#1 ADU Contractor in Crestline
Custom Builds by Horizon Remodeling

Finding the right adu contractor in Crestline means working with someone who understands both California’s current ADU statutes and the mountain-specific requirements that apply to every project on this hill. California consolidated its ADU law into Government Code sections 66310 through 66342 in 2024, and the rules shifted again on January 1, 2026. Square footage is now calculated as interior livable space rather than overall building area. Once you submit an application, the reviewing agency has 15 business days to determine whether it is complete and 60 days to issue an approval or denial. That approval is ministerial, meaning no public hearing and no discretionary design review stands between a complete application and a decision.

Because Crestline sits in unincorporated county territory, your application goes to San Bernardino County Land Use Services, Building and Safety rather than to a city planning department. The county adopted a new ADU chapter, Development Code Chapter 84.36, at the Board of Supervisors on January 13, 2026, making it the most recently updated county ordinance in the region. Published standards allow a primary ADU ranging from 200 up to 1,200 square feet and a junior ADU up to 500 square feet. An attached ADU may reach 25 feet in height, while a detached unit is limited to 18 feet with two additional feet permitted to match an existing roof pitch. Side and rear setbacks are four feet, and detached structures require five feet of separation from other buildings. The county also allows two ADUs per lot and three units on parcels of five acres or more, which differs meaningfully from most coastal jurisdictions.

Mountain Region design rules add a layer of requirements that do not appear in lowland projects. Footings must be set to an 18-inch frost line depth. Any new or altered roof must be designed for local snow loads. Where down-slope eaves pitch steeper than 4:12, exits below those eaves require protection from sliding snow and ice. These are not optional upgrades; they are standard county conditions for any permitted structure in this elevation band, and we account for them in structural drawings before anything goes to plan check.

Sewer determines feasibility on many parcels here before anything else does. Connection to a public sewer line is required when one runs within 200 feet of the property line, and that threshold increases by 100 feet for each additional dwelling unit added to the lot. When a connection is not required, the project relies on septic or an advanced treatment system. We bring San Bernardino County Environmental Health into the conversation at the beginning of planning, not after a design is already drawn, because the answer on sewer or septic shapes the size and placement of whatever unit we build.

The land itself sets the remaining constraints. Crestline grew from a weekend cabin community beginning in the late 1930s, after the Lake Gregory dam was completed with Works Progress Administration funding, and it continued filling in through the rest of the twentieth century. Most homes are small one or two-story cabins sitting on narrow sloping lots, with kitchens compressed into a corner of the main floor and earlier additions stacked uphill or downhill rather than extended sideways. That pattern directly affects where a detached ADU can be sited and how far utilities need to run from the existing structure. We read the lot, the slope, and the utility layout together so that the plan we draw is one the county will approve and the site can actually support.