In a Kirkland condo, your association's written rules decide which floors you can install. Most of those rules come down to one number, the impact insulation class (IIC). It rates how well the floor and ceiling between two homes keep footsteps from reaching the home underneath. The underlayment and install method move it far more than the flooring you pick.
Condo in a concrete building. Most floors can pass here with the right layer under them. A bare 6-inch slab already blocks voices well, at about STC 50 to 55 in lab data compiled for the concrete industry. For footsteps it rates only IIC 26 to 30, and Washington's building code sets IIC 50 as the lab minimum between units in new buildings. A plank with a thin attached pad lands near that line on bare concrete, so check your rule's number before assuming the pad is enough.
Condo in a wood-framed building. The same number is harder to reach and harder to predict. Floors over wood joists test lower than the same floors over concrete. ASTM, which writes the sound tests, warns that underlayment makers' delta IIC figures can't be used to estimate results on plywood floors. Ask for a test on a wood-framed floor like yours, and expect carpet in bedrooms or a heavier sound system to come up.
Townhome. A sound rating usually has nothing to protect unless someone lives under your floor. Side-by-side townhomes share walls, not floors, so the real question is whether your declaration says anything about interior flooring at all. If your townhome is stacked over another home, treat it like a condo.
Carpet over a cushion passes an impact rule most easily. Every hard floor needs the right layer under it, and the flooring's maker decides which layers are allowed.
| Floor | What goes under it | Against an IIC rule | Watch for |
|---|---|---|---|
| Carpet and cushion | Cushion that meets the carpet maker's spec | Easiest to pass | Cushion thicker than 7/16 inch |
| Luxury vinyl plank (LVP) | Attached pad or a maker-approved acoustic layer | Thin pads land near 50 on bare concrete | Adding a pad the maker doesn't allow |
| Engineered hardwood | A tested sound layer, floated or glued | Can pass as a tested system | Nails through the sound layer |
| Laminate | Attached pad or an approved sound layer | Can pass as a tested system | A missing expansion gap at walls |
| Tile | Bonded sound reduction membrane | Depends on the membrane | Extra height at doorways |
The rest of this page starts with the rules and who enforces them, including a note for buyers. Then come the ratings, your building, each type of floor, underlayment, the approval request, install day, neighbor complaints and quick answers.
What Kirkland condo and townhome flooring rules usually say
Your flooring rule is in your association's governing documents, meaning the declaration (often called the CC&Rs), the bylaws and the board's rules. Condo flooring rules usually set a minimum sound rating or name an approved underlayment or sound system. They can also require written approval before work starts and limit work hours and elevator use. The National Wood Flooring Association (NWFA), whose installation guidelines installers work from, says association standards "will supersede, and are often more-stringent than, the minimum building code requirements."
Who controls the floor in a Washington condo
Under Washington law, the finished flooring in a condo belongs to your unit, but the floor underneath it doesn't. Unless your declaration says otherwise, the Washington Condominium Act and the newer Washington Uniform Common Interest Ownership Act both count "finished flooring" as part of the unit. Everything else in the floor is a common element.
The newer law also makes an owner's right to improve a unit subject to the governing documents. So the new floor is yours to choose and pay for, and the board still has a say in what goes under it.
Do you need a permit to replace flooring in Kirkland?
No, not for the flooring itself. The City of Kirkland's permit page lists "painting, papering, tiling, carpeting, cabinets, countertops and similar finish work" among projects that don't need a permit. The one condition is that existing accessibility features aren't changed. So in Kirkland, your association is the one reviewing a condo floor change, and its rule is the one to meet. If the job goes beyond the floor finish, the city advises checking with its Development Services office before you start.
How to find your building's flooring rule
Ask your property manager or board for three things in writing: the flooring or alteration rule, the request form, and any list of approved products. Then pin down what the rule leaves vague. Find out the number it requires, whether that's a lab rating or a field test, and which rooms it covers. The NWFA tells installers to get the CC&Rs before bidding a job, because the documents may already name the sound system.
Read the flooring rule before you buy a Kirkland condo
If you're buying a condo with carpet and picturing hard floors, read the flooring rule before you sign. Washington requires sellers to give buyers a resale certificate that includes the declaration, the bylaws and the association's rules. It also has to say whether the association knows of alterations to the unit that break its rules. That's where you'd see whether existing hard floors have been flagged. Under the newer common-interest law, a buyer isn't liable for an alteration violation the association should have known about but left off the certificate.
IIC and STC sound ratings, explained
The impact insulation class (IIC) rates how well a floor and the ceiling under it stop impact noise, like footsteps, dropped objects and chairs sliding across the floor. The sound transmission class (STC) rates how well they stop airborne sound, like voices, music and TV. Higher is better for both.
For floors between units in new buildings, Washington's building code requires IIC 50 and STC 50 in a lab test. In a field test in the finished building, the line is 45 for each. That's the 2021 International Building Code, which took effect statewide in March 2024.
Ten points is a big step. The ratings are built from decibel measurements, and the NIH's hearing institute notes that "an increase of 10 dB seems about twice as loud to your ears." A floor rated IIC 60 lets through much less footstep noise than one rated IIC 50.
Why condo flooring rules focus on IIC
Condo flooring rules focus on IIC because the building's structure already stops most airborne sound, and footsteps are where a new floor makes the difference. Lab data compiled by an acoustical consulting firm for the National Ready Mixed Concrete Association shows why. A bare 6-inch slab rates STC 50 to 55 but only IIC 26 to 30, so it meets the airborne line on its own and falls about 20 points short on impact. A new floor doesn't change the slab's mass, which the NWFA names as a main influence on STC.
Lab ratings and field ratings are different numbers
A lab rating and a field rating for the same floor won't match, and the field number usually comes out lower. In the lab test (ASTM E492), sound can travel only through the test floor. ASTM says lab ratings "represent an upper limit to what would be measured in a field test." A field test in a finished building also picks up every side path sound takes through walls and structure.
The building code allows 5 points for that gap, asking for 50 in the lab or 45 in the field. Ask your association which kind of number its rule means before you choose a product. A 55 in the lab and a 55 in a finished building are very different targets.
How to compare underlayments with delta IIC
Delta IIC shows what a floor covering or underlayment adds on its own. In the delta IIC test (ASTM E2179), a lab rates a bare concrete reference slab, then rates it again with the flooring and underlayment on top. The NWFA defines delta IIC as the second rating minus the first, on a nominal 6-inch slab. Because every product is tested the same way, it's the fairest way to compare underlayments for a concrete building.
Delta IIC only works on concrete. ASTM's test method warns that its results must not be used to estimate floors made of "only one or two lightweight floor layers such as oriented strand board or plywood." In a wood-framed building, ask for a full IIC test on a wood-framed floor instead.
What a sound rating can't tell you
A floor can meet its number and still bother someone, because a rating leaves out three things condo owners notice.
- The low thud of walking. ASTM says IIC "does not deal with low frequency sounds below 100 Hz," the kind people make walking on lightweight joist floors, or with the squeaks of loose framing.
- Sharp clicks from hard shoes, pet claws and dropped objects. ASTM created a separate high-frequency rating, HIIC, for these sounds, and it can't stand in for IIC.
- Your own room. IIC measures what reaches the room underneath, and no standard rating measures how the floor sounds to you as you walk on it.
Most of the letters on a spec sheet or an HOA letter are the same two measurements, impact and airborne. The difference is whether they were taken in a lab or in a finished building.
| Rating | What it measures | Where you'll see it |
|---|---|---|
| IIC | Impact noise through a floor-ceiling, in a lab | Flooring and underlayment spec sheets |
| AIIC, NISR or FIIC | Impact noise in the finished building | Field test reports, some HOA rules |
| Delta IIC | What a covering adds on bare concrete | Underlayment spec sheets |
| STC | Airborne sound through a floor or wall, in a lab | Building specs, some HOA rules |
| NNIC | Airborne sound in the finished building | Field test reports |
| HIIC | Sharp, high-pitched impacts | Newer test reports |
How your building's construction changes the answer
The same floor and underlayment can score very differently in different buildings, so find out what your floor is built from before you choose products. As ASTM's delta IIC method puts it, "The same floor covering in combination with different basic floor assemblies will not always give the same impact insulation class (IIC)" rating. Your property manager or the building's plans will tell you whether your unit sits on a concrete slab or a wood-framed floor.
Concrete condo buildings
Concrete condo buildings give a new floor the best start. The slab's mass handles airborne sound, and a tested underlayment can supply most of the impact rating a rule asks for. The NWFA's guidelines show engineered wood floated over an acoustic underlayment or glued over one bonded to the slab. Solid wood is nailed to a plywood subfloor that floats over the sound layer.
Settle two things before anything is ordered. First, find out whether the slab is post-tensioned, a question our guide to solid and engineered hardwood in Bellevue condos walks through. Second, have the slab tested for moisture, which the NWFA calls "compulsory practice" before any wood floor goes in.
Wood-framed condo buildings
Wood-framed condo buildings make the same rule harder to meet. A product manager at a flooring distributor made the point in Hardwood Floors, the NWFA's magazine. He compared the same engineered floor and underlayment in a wood-frame low-rise and a concrete high-rise. His conclusion was that "the building's construction has an outsized impact on acoustic performance."
The lab numbers agree. In the concrete industry's compiled data, wood-joist floors with a drywall ceiling and a thin gypsum-concrete topping, but no acoustic underlayment, rate IIC 29 to 35. In the carpet industry's tests, the same carpets and cushions scored 12 to 15 points lower over wood joists than over concrete. They still rated IIC 54 to 68.
So carpet in bedrooms is the surest way through a strict rule in a wood-framed building. For hard floors, ask for a lab IIC on a tested wood-framed floor as close to yours as possible, or a field test in your building. And expect some thud to remain, since IIC doesn't measure the low boom of footsteps on joist floors.
Townhomes
Townhomes rarely face a sound-rating question unless someone lives under your floor. The building code's sound rules are written for floors and walls between separate homes. In a side-by-side townhome, your neighbor is on the other side of a wall. Washington's newer common-interest law lets owners improve their own units subject to the governing documents, so read what your declaration says about interior floors. If your townhome is stacked over another home, the condo rules apply.
Noise through the shared wall is an airborne, STC question for the wall itself, and a new floor won't change it. Underlayment still earns its place in a townhome, though, for comfort underfoot and for the noise that carries between your own floors.
How each type of floor meets a condo sound rule
Each floor type gets to a sound rule its own way. Carpet brings its own cushion, while hard floors rely on an underlayment or membrane. The flooring maker's installation guide also limits what can go under each floor. Break those limits and you can void the warranty, so the guide matters as much as the rating.
Carpet and cushion
Carpet over a cushion is the easiest floor to get through an impact rule. In lab tests by the Carpet and Rug Institute, the carpet industry's trade group, a bare concrete floor-ceiling rated IIC 34. Carpets alone rated 53 to 70, and one carpet that rated 68 by itself rated 73 to 80 over different cushions. That's why some buildings ask for carpet in bedrooms.
The cushion has to suit the carpet as well as the building. The institute's installation standard requires cushion that meets the carpet maker's recommendations and says residential cushion "should not exceed 7/16 inch (11 mm)." So choose the carpet first from our carpet catalog, then match the cushion to it rather than buying the thickest pad in the store.
Luxury vinyl plank (LVP)
Many luxury vinyl plank (LVP) floors, especially rigid-core planks, float on a pad attached to the back of each plank. That pad is where the plank's sound rating comes from, and makers publish it. Tarkett's specification sheet for its ProGen plank, for example, lists a 1 mm attached foam backing and a delta IIC of 21 or better.
Add 21 to a bare 6-inch slab's IIC of 26 to 30 and you get roughly 47 to 51, before the ceiling underneath adds anything. So a thin attached pad puts a plank near the code line of 50 on bare concrete. A stricter rule usually needs more under the floor, and that extra layer should be a tested acoustic underlayment the plank's maker approves, not a second pad from the hardware store. Mannington's installation guide for its ADURA Max plank says it plainly: "Additional pad is not recommended."
Hard floors also add a sound carpet doesn't make: the click of heels, dog nails and dropped keys. Rugs with pads over the busiest paths soften it. When you compare planks in our luxury vinyl catalog, check each spec sheet for a delta IIC and each installation guide for its underlayment rules.
Engineered hardwood
Engineered hardwood, like the engineered oak and maple in our hardwood catalog, can meet a condo rule when it goes down as a tested sound system. The NWFA's guidelines show it floated over an acoustic underlayment or glued over one bonded to the subfloor. Some wood flooring adhesives reduce sound on their own, too. Solid hardwood, which is nailed, needs a floated plywood subfloor over the sound layer.
Two NWFA rules protect the rating. Never nail through an acoustic underlayment, which the association says "will compromise the specified IIC or STC ratings." And don't add an acoustic underlayment under an engineered floor that already has one attached, unless the flooring maker recommends it.
Laminate
Laminate floats, usually on an attached pad, so it works like LVP against a sound rule. The tested system counts, and the maker's guide decides what else can go under it. Provenza's MaxCore laminate, for example, has an attached underlayment pad and is designed to float. Its guide requires at least a 1/2-inch expansion gap at all walls and fixed objects, and it says skipping its requirements will void the warranty.
Tile in condo kitchens and bathrooms
Tile needs its own sound layer in a condo because it's the hardest surface you can put down. ASTM notes that sharp, high-frequency impact sound "is primarily determined by the characteristics of the floor topping." The layer made for tile is a bonded sound reduction membrane, covered by ANSI A118.13, the national standard listed by the Tile Council of North America. Ask for the membrane's test on a floor like yours, and plan for the added height where tile meets the next floor.
Choosing an underlayment for a condo floor
Choose an underlayment by the number your rule asks for and by what your flooring maker allows, not by the material's name. The NWFA lists cork, recycled rubber, cork-rubber blends, foam pads, recycled fiber and peel-and-stick membranes among acoustic underlayments. It says the right one depends on "the type of flooring used, type of substrate, concrete thickness, ceiling suspension, framing structure, and the entire floor/ceiling assembly."
How to compare rubber, cork, felt and foam
Rubber, cork, felt and foam can each be part of a floor that passes, so compare tested numbers rather than materials. On concrete, compare delta IIC from the same ASTM test. In a wood-framed building, compare full IIC tests on wood-framed floors. Sellers of each material publish comparisons that favor their own product. Treat a seller's ranking as a claim, and ask for the test report behind it.
Why a thicker underlayment isn't automatically quieter
A thicker pad isn't the goal. Under a floating floor, the NWFA says the underlayment "should have a published compression resistance and density that meets all minimum requirements of the flooring being installed over it." Carpet cushion has its own cap of 7/16 inch in homes. Every layer also adds height where the new floor meets tile or an entry door. Our guide to floor transitions and thresholds shows how to plan for it.
Replacing an old hard floor that sits on a sound mat
If you're replacing an old hard floor, find out what's under it before tear-out. The NWFA says choosing the right sound system for a floor change-out in an existing building is "just as vital" as in new construction. So if the old floor sits on a sound mat, plan a new sound layer at least as good, and name it in your approval request. Tearing out a mat without replacing it can leave the new floor louder downstairs than the old one.
Installation details that protect the rating
How the floor goes in can undo a good rating. The NWFA's guidelines for sound-rated wood floors call for these details, and they're worth asking about for any floating floor:
- A perimeter isolation strip around the room before the underlayment goes down
- No hard contact between the floor and any wall, pipe or cabinet
- Baseboard fastened to the wall, not the floor, with a small gap over the flooring
- No nails through the sound layer
Some associations write in more. The NWFA mentions CC&Rs that call for "acoustical foam in the expansion space as well as acoustical sealant."
What to put in your HOA flooring approval request
An approval request goes fastest when it answers the rule's exact question with documents, so the board can say yes without guessing. It follows the order the NWFA gives installers. Find the IIC, delta IIC or STC requirement first, then choose a flooring and underlayment that meet it, and install them as one system. Include:
- The rule you're meeting, with its number and whether it's a lab or field number
- The flooring's name and specification sheet
- The underlayment or sound system and its test report, which describes the tested floor
- How the floor will be installed (floated, glued, or nailed over a floated subfloor) and which rooms it covers
- The installer's name, the schedule, and how halls and elevators will be protected
- Your association's request form, signed
Ask the manager how often the board meets and how long a review usually takes, and don't book the install until the approval is in writing.
E&A Pro Flooring is a locally owned flooring company in Bellevue that serves condo and townhome owners in Kirkland. We install LVP, hardwood, laminate, carpet and tile. At a free in-home estimate, we can check a floor and underlayment against your rule before anything is ordered.
Install day in a Kirkland condo building
Condo installs run on the building's rules as much as the installer's, so settle the logistics with your manager ahead of time. Tear-out is the loudest day of the job and the one your downstairs neighbor will remember. Before the crew arrives:
- Reserve the elevator and loading area if your building requires it
- Confirm the hours when noisy work, like tear-out and cutting, is allowed
- Agree on how halls, elevator walls and door frames will be protected
- Arrange how the old flooring leaves the building
- Give your downstairs neighbor the dates
E&A Pro Flooring's services include job supervision and coordination, plus subfloor repair if tear-out turns up damage.
If your downstairs neighbor complains after the floor goes in
A complaint after installation usually comes down to a field test. In a field test (ASTM E1007), a tester runs a standard tapping machine on your floor and measures the sound in the room underneath. The result includes every path sound takes through the building, which is why a field number runs lower than a lab number for the same floor. For new buildings, the code's field line is 45.
Your association's documents decide what happens next, including who arranges and pays for a test. Keep the approval letter, the product and underlayment specs and the installer's records together. Meanwhile, rugs with pads over the busiest paths and felt pads on chair legs cut the impacts neighbors notice most.
Kirkland condo flooring questions, answered
What IIC rating should an HOA require for flooring?
There's no single right number, but a good rule names one and says whether it means a lab or a field result. The code's line for new buildings is IIC 50 in a lab or 45 in the field. The NWFA notes that association standards are often stricter.
A product manager writing in the NWFA's magazine urged associations to reconsider bylaws "that demand unrealistic acoustic performance," since results depend on how the building was built. A rule that accepts delta IIC for concrete buildings and full-floor or field tests for wood-framed ones matches how the tests work.
Can an HOA require a specific underlayment?
Yes, an HOA can require a specific underlayment if its governing documents say so. The NWFA tells installers to check the CC&Rs for a specified sound system before bidding. If the named product doesn't suit your floor, ask the board in writing whether a tested system with an equal or better rating is acceptable.
What happens if I install a floor without HOA approval?
It depends on your association's documents, but it won't stay private. When you sell, Washington's resale certificate has to disclose alterations the association knows break its rules. And a neighbor's complaint can lead to a field test. Getting approval first costs far less than redoing a finished floor.
Can area rugs satisfy an HOA sound rule?
No, not unless the rule says so. A rule written as an IIC number is met by the installed floor, underlayment and ceiling, because that's what the test measures. Rugs with pads still soften impacts where they lie, which helps with a neighbor even when they don't count toward the number.
What should I bring to a flooring estimate for a condo?
Bring your association's flooring rule and request form, plus the spec sheets for any floor you like. Also bring what you know about the building, such as whether it's concrete or wood-framed and whether neighbors have complained about sound before. With those, the floor, underlayment and installation method can be matched to the rule before anything is ordered.
Settle the rule first and the floor second, and a condo floor goes in without surprises. If you're planning new floors for a Kirkland condo or townhome, request a free in-home estimate and bring your association's rules. We'll show you floors and underlayments that fit them.
