shelton, on (360) 427-9670 ext. 352.
Local requirements on this page were last checked on 19 September 2026. Codes change, so confirm current standards with Mason County before you apply.
What We Build
Our services in Allyn
Client Reviews
What our clients say
“Chris and his crew are very friendly and professional. They did an awesome job. The house looks great. They made sure all garbage and paint was cleaned up. Very pleased with this company. Would use them again.”
Exterior painting
“I Had a small area of deck that was rotting and needed to be replaced. Thomas Hansen made all arrangements, and Irving did the labor/work. I couldn't be happier with the outcome. Thomas and Irving were both very professional, courteous, punctual, and I told them that your company is my forever GC. If there were 10 stars, I would rate them that high. So so happy with the results.”
Deck construction
Common Questions
Remodeling in Allyn, answered
Is Allyn a city?
No. Allyn is unincorporated, so Mason County issues permits, but it is an urban growth area with its own zoning code, Mason County Code 17.10 to 17.15.
Can I build an ADU in Allyn?
Yes. HB 1337 has applied in the Allyn urban growth area since 30 June 2026, and Allyn's code requires each ADU to connect to public sewer and water or approved systems.
Where do I get a building permit for Allyn?
From the Mason County Permit Center, Building 8, 615 W. Alder St., Shelton, on (360) 427-9670 ext. 352.
Do you work in Allyn?
Yes, in Lower Allyn and Lakeland Village. Call (253) 348-1847 for a free estimate.
Service Area
Where we work in Allyn
More Areas
Other areas we serve
- SheltonMason County
- LaceyThurston County
- TumwaterThurston County
- YelmThurston County
- TeninoThurston County
- TacomaPierce County
- LakewoodPierce County
- PuyallupPierce County
- Gig HarborPierce County
- SteilacoomPierce County
- DuPontPierce County
- SpanawayPierce County
- CentraliaLewis County
- ChehalisLewis County
- OlympiaThurston County
- FircrestPierce County
- University PlacePierce County
- EdgewoodPierce County
- MiltonPierce County
- Browns PointPierce County
- Lake TappsPierce County
- ElmaGrays Harbor County
- McClearyGrays Harbor County
- MontesanoGrays Harbor County
- RochesterThurston County
- Grand MoundThurston County
- RoyPierce County
- RainierThurston County
- BucodaThurston County
- WinlockLewis County
- SeattleKing County
- KentKing County
- AuburnKing County
- BremertonKitsap County
Planning a project in Allyn?
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Also serving Olympia, Tumwater and the wider South Puget Sound.