Insulation
Rockwool insulation installation
Firm, fire-resistant mineral wool batts for walls, floors and spots near heat or moisture.
Learn more →Soundproofing insulation · Seattle & Puget Sound
Quieter rooms start inside the walls.
Hollow walls and floors carry sound from room to room. Dense mineral wool in those cavities, plus sealed gaps, cuts a lot of it. We'll also tell you honestly what insulation alone can't do.
- Mineral wool in walls and floors
- Home offices, media rooms and bedrooms
- Straight answers on what insulation can do
Mineral wool soundproofing insulation in a home office wall · Tukwila, WAThe problem
Why your house carries sound
Most interior walls are two sheets of drywall on studs with nothing in between. That empty cavity works like a drum. Voices, TV audio and footsteps hit one side, the drywall vibrates, the air inside carries it across, and the other side passes it into the next room. Floors between levels do the same thing. The joist bays above a kitchen or living room are usually empty, so every footstep upstairs comes straight through the ceiling.
Filling those cavities with dense insulation absorbs a good share of the sound bouncing around inside, so less of it reaches the other side. It's one of the most cost-effective first steps toward a quieter room. It's also only one of the steps. Real soundproofing combines absorption with added mass, decoupling the two sides of the wall and sealing every gap. We're upfront about which of those your room needs.
Warning signs
Rooms that benefit from soundproofing insulation
These are the spaces people most often ask us to quiet down.
- SIGN 01
Home offices
Video calls next to a kitchen, a playroom or a busy hallway. Insulated walls keep household noise out and your calls in.
- SIGN 02
Media rooms and music spaces
Movie audio and practice sessions carry through hollow walls. Mineral wool cuts the mid and high tones that travel most.
- SIGN 03
Bedrooms by a busy street
Traffic from arterials and highways comes through exterior walls, windows and the attic. Insulation helps where the walls are open.
- SIGN 04
Floors between levels
Footsteps, voices and the TV below come through empty joist bays. Insulation between the joists softens the airborne part.
- SIGN 05
Bathrooms near living spaces
Plumbing noise and fan hum through a shared wall is a common complaint. Insulating that wall during a remodel helps.
- SIGN 06
ADUs and rooms over garages
Living space over a garage, workshop or rental unit benefits from insulated floors and walls between the two uses.
Proof of work
See the difference
Drag the slider to compare. Illustrations of typical results on homes like yours.
BeforeAfterHow we do it
How we approach a soundproofing job
We start by finding where the sound actually comes through.
- 01
Find the sound path
We look at the room, the walls and the floors around it, and where the noise is coming from. Is it voices through a shared wall, footsteps from above, or traffic from outside? Sound takes the easiest path, which is often a gap, a door, a duct or a window rather than the wall itself.
- 02
Tell you what will help
We explain what insulation will do in your room and what it won't. If the noise is mostly coming under a hollow-core door or through a shared duct, we say so. If you want more than insulation, we explain what added mass, decoupling and sealing would mean for that wall and how we can plan it.
- 03
Open or access the cavity
Insulation has to get inside the wall or floor. The cleanest time is during a remodel or when drywall is already off. Floors between levels are reached from the ceiling below. We plan this with you so the work happens in the order that makes sense for your house.
- 04
Fill with mineral wool
We fit dense mineral wool batts into every bay, cut snug to the studs or joists and notched around boxes and pipes so there are no open pockets. Gaps undo much of the benefit, so each bay is filled edge to edge at full thickness rather than squeezed or left loose.
- 05
Seal the leaks
Sound moves through any air gap. We seal around top and bottom plates, pipe and wire penetrations and electrical boxes with sealant before the wall closes. We photograph the filled cavities so you have a record of what's behind the drywall once it goes back up.
What you get
Soundproofing insulation spec sheet
| Main material | Mineral wool (rockwool) batts |
|---|---|
| Typical areas | Interior walls, floors between levels, ceilings, attic floors |
| Rooms | Home offices, media rooms, bedrooms, bathrooms, ADUs |
| Fitting | Friction-fit, edge to edge, notched around boxes and pipes |
| Gap sealing | Plates, penetrations and electrical boxes sealed |
| Access | Best during remodels or with drywall open |
| Beyond insulation | Mass, decoupling and door upgrades explained and planned |
| Photos | Filled cavities photographed before drywall goes back |
Diagram
- 1Mineral wool absorbs
- 2Added mass blocks
- 3Decoupling breaks paths
- 4Sealed gaps
- 5Solid-core door
- 6Low sounds need more
Compare
Insulation alone or a full sound assembly
Insulation is the first layer of soundproofing. Here's what the rest adds.
| Factor | Mineral wool in the cavity | Full sound assembly |
|---|---|---|
| What it includes | Dense insulation filling the wall or floor | Insulation plus added mass, decoupling and sealed gaps |
| Voices and TV | Noticeably reduced | Reduced further |
| Bass and footstep thuds | Some improvement | Better; low sounds need mass and decoupling |
| Disruption | Low during a remodel or with walls open | More: added drywall layers and framing changes |
| Best for | Most offices, bedrooms and bathroom walls | Media rooms, music spaces and shared walls |
Puget Sound homes
Noise in Puget Sound homes
Plenty of homes in the region sit close to steady noise. Houses along I-5, I-405 and SR 520, near Aurora Avenue or the busy arterials of Bellevue and Lynnwood, hear traffic all day. Neighborhoods in Burien, Des Moines, Normandy Park and SeaTac sit under the flight paths. In those homes, outside noise comes through the attic and exterior walls as well as the windows. A deep attic layer and insulated walls take some of the edge off, though windows and gaps usually matter just as much.
Inside, the biggest change has been the home office. More people work from bedrooms, dens and converted garages in Seattle and on the Eastside, often next to a kitchen or a kids' room. Newer townhomes and many 1970s through 1990s houses have thin interior walls with empty cavities. When you're already remodeling, adding an ADU or opening walls for other work, filling those walls with mineral wool is a small add that makes a noticeable difference, and it's far easier than opening the same walls again later.
Pricing
What shapes the price
Soundproofing jobs vary more than most. These factors decide the scope.
- FACTOR 01
Walls and floors involved
How many walls, ceilings or floor sections we're filling, and their size.
- FACTOR 02
Access to the cavities
Open walls during a remodel are quick. Opening finished walls or ceilings adds work and patching.
- FACTOR 03
Insulation only or full assembly
Mineral wool alone, or combined with added drywall, decoupling and door changes.
- FACTOR 04
Gaps and penetrations
The number of outlets, pipes, ducts and openings that need sealing.
- FACTOR 05
Related insulation work
Attic or crawl space insulation done at the same time can share setup and help with outside noise.
We had rodent problem in our house. Also our house had bare minimum insulation in some places. Isaac was very helpful, he also took some photos of the attic and crawl space. They gave me a reasonable quote for rodent proofing and insulation. Their crew was on time and finished the job in two days. Really appreciate their hard work.
FAQ
Soundproofing insulation: questions we hear
Still unsure? Call (800) 674-4933 and talk it through with us.
Does insulation really soundproof a room?
It reduces sound, but on its own it doesn't make a room soundproof. Dense insulation absorbs sound inside the wall cavity, which cuts voices and TV noise noticeably. Blocking more sound, especially bass and footsteps, also takes added mass, decoupling the two sides of the wall and sealing every gap.
What is the best insulation for soundproofing?
Mineral wool, also called rockwool, is our usual choice. It's denser than standard fiberglass, which helps it absorb more sound, and it fits firmly in the cavity without sagging. It's also non-combustible. Fiberglass batts help too, just not as much for the same wall thickness.
Can you add soundproofing insulation without removing drywall?
Usually the cavity has to be opened on one side to fit batts properly, which is why remodels are the best time. For floors between levels, we work from the ceiling below. We'll look at your room and tell you honestly what access it needs and whether the result is worth the work.
How much quieter will my room be?
We don't promise specific numbers, because the result depends on the wall, the door, the gaps and the kind of noise. What we can say: filling hollow walls with mineral wool and sealing gaps makes voices and TV noticeably quieter. Low-frequency sound like bass and traffic rumble needs more than insulation.
Will insulating the attic block outside noise?
It can help. A deep attic layer absorbs some of the noise coming through the roof, like aircraft overhead, heavy rain on the roof or traffic sound. Windows, doors and gaps in exterior walls often let in more, so we look at the whole room before telling you what to expect.
Do you install soundproofing beyond insulation?
Insulation and gap sealing are the core of what we do. For rooms that need more, like added drywall layers, decoupled framing or door changes, we explain the options plainly and can plan that wall work through our home remodeling services, so it happens alongside the insulation.
Related services
Often done together
Insulation
Batt insulation installation
Fiberglass and mineral wool batts for crawl space floors, knee walls and open walls, fitted bay by bay.
Learn more →
Attic services
Air sealing
Sealing top plates, can lights, bath fans and chases from the attic side before new insulation goes in.
Learn more →
Insulation
Attic insulation
How much insulation your attic needs, which material fits, and what it takes to get there.
Learn more →Let's see what's going on up there.
Book a free inspection. We'll photograph your attic and crawl space and walk you through what we find, before you decide anything.