Does carpet tile satisfy an impact-sound requirement by itself?
Not as a rule. Some assemblies include carpet, and some require a mat under a hard surface. Follow the tested assembly named in the documents.
Impact sound
When the underlayment is its own quantity
Worked mat area with a doorway stop
Illustrative rooms. No acoustic rating is claimed.
- Unit living area to receive the specified mat: 710 sq ft. Bathroom excluded by the spec.
- Mat order follows the mat roll or sheet coverage, not the flooring carton. If the mat roll is 100 sq ft, 710 ÷ 100 = 7.1, so 8 rolls, and the partial roll is shown.
- The flooring above it still uses its own carton math.
- One doorway down to a corridor without the mat needs a reducer. Measure that doorway.
Acoustic performance is a floor-ceiling assembly, not a flooring SKU. If the documents require a mat under the finish, the mat has area, seams, and a perimeter detail. If they do not, adding a mat because the room is an apartment is an assumption you should label.
Assembly versus product
- An IIC or STC figure, when the documents state one, belongs to a tested assembly: slab, mat, underlayment, and finish. Swapping the finish can void the tested assembly. The takeoff should name the products in the specified assembly rather than promise a rating.
Measure the mat, then the finish
- The mat area usually matches the finish area, but seams, tape, and the edge at the wall are mat accessories. A product with an attached pad does not automatically get a second mat. Check the instructions before you buy both.
Stairs and transitions
- Mats often stop at a doorway where the adjacent room has a different assembly. The reducer has to absorb the height change. That reducer is a linear-foot item caused by the mat, and it is easy to miss if you only duplicate the floor area.
Related reading: what sits under the finish, finish schedules, plank over a mat.
Questions this page answers
Should every multi-family floor include a mat in the bid?
Only when the finish schedule, the acoustic section, or an addendum requires it. Otherwise list it as an excluded alternate.