Basements · Second Baths · ADUs · Commercial · Rentals
Bathroom Additions Longview WA — Putting a Bathroom Where There Wasn’t One
Every other job we do starts with a bathroom that already exists. This one starts with a question: can a bathroom legally and physically go there at all?
That makes a bathroom addition Longview WA homeowners are considering the only project of ours that needs permission before it needs a permit. Five things decide it — headroom, gravity, the drain run, utility capacity and zoning — and four of the five can be checked before anybody draws anything. A good bathroom addition contractor Longview WA property owners hire should be able to tell you on the first visit which of the five is going to be the problem.
- Feasibility First
- Before any drawings
- Homes & Businesses
- Two different codes
- Permits Filed
- City or county
- Licensed & Insured
- Washington registered
An Addition Is a Different Animal From a Remodel
A remodel replaces things in a room that is already a bathroom. The drain is where it has always been, the vent already goes through the roof, the floor already carries a bath, and nobody has to ask whether the room is allowed to be there. None of that is true when you add a bathroom Longview WA houses were never designed to have. You are creating drainage, ventilation and floor area, and each one is somebody’s department — which is why a bathroom addition Longview WA owners are weighing up is quoted differently from everything else we do.
Most enquiries come from the same place: one bathroom and too many people. Longview’s older core, with its 1923 to 1934 housing, is full of three-bedroom houses with a single bathroom; the hill above it is full of 1970s and 1980s homes with an unfinished basement nobody uses. The first group usually wants a second bathroom addition Longview WA buyers now simply expect. The second is asking about a basement bathroom Longview WA houses of that era often suit well. Which is right depends far more on where the soil pipe runs than on which room you had in mind.
One honest piece of advice before you read on: if the real problem is a queue at half past seven in the morning, a half bath addition Longview WA families can fit into existing floor area solves it for a fraction of the cost of a full one. No bath, no shower, far less drainage, often no new ventilation run. Ask about that first. It is frequently the right answer and always the cheaper one.
The second thing worth saying early is that two of the jobs on this page are not family homes at all. A commercial bathroom remodel Longview WA business owners need is governed by a different code book with occupancy-based fixture counts, and it can pull in federal accessibility law that never touches a private house. A rental property bathroom remodel Longview WA landlords commission is a residential job, but it arrives with a tenant, a notice period and a different argument about what to specify. Both get their own section below rather than a paragraph. A third case sits between them: a garage conversion bathroom Longview WA owners are adding to create an ADU is domestic work that nonetheless creates a second household, with all the utility questions that follow.
Where this work overlaps our other pages we have linked rather than repeated. New pipework itself is a bathroom plumbing rough-in Longview WA job and lives on Bathroom Repair; what goes in the new room is Shower & Tub and Vanities & Fixtures; the floor it stands on and the surfaces around it are Tile & Flooring; and if the new bathroom is being added so that somebody can stay in the house, read Accessible Bathrooms alongside this one.
Five Things That Decide Whether a Bathroom Can Go Where You Want It
In rough order of how often they stop a job. The first two are measurable in an afternoon with a tape and a torch, which is why we settle them before anything else. Any bathroom addition contractor Longview WA residents interview should walk the drain route before talking about finishes.
1. Headroom — and the number is lower than you think
The 2021 Washington State Residential Code, in force since 15 March 2024, sets it out at R305.1: habitable rooms need seven feet, but “bathrooms, toilet rooms and laundry rooms shall have a ceiling height of not less than 6 feet 8 inches”. Over a showerhead you need that same 6 feet 8 inches across an area of at least 30 inches by 30 inches. Beams, girders and ducts in a basement may come down to 6 feet 4 inches. So a basement that fails as a family room can still pass as a bathroom — which is why a basement bathroom addition Longview WA homeowners had written off is worth measuring again.
2. Gravity — which way does the water go?
Everything above the sewer drains itself. Everything below it does not. Section 710 of the plumbing code — which Washington adopts without amendment — requires a backwater valve where a fixture sits lower than the next manhole cover upstream, and requires fixtures below the crown of the main sewer to drain into a sealed sump and be lifted out by an approved ejector or pump. That is why a basement bathroom addition Longview WA homes can accommodate has a moving part, and a power supply, that no upstairs bathroom needs.
3. The drain run — distance, fall and corners
A bathroom two rooms from the existing stack is not simply more pipe. Washington’s amended 707.4 requires a cleanout at the upper terminal of each horizontal drain, one per hundred feet of developed length, and “an additional cleanout… for each aggregate horizontal change of direction exceeding 135 degrees”. Under a floor, 707.9 says no cleanout may sit more than twenty feet from an access door or trap door. Every corner the new branch turns must be paid for and reachable later.
4. Capacity — and a City sequencing rule
New fixtures add demand on the water service and the sewer, and somebody has to agree the connection can take it. The City of Longview makes the sequence explicit: on new construction “no permits can be issued until the utility permit has been paid in full with receipt submitted as proof of payment”. Kelso reaches the same place differently — separate permits are required for connections to utilities. Either way the utility question comes before the building permit, not after. Expect it to be asked hardest of an ADU bathroom Longview WA properties are gaining or a garage conversion bathroom Longview WA zoning treats as a new dwelling, because those add a household rather than a fixture.
5. Permission — zoning before building code
If the work grows the building’s footprint, the building code is the second hurdle and zoning is the first: setbacks from your boundaries, how much of the lot may be covered, and whether the use is allowed at all. In a mapped flood hazard area there is a further layer, set out on West Side Highway and West Longview rather than repeated here. Staying inside the existing walls skips this gate entirely, which is why a half bath addition Longview WA houses can absorb internally is so often the quickest route to another bathroom.
Six Ways to Get Another Bathroom Into a House
Listed cheapest first, which is roughly the reverse of how people usually ask. Most of the value on a bathroom addition Longview WA property owners are planning is created in this conversation, before a wall is opened: the option somebody arrives asking for is often the fourth-best available to them. Whichever route you take, a bathroom addition contractor Longview WA residents can rely on should show you all six and say which the building prefers.
A half bath in found space
Under the stairs, the end of a hallway, a corner of an oversized laundry. A toilet and a basin need far less drainage than a shower and no new floor area at all. A half bath addition Longview WA homeowners carve out of existing space is the fastest return on this page.
A second bathroom off an existing one
Splitting an oversized bathroom, or borrowing from the bedroom next door, puts the new fixtures within feet of pipework already there. A second bathroom addition Longview WA houses can take this way is the least disruptive option, because the drain, the vent and the hot water all arrive at that wall already.
A basement bathroom
The most common request on the hill and in Kelso’s daylight basements. A basement bathroom addition Longview WA homes can support hinges on the two gates above — headroom and gravity — plus whether there is somewhere sensible to put a sump. A daylight basement that walks out at the back is a far easier proposition than one buried on all four sides, and it is the one case where a basement bathroom Longview WA properties gain may need no pump at all.
An upstairs bathroom
Easy for drainage, harder for everything else. Water runs downhill, so the fall looks after itself; the questions are what the new floor stands on and where the vent and the branch can drop without landing in the middle of the kitchen ceiling. We work that route out on the first visit, because it decides where the room can be.
A garage conversion or an ADU
An attached garage already has walls, a roof and a slab, which makes a garage conversion bathroom Longview WA houses can gain the cheapest square footage on most properties. If it is becoming a separate living space the code is blunt: R306.1 says every dwelling unit shall have a water closet, a lavatory, and a bathtub or shower. So an ADU bathroom Longview WA owners are planning is not optional — it is what makes the unit a unit, and an ADU bathroom Longview WA zoning will accept comes with a water and sewer capacity question attached.
A built addition
New floor area, on new footings, under new roof. The only option that answers to zoning as well as the building code, and the only one where the fifth gate applies in full. It is also the one that gives you the bathroom you wanted rather than the bathroom the house allowed, which for some clients is the entire point.
In a Business, the Building Tells You How Many Bathrooms You Need
A commercial bathroom remodel Longview WA business owners commission is not a bigger version of a domestic one. It is a different code book, a different arithmetic, and one federal obligation that never reaches a private house.
The fixture count follows the use, not the staff list
Washington does something here that catches people out. It adopts the Uniform Plumbing Code but removes that code’s own fixture tables: amended section 422.0 says that for the minimum number of fixtures you must see “Building Code Chapter 29 and Table 2902.1”, and that “Sections 422.1 through 422.5 and Table 422.1 are not adopted”. A count worked out from the plumbing code’s own table is worked out from a table this state never adopted.
The table that does govern produces a result owners find hard to believe. Under Table 2902.1 an office or bank — occupancy B — needs one water closet per 25 occupants for the first fifty, then one per fifty. The identical building used as a shop — occupancy M — needs one per 500. A restaurant sits at one per 75. Change what a downtown storefront is used for and the requirement can move twentyfold, which in a small city is an ordinary event rather than an edge case. Section 2902.1 adds that occupant numbers “shall be determined by this code”, so the count follows a calculated occupant load, not your payroll.
You may need fewer rooms than you fear
The most expensive assumption in small-business work is that two rooms are always required. Section 2902.2 does require separate facilities for each sex where fixtures are required — then lists exceptions. They are not required in a tenant space whose total occupant load, staff and customers together, is 15 or fewer; nor in a mercantile occupancy of 100 or fewer; nor in a business occupancy of 25 or fewer; nor in a space used mainly for eating or drinking with 30 or fewer. Many premises here sit inside one of those numbers, and a commercial bathroom remodel Longview WA owners budget on that basis costs a great deal less than one budgeted on the assumption.
Two layout rules that catch small premises
Section 2902.3.1 says the route to a required public toilet “shall not pass through kitchens, storage rooms or closets” — which rules out the arrangement half the older storefronts in this county actually have. And 2902.3.2 says a toilet room “shall not open directly into a room used for the preparation of food” for the public. Both tend to be discovered at plan review rather than before it.
And here the ADA genuinely does apply
Our Accessible Bathrooms page explains that the Americans with Disabilities Act does not reach a private home. A business is the opposite case, and the trigger is wider than owners expect. The ADA National Network states that alterations which could affect usability must be made accessible “to the maximum extent feasible”, and that where you alter a primary function area — the dining area of a cafeteria is their own example — an accessible route to it must be provided and the bathrooms serving that area must also be made accessible, with that extra work required only up to “20% of the cost of the original alteration”.
Read that twice if you own premises here: redecorating your dining room can oblige you to spend up to a fifth of that budget again on the restroom. It is also why so much commercial work reaches us attached to a project that was about something else. Compliance is measured against the 2010 ADA Standards, whose figures are on our accessibility page rather than duplicated here.
With a Tenant in the Building, the Calendar Is Not Yours
A rental property bathroom remodel Longview WA landlords are planning runs under the same code as any other house, so nothing in the first half of this page changes. What changes is that somebody lives there, and that governs the programme rather than the specification.
Washington’s Residential Landlord-Tenant Act requires an owner to give a tenant at least two days’ notice before entering to carry out repairs, and to enter at reasonable times. An owner cannot authorise a start tomorrow, and a crew arriving before notice has been served puts the owner in the wrong rather than the contractor. We ask for the notice date before booking anything. Check the current notice period for your own circumstances, because the Act sets out particular cases.
The specification argument differs too. Owner-occupiers choose for taste; whoever commissions a rental property bathroom remodel Longview WA tenants will live in should be choosing for the next fifteen years of turnovers. That means fewer grout joints rather than more, a one-piece surround over a tiled one where the budget is tight, surface-mounted fittings a plumber can change without opening a wall, and ventilation sized properly, because nobody ever reports a fan that is merely weak.
Two notes for owners. In a duplex, the most reliable way we see of moving a unit up a rent bracket is to add a bathroom Longview WA renters will use daily rather than refit the one already there, and a second bathroom addition Longview WA investors are costing often shares a wall with the existing stack. And where a rental is a manufactured home the permit question moves to a state agency: a mobile home bathroom remodel Longview WA owners are planning is set out on Accessible Bathrooms, which carries the Labor & Industries alteration-permit path in full.
Before you commit to a date
Serve the notice, then book the trades — not the other way round. On a rental property bathroom remodel Longview WA owners want finished quickly, that order is the whole difference between a smooth job and an angry one.
The One Bathroom Job That Cannot Use the Fast Lane
Our Shower & Tub page records something cheerful: a Longview plumbing permit is a “One Stop” type you can be issued online, which is the quickest paperwork in the county. This page records the opposite. A bathroom addition Longview WA departments review needs drawings, and the City is explicit that if your submittal includes plans you must “make arrangements to submit your application package by other means”. Plan on weeks, not minutes, and build that into your timetable before you give anybody a date.
City of Longview
The permit trigger names this work directly: a building permit is required for all new construction and all “alterations, additions, improvements, and repairs of existing buildings”, with separate plumbing and mechanical permits alongside. The counter runs Monday to Thursday, shut on Fridays. Note that the City publishes two different residential review times on the same page — two to four weeks in one place, five to ten business days in another. We plan on the longer.
City of Kelso
Kelso publishes its own figure plainly: permit approval “usually takes about 3 to 5 weeks”, varying with complexity and time of year. Utility connections and any work in the public right-of-way need separate permits, and electrical goes to the state rather than the City, as our Kelso page sets out. The finish-work exemption that helps a tile job does not help an addition.
Unincorporated Cowlitz County
On the hill or along the river rather than inside a city, your counter is the County’s in Kelso, and there is an extra gate in front of the building permit: Environmental Health must confirm approved water and sewer first. Set out in full on Longview Heights and West Side Highway. On a well and a septic system it is the gate that decides the project.
Castle Rock and Kalama
In Castle Rock establish which side of the city limit you are on first, because most 98611 addresses are not inside it — and that decides both the department and whether the County gate above applies. Kalama is the opposite problem: not the counter but the calendar, since the City inspects on two days a week against a published list of thirteen inspections. A long job gets programmed backwards from that.
Everywhere: the 180-day clock
Both cities set the same limit, and it bites long projects rather than short ones. A Longview permit is valid for 180 days and an inspection must be performed every 180 days to keep it active. Kelso’s expires if work has not started within 180 days, or if no inspection is requested for that long, though it will consider a written request for an extension. An addition that stalls over a winter is exactly the job that meets this.
Tell Us Where You Want It and What Is Below It
The second half of that sentence decides the project. Tell us the room you have in mind, what sits underneath it, whether there is a basement, whether you are on city sewer or a septic system, and whether this is a home, a business or a let. If you want to add a bathroom Longview WA building departments will need to see drawings for, we would rather find that out on day one than on week six. We walk the drain route, measure the headroom, confirm which department issues your permit and put the feasibility in writing before anybody pays for a drawing.
Addition Questions We Are Asked Most
My basement ceiling is low. Can I still put a bathroom down there?
Quite possibly, because bathrooms get a lower limit than living space. The Washington residential code requires seven feet for habitable rooms but only 6 feet 8 inches for bathrooms and toilet rooms, with the same 6 feet 8 inches over a 30 by 30 inch area at the showerhead, and beams or ducts allowed down to 6 feet 4 inches. So a basement bathroom Longview WA homeowners were told was impossible for a family room can still work as a bathroom. Measure to the lowest projection over where the fixture will stand, and allow for the finished floor.
Why does a basement bathroom need a pump when the rest of the house does not?
Because waste only flows downhill, and in a basement there is often no downhill left. Section 710 requires fixtures below the crown of the main sewer to discharge into a sealed sump and be lifted out by an approved ejector or pump, and requires a backwater valve where a fixture sits lower than the next manhole cover upstream. That is real mechanical kit needing power and service, and the honest extra cost of a basement bathroom addition Longview WA properties mostly cannot avoid. A daylight basement walking out at grade is the exception, and the one basement bathroom Longview WA homes can sometimes build on gravity alone.
How long does the permit take for an addition?
Weeks, and you should plan on that. Because an addition needs drawings it cannot use Longview’s online “One Stop” route; the City asks that submittals including plans come in by other means. Longview publishes two residential review figures on the same page, two to four weeks and five to ten business days, so we work to the longer. Kelso publishes about three to five weeks. In unincorporated county, Environmental Health approval for water and sewer must come before the building permit. Any bathroom addition contractor Longview WA owners hire should give you these dates in writing.
How many bathrooms does my business actually have to have?
It depends on your occupancy classification and calculated occupant load, not your headcount. Table 2902.1 of the Washington State Building Code puts an office at one water closet per 25 occupants for the first fifty and a retail shop at one per 500 — the same building, a different use, twenty times the requirement. Two separate rooms are often not required at all: the code waives that for a business occupancy of 25 or fewer, a shop of 100 or fewer, and an eating or drinking space of 30 or fewer. A commercial bathroom remodel Longview WA owners are quoting should start there, because that number sets the budget.
Does adding a bathroom pay for itself?
We will not put a percentage on it, because we would be making it up and it varies by street and by year. What we will say is which version has the best chance. Going from one bathroom to two in a three-bedroom house is the change most likely to widen the pool of buyers who will consider the property; two to three is far more about how you live in it. For an investor, a second bathroom addition Longview WA renters use daily is a different calculation again, and the one case where we would say ask a local agent before you ask a builder.
Can you work in my rental while the tenant is living there?
Yes, with notice and a realistic plan for the days the bathroom is out of use. Washington’s Residential Landlord-Tenant Act requires an owner to give the tenant at least two days’ notice before entering for repairs and to enter at reasonable times, so the start date is set by that notice rather than by our diary. Where the property has only one bathroom we stage the work so it is usable overnight wherever possible, and say in advance when it will not be. Confirm the current notice requirement for your circumstances before committing to a date.
Find Out If It Can Go There Before You Pay for a Drawing
From a half bath addition Longview WA houses can absorb internally to a built extension, a basement conversion or a shopfront restroom — headroom measured, drain route walked, jurisdiction confirmed in writing before anyone pays for a drawing. If you want to add a bathroom Longview WA, Kelso or Cowlitz County property has never had, the first question is whether it is possible at all, and that is the question we answer first.