Washington County, Idaho Building Permit Guide

Washington County Planning & Zoning, 256 E Court Street in Weiser, takes building permit applications for the unincorporated county and for the Weiser area of city impact, where the County Code puts building permits under the County building inspector. Before a permit is issued the office must have your Southwest District Health septic permit, a rural fire department permit and the road approach approval, and it wants the plans 5 days ahead for plan review. Weiser and Cambridge issue their own permits inside city limits.

When does Washington County require a permit?

County Code 3-1-3 requires a permit before anyone constructs, enlarges, alters, repairs, moves, demolishes or changes the occupancy of a building or structure in unincorporated Washington County. The County’s application lists the uses it expects: new single-family residence, addition, alteration, garage, commercial, storage building, deck, cell tower, move and demolition.

Agricultural buildings are exempt from the building code under County Code 3-1-4, with conditions:

• The building sits on agriculturally zoned land that the Assessor treats as actively devoted to agriculture.
• It is designed to house farm implements, hay, grain, poultry, livestock or other horticultural products. A farm shop with a sink, toilet, shower or bathtub still counts.
• Nobody lives in it, no farm products are processed or packaged there by employees, and the public does not use it.
• The owner files an Agricultural Building Declaration Form with a site plan showing setbacks, the structure plans and proof of ownership. Engineered plans are not required, and the County does no inspections on a declared building.

If the use ever changes, a building permit is required and the building has to meet the code for its new use.

Who issues Washington County building permits?

Under County Code 3-1-3, applications go to the Planning and Zoning Administrator or the Building Official. In practice both are reached through the Planning & Zoning office, which holds the forms and reviews the plans.

Weiser area of city impact: County Code 4-1-5 makes it unlawful to start construction or occupy a building there until a building permit has been obtained from the Washington County building inspector. In that area the County also requires curb, gutter and sidewalk as a condition of the permit for new construction and for remodels covering 60% of the floor area or assessed value. The impact area boundary was redrawn by County Ordinance 100 on December 15, 2025 and land was taken out of it, so ask Planning & Zoning whether a parcel near Weiser is still inside.

For zoning, subdivision and variance requests in that area, County Code 4-1-6 (written in 2003) still names the City of Weiser as the first stop. The Planning & Zoning Administrator told the commissioners in April and June 2026 that state law now makes those hearings the County’s alone, with the City limited to a recommendation, and that the section is to be rewritten.

The 3 cities:

• Weiser: inside city limits, the City of Weiser Building Department. The City asks anyone planning to build to talk to its building inspector before starting: 208-414-1965, building@cityofweiser.com, City Hall at 55 West Idaho Street.
• Cambridge: the City of Cambridge takes its own Building Permit application at City Hall, 80 S Superior Street, 208-257-3318, with fees from its 2026 fee resolution (effective February 9, 2026) and online payment. Cambridge asks for proof that an 84 psf snow load has been met. In Cambridge’s area of city impact the building permit comes from the County (County Code 4-3-5).
• Midvale: the City publishes nothing about building permits, and the County Code sections that once covered jurisdiction and permits in the Midvale impact area were repealed in 2005, which leaves that unincorporated land under the County’s general permit rule. For a lot inside the city, ask Midvale City Hall on 208-355-2221.

Washington County application and forms

The County uses one paper Building Permit Application for every project, published in its New Building Permit Package. It has 13 numbered items:

• Items 1 to 4: owner, contractor with state registration number, architect and engineer.
• Items 5 to 7: parcel number, job site contact and address, subdivision, lot and block.
• Item 8: whether the site is in a flood plain.
• Item 9: proposed setbacks from each property line and the building height.
• Items 10 and 11: building use, and square footage of new or altered living area, garage, basement, porch, deck and shop.
• Item 12: value of improvements, which the Building Official can adjust.
• Item 13: the permit numbers from Southwest District Health, the rural fire district and the road department or highway district.

The package also carries the Weiser Valley Highway District’s right-of-way encroachment and approaches application and, for permits in the A1 zone, the nuisance waiver that County ordinance 5-4-1E requires, acknowledging that farm operations nearby have priority. Planning & Zoning’s Permits & Applications page adds the Agricultural Declaration Form and the lot split, rezone, right-of-way, special use permit and subdivision applications.

Washington County permit fees and valuation

The County sets the building permit fee from the value of the work, case by case. Neither the permit package nor the County Code prints a building permit fee table (the Code’s fee title covers only solid waste), so these are the cost facts the County does publish:

• The basis is the value of improvements you enter in item 12, and the Building Official may change that valuation.
• Fees are non-refundable and permits are non-transferable.
• For an approach onto a county road, Road & Bridge charges $150 for a right-of-way encroachment permit under Resolution 26-02, adopted January 12, 2026. Its approach permit expires 60 days after issue.
• The Weiser Valley Highway District approach application in the package, a form dated December 2018, shows a $150 application fee and, where the District requires one, a $200 impact fee. That permit is void unless the approach work is finished within 60 days of issue; the District (208-549-1761) has the current amounts.

Septic, fire department and state trade permits are charged separately by the agencies that issue them. For a firm figure on the building permit itself, phone Planning & Zoning on 208-414-3631 with the square footage and value of the project.

Electrical, plumbing, mechanical, septic and fire permits

The County’s application states that plumbing, mechanical and electrical permits and inspections are the applicant’s responsibility, and the County publishes no trade permit forms of its own. Those permits come from the State of Idaho through the Division of Occupational and Professional Licenses.

Septic: Southwest District Health, the public health district for Washington County (208-455-5400). A copy of the septic permit has to be in the Planning & Zoning office with the building plans, and County Code 3-1-3 makes the sewage permit a condition of the building permit.

Fire: a permit from the rural fire department for the site is required before the building permit: Weiser 208-414-2379, Midvale 208-355-2375 or Cambridge 208-257-3837.

Application documents, plans and site approvals

Planning & Zoning will not issue a permit until it has the septic permit, the fire department permit and plans that meet its setbacks: 15 ft from the property line, 50 ft from the center of a county road and 100 ft from a state highway. The driveway approach has to be designed and built so it does not drain onto the county road or highway.

Design criteria in County Code 3-1-2: ground snow load from 30 to 140 lb per sq ft depending on location, 90 mph wind speed, Seismic Design Category C, a frost line of 24 to 30 inches, and flood hazard areas from the June 16, 2009 flood insurance rate maps. The County adopts whatever editions of the building, residential, energy, mechanical and fuel gas codes the State has currently adopted.

Road approach: the County road supervisor must approve the culvert and the driveway approach onto a county road before a residential building permit is issued. County roads are handled by Road & Bridge at 1102 E Court Street (208-414-0950); roads in the Weiser Valley Highway District by the District (208-549-1761).

How to apply for a Washington County permit: 6 steps

Inspections and permit completion in Washington County

By signing the application you authorize the Planning & Zoning and building departments to enter the property for inspections. Final inspections are required, and so is a Certificate of Occupancy. The published contact for inspections is the Planning & Zoning office, 208-414-3631.

The Building Official can ask the applicant to back up the mechanical, structural or civil engineering of a project, at the applicant’s cost.

A permit becomes null and void if construction has not started within 6 months. Extensions follow the building code, except that a permit in the A1 zone gets only one extension.

Local Washington County filing considerations

A1 zone: every building permit issued in the A1 agricultural zone comes with a signed nuisance waiver, and only one extension is allowed.

Setbacks in the zoning code: in the A1 and A2 zones, County Code 5-3-4 keeps dwellings and other structures 15 ft from property lines and street rights-of-way and 100 ft from any state or federal highway. The owner is responsible for finding out the right-of-way width of the adjoining road.

Flood plain: the application asks whether the site is in a flood plain, and agricultural declarations are checked against the County’s flood control title as well as zoning.

Weiser impact area frontage: budget for curb, gutter and sidewalk built to the Weiser Valley Highway District and Washington County highway standards, unless irrigation district rules or easements prohibit them.

Idaho building code

Idaho’s building codes are set statewide and enforced by the cities and counties that run a building program: the 2018 International Building Code and the Idaho Residential Code (based on the 2018 IRC), the 2018 Idaho Energy Conservation Code, the 2023 National Electrical Code, and a state plumbing code based on the 2015 Uniform Plumbing Code rather than the International Plumbing Code. Idaho’s adopted codes

Official Washington County permitting resources

• Washington County Planning & Zoning
• Washington County New Building Permit Package
• Washington County permits and applications (Agricultural Declaration Form, lot split, rezone and special use)
• Washington County Code Title 3, Building Regulations
• Washington County Code 4-1-5, building permits in the Weiser area of city impact
• Washington County Road & Bridge: approach access permit
• Washington County Road and Bridge fee notice (Resolution 26-02, January 2026)
• Washington County Commissioners agendas and minutes
• Southwest District Health
• City of Weiser Building Department
• City of Cambridge forms and permits
• Idaho DOPL building program
• Idaho DOPL HVAC permit questions
• Idaho DOPL building questions

Washington County building permit FAQs

Who issues building permits in Washington County, Idaho?

Washington County Planning & Zoning at 256 E Court Street, Weiser (208-414-3631), for unincorporated land and the Weiser area of city impact. The City of Weiser and the City of Cambridge issue permits inside their limits.

How much is a building permit in Washington County?

The County prints no building permit fee table. The fee is based on the value of improvements on the application, which the Building Official can adjust, and it is non-refundable; Planning & Zoning (208-414-3631) gives the figure for a specific project.

Do I need a permit for a barn or farm shop?

Not a building permit, if it is on agriculturally zoned, actively farmed land and used only for farm purposes. You file an Agricultural Building Declaration Form with a site plan, and the building must still meet zoning setbacks and flood rules.

What do I need before I apply?

A Southwest District Health septic permit, a rural fire department permit, the road approach approval, and 2 sets of plans drawn by a registered design professional.

How far ahead should I submit plans?

At least 5 days before the date you want the permit issued, so the office can review them.

Who issues electrical and plumbing permits?

The State of Idaho. The County’s application makes plumbing, mechanical and electrical permits and inspections the applicant’s responsibility.

When does the permit expire?

It is void if work has not started within 6 months. In the A1 zone only one extension is granted.

Simplify Washington County permitting with Alliance Permitting

Alliance Permitting is a permit documentation and submission company in Idaho. We prepare your paperwork, file it correctly and coordinate with the permitting authority through issuance. We are not a contractor and we do not perform licensed plan review or inspections; that work stays with your licensed team and the jurisdiction.

This guide is provided by Alliance Permitting for general information about Washington County permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.