Short answer: it depends on your city or county. Washington’s state codes set what a replacement window has to meet. Your local building department decides whether you need a permit to put one in. Where they say no permit is needed, the window still has to meet the same code.
In every building department below, making an opening bigger, smaller, or new needs a permit.
What the building departments say
We checked each of these building departments’ published pages in October 2026. Rules and wording change, so treat this as a starting point and confirm with the building department for your address.
- Unincorporated Clark County (homes outside a city, such as Brush Prairie). A permit is required to replace windows, even the same size in the same place. The county issues a roofing, siding and windows permit for it.
- Camas. The city’s permit list shows doors and windows as needing a permit. For a like-for-like replacement, no plans are required and the permit is generally issued the day you apply. A new opening or a change in size needs plans.
- Battle Ground. The city lists window replacement of the same size as work that does not need a permit.
- Ridgefield. The city lists window and door replacement of the same size as work that does not need a permit. A different size does.
- La Center. The city lists window replacement among the projects that need a building permit.
The cities’ own wording on this is brief, and exceptions can apply, so confirm for your address. Other cities have their own rules, including Vancouver, Washougal and Woodland. They are not listed here. Ask the building department for your address.
What a replacement window has to meet, permit or not
A permit is only one part of this. These rules apply to the window itself.
- Energy. The Washington State Energy Code (2021 edition, in effect statewide since March 15, 2024) says that when some or all of an existing window is replaced, including the sash and glass, the new unit has to meet the code’s U-factor limit. The usual limit is a U-factor of 0.30 or lower. If you are replacing several windows, the code lets you average them by area. A few special cases (homes above 4,000 feet in elevation, or in windborne-debris regions) have a limit of 0.32 instead. Storm windows added over an existing window and window film put on existing single-pane glass are exceptions. Ask any installer for the U-factor of the window they are quoting.
- Escape (egress) windows. Clark County’s permit handout says egress windows still have to meet the building code’s egress rules when they are replaced. It says the sill-height rule does not apply when you replace a window in the same opening.
- Safety glass. The same handout notes that some windows may need safety glazing, depending on where they sit in the house.
When the opening changes
A larger opening, a smaller one, or a window where there was none moves framing. That is structural work, and it is the case every building department above asks for a permit for. Our guide on what each opening needs covers what we look at when we measure.
Questions worth asking your building department
- Do I need a permit to replace windows in the same size openings at my address?
- If I do, are plans required, or is there a shorter process for like-for-like windows?
- Will an inspection be needed, and who schedules it?
- If any opening gets bigger or smaller, what do you need to see?
If you live in a neighborhood with a homeowners association, it can have its own approval step that is separate from the city’s.
Where we fit
Permits depend on the city and whether the opening changes. We talk through permits with you before work starts. Our cost guide covers how permits fit into a price.
Sources
- Clark County: Residential permits and the county’s roofing, siding and windows permit handout
- City of Camas: Building FAQs and resources
- City of Battle Ground: When is a permit required?
- City of Ridgefield: Home improvement
- City of La Center: Building
- Washington State Energy Code, residential (chapter 51-11R WAC): section R503.1.1.1 and Table R402.1.3
This guide is general information, not legal advice. Your building department has the final say for your address.
Common questions
Do you need a permit to replace windows in Washington state?
Not as one statewide rule. Washington's state codes set what a replacement window must meet, but each city and county decides whether the job needs a permit. In the five building departments we checked, replacing a window with one the same size needs a permit in Clark County and Camas, and does not in Battle Ground or Ridgefield. La Center lists window replacement among the projects that need one. A new or different-size opening needs a permit in all five.
Do I need a permit if the new windows are the same size as the old ones?
It depends on where you live. Clark County (outside the cities) requires a roofing, siding and windows permit even for same-size windows. Camas treats it as a quick permit with no plans. Battle Ground and Ridgefield list same-size replacement as work that does not need one. Call the building department for your address before you start.
Does changing the size of a window need a permit?
Yes, in every building department we checked. A bigger, smaller or new opening changes the framing around it, which is structural work, so the city or county reviews it. Camas asks for plans in that case.
Do replacement windows have to meet an energy rating in Washington?
Yes. The Washington State Energy Code, residential edition, sets a maximum U-factor of 0.30 for replacement windows. If you replace several windows, the code lets you use the area-weighted average of all of them. It applies whether you replace a whole window or just the sash and glass, and the code applies statewide. A few special cases, such as homes above 4,000 feet, have a 0.32 limit instead.
How do I find out the rule for my address?
Call or visit the building department for the city your home is in, or Clark County if your home is outside a city. Give them your address and say you are replacing windows in the same size openings, or changing the size, whichever applies. Ask whether a permit is needed and whether plans are required.