Building Envelope SolutionsCall or text (347) 200-5089 for a K-13 quote. Send the drawings or the ceiling area and we’ll price it.
What K-13 is
K-13 is a spray-applied insulation made from cellulose fibers. It is sprayed straight onto a ceiling and left exposed as the finished surface, with no tiles or drywall under it. The result is a seamless, textured ceiling that does two jobs:
- It absorbs noise. Hard ceilings bounce sound around a room. K-13 soaks it up, so a busy office, restaurant or gym is quieter and speech is easier to follow.
- It insulates. It adds R-3.7 for every inch of thickness, and because it is sprayed in place it has no seams or gaps.
K-13 is made by International Cellulose Corporation. Its fibers are more than 80 percent recycled material, and the manufacturer’s data sheet says it contains no asbestos, mineral fibers or glass fibers.
Where K-13 is used
Any large room with a hard, exposed ceiling is a candidate:
- Open offices and lobbies where the ceiling is left exposed and the room echoes.
- Parking garages. Sprayed on the underside of the slab, it insulates the floor above and quiets the garage.
- Restaurants, cafes and bars where noise builds up over hard surfaces.
- Gyms, courts and indoor pools.
- Schools, auditoriums and houses of worship.
- Mechanical rooms and studios.
- Lofts and converted buildings with concrete or metal deck ceilings.
It bonds to concrete, metal deck and other prepared surfaces, and it follows beams, ducts and odd shapes that a tile ceiling cannot.
K-13 by the numbers
These are the manufacturer’s published figures, from its February 2025 data sheet.
| What | Figure |
|---|---|
| Insulation | R-3.7 per inch (ASTM C 518) |
| Thickness | Up to 5 inches in one application, with no mechanical support |
| Sound absorption on a solid ceiling | NRC 0.80 at 1 inch, 0.90 at 1.5 inches, 1.00 at 2 inches (ASTM C 423) |
| Fire rating | Class 1, Class A: flame spread 5, smoke developed 5 (ASTM E 84) |
| Standard colors | White, light gray, gray, tan and black, plus custom. See the colors |
| Light reflectance | 84 or higher in white, so a white ceiling keeps a room bright |
| Indoor air | UL GREENGUARD Gold certified |
| New York City | The data sheet lists NYC acceptance number MEA 65-96-M |
NRC is the share of sound a surface absorbs. An NRC of 0.80 means the ceiling absorbs about 80 percent of the sound that reaches it.
Sources: International Cellulose Corporation, K-13 and its K-13 data sheet.
K-13 colors
K-13 comes in five standard colors, and the manufacturer can match a custom color. The color is in the material itself, so there is nothing to paint afterwards.
How to choose:
- White reflects the most light and keeps a room bright. It is the usual choice for offices and garages.
- Black makes the ceiling, ducts and pipes disappear. It is common in restaurants, bars, theaters and studios.
- Grays and tan sit between the two.
Colors on a screen are only a guide. Ask us for a sample before you decide. The color changes the price.
The K-13 product line
K-13 is one of a family of spray-applied finishes from the same manufacturer. Tell us which one your drawings call for, or tell us the room and we’ll say which fits.
| Product | What it is | Where it fits |
|---|---|---|
| K-13 | The standard. A natural texture, sprayed from ¾ inch up to 5 inches thick. R-3.7 per inch | Exposed ceilings that need noise control, insulation or both |
| K-13 High-R System | K-13 sprayed in two layers over pins and wire lath, up to 10 inches thick and about R-37 | Parking garages, event halls, metal buildings and other ceilings that need a high R-value |
| K-13 Special Blend | A blend of K-13 and SonaSpray “fc” with a finer texture | Ceilings that need K-13’s performance with a more refined look, indoors or on covered parking decks |
| Protek-13 | A protective coating sprayed over K-13. It resists scuffing and keeps dust and dirt from building up | Garages, loading areas and industrial spaces. Not for surfaces that get rained on or pressure washed |
Related finishes from the same manufacturer:
| Product | What it is | Where it fits |
|---|---|---|
| SonaSpray “fc” | A finer acoustic texture, sprayed ½ inch to 1 inch thick. At ½ inch on a solid ceiling it cuts excess noise by about 65 percent | Offices, schools, restaurants, hotels and houses of worship where looks matter most |
| SonaKrete | Sprayed in thin layers and troweled smooth, like plaster, ¼ inch to ¾ inch thick. NRC 0.65 at ½ inch | Historic renovations, domes, arches and concert halls |
| Ure-K | Sprayed over spray foam as the 15-minute thermal barrier the building code requires. Adds R-4.5 at 1¼ inches | Exposed spray foam in warehouses, garages and commercial buildings |
Sources: the manufacturer’s pages for K-13, the High-R System, Protek-13, SonaSpray “fc”, SonaKrete and Ure-K.
Example: an office floor in Midtown Manhattan
A full office floor in a Midtown tower, sprayed in white. We covered the beams, columns, windows and ducts first, then sprayed the ceiling bays between the beams.
How we install K-13
K-13 on our jobs is installed by a manufacturer-licensed applicator.
- We look at the ceiling. We check what it is made of, its condition and how thick the K-13 needs to be for the noise or insulation target.
- We cover everything else. Windows, walls, floors, beams that stay clean, ducts and sprinkler heads are masked with plastic and tape.
- We spray. The cellulose fibers are fed through a machine and a hose. At the nozzle they mix with a water-based adhesive and bond to the ceiling. We build it up to the thickness in the spec.
- We clean up. The masking comes off, the floor is cleared, and the ceiling is left to dry.
How thick should it be?
It depends on what you need it to do.
- For noise: 1 to 2 inches covers most rooms. On a solid ceiling the manufacturer’s tests show NRC 0.80 at 1 inch and 1.00 at 2 inches.
- For insulation: thickness sets the R-value. Three inches is about R-11 and five inches is about R-18.5.
- For both: we size it to the larger of the two.
If an architect or engineer has written a spec, we install to it.
K-13 or spray foam?
They do different jobs. Spray foam is the stronger insulator and air seal, but it usually has to be covered. K-13 is made to stay exposed as the finished ceiling, and it is the one that absorbs sound. For noise between apartments or floors, see soundproofing with Rockwool.
What K-13 costs
The price depends on the ceiling area, the thickness, the color, the ceiling height and how much has to be masked. Color changes the price, and so does working at night or in an occupied building. Call (347) 200-5089 or send us the details and we’ll give you a number.
Where we work
We install K-13 in Manhattan, Brooklyn, Queens, the Bronx and Staten Island, and on Long Island. See our service areas and our other commercial insulation work.
Common questions
What is K-13 insulation? K-13 is a spray-applied cellulose insulation made by International Cellulose Corporation. It is sprayed onto a ceiling and left exposed, where it absorbs noise and insulates.
What is K-13 used for? Mostly exposed ceilings in large rooms: open offices, parking garages, restaurants, gyms, schools, auditoriums and mechanical rooms.
What is the R-value of K-13? R-3.7 per inch, by the manufacturer’s data sheet. Three inches is about R-11.
How much noise does K-13 absorb? On a solid ceiling the manufacturer’s tests show an NRC of 0.80 at 1 inch and 1.00 at 2 inches.
Is K-13 fireproofing? No. K-13 is rated Class A as an interior finish, but it is not a fireproofing material for steel. Steel that needs a fire rating gets a separate fireproofing product.
What colors does K-13 come in? White, light gray, gray, tan and black are standard. Custom colors can be matched.
What is the difference between K-13 and SonaSpray? Both are sprayed cellulose finishes from the same manufacturer. K-13 goes on thicker and insulates as well as absorbing sound. SonaSpray “fc” is a thinner, finer texture used mainly for sound and looks.
What is the K-13 High-R System? It is K-13 sprayed in two layers over pins and wire lath, up to 10 inches thick, for ceilings that need about R-19 or more.
Can K-13 go on a parking garage ceiling? Yes. Parking garages are one of its common uses. On the underside of the slab it insulates the floor above.
Does K-13 need a ceiling under it? No. It is the finished surface.
Do you install K-13 in occupied buildings? Yes. We mask the work area and schedule around the building. Call us to plan it.
K-13 is a trademark of International Cellulose Corporation.