Dear Bob and Betsy,
I am responsible for reviewing and approving architectural modification requests for our condo association. Our documents state that our floors must have both the IIC and STC at 55 or higher. We have 6 inch solid concrete floors with no acoustical ceilings. What are the best underlayment for condos and apartments that meet our requirements? Thank you, Fred
This is a really important question! For those living in apartments or condos, and having the luxury to be able to renovate them, you will have to abide by the standards set forth by your condo/apartment association or HOA. One of these things that is commonly overlooked is the noise your neighbors underneath you will hear! We have compiled more information for you to help to decide what’s best for you. Cheers! Bob & Betsy
First, let’s talk about what exactly underlayment is, and what it is used for. If your apartment or condo is using a floating floor, like laminate or engineered hardwood, underlayment is always required. If the owner decides on a vinyl flooring, underlayment may not be necessary depending on the type of vinyl plank selected. Your HOA may need to specify instructions for each type of flooring.
Underlayment is a thin, foam or felt layer that is installed above the subfloor and below the floating floor. The types and thicknesses of underlayment will depend on a few factors. You can learn more about underlayment here.
Underlayment gives a few benefits to a homeowner, and even a neighbor underneath you. The main benefits of underlayment include:
- Comfort underfoot (especially under concrete)
- Moisture barrier
- Smoothing out slight imperfections in the subfloor
- Sound dampening
- Thermal properties (depending on the underlayment)
What Does IIC and STC Ratings Mean?
Now, let’s talk about the IIC and STC ratings. While looking at underlayment for your laminate floor, you may come across IIC-STC with a number next to them. These are ratings that tell you how well the underlayment will dampen sound. The higher a number is following these letters, the less noise will be transmitted. The effect of this is mostly noticeable in rooms underneath the room in which the underlayment and laminate are installed. This is why many apartment buildings, commercial offices buildings, and condo associations require a minimum rating where sound is concerned. The general ratings are as follows:
- IIC-STC 70 Virtually Sound Proof
- IIC-STC 60 Superior Sound Proofing
- IIC-STC 50 International Building Code
- IIC-STC 40 Sound Proofing below most codes
(STC) Sound Transmission Class from the American Society for Testing and Materials (ASTM) E336/E413 and (IIC) Impact Isolation Class ASTM E492/E989 ratings are measured in decibels reduced for certain types of sound. The STC rating pertains to airborne noise, such as voices, radio, television, etc. The IIC rating measures impact sounds, such as footfalls, dropped objects etc.
The transmission of these sounds through floor/ceiling assemblies (such as those found in multi-level homes and apartments) will be inhibited by underlayment with higher IIC and STC ratings. The International Building Code (IBC) states that all multi-family buildings must have a minimum sound insulation rating of STC 50 and IIC 50, but yours may vary. Check with your condo/apartment association to get the exact numbers, so you make your minimum requirements.
Which Underlayments Make The Cut?
Some premium underlayment will have ratings that exceed these strict IIC and STC ratings made by most condo/apartment associations. Brands such as Kronoswiss, Roberts, Quick Step, and Floor Muffler are all perfect underlayment for your condo or apartment. Let’s take a look at the wide selection available to you!
Bestlaminate offers a superior felt option that includes a moisture barrier, cushion and sound dampening. This 3mm felt underlayment is available in a 100 sq.ft. roll and perfect for any floating floor, both laminate and engineered hardwoods. The STC rating is 66db and IIC rating is 69db, exceeding most requirements for sound dampening. This roll is made from recycled fibers and includes a self-adhesive overlap for easy installation!
This underlayment is manufactured by Roberts. It is 3mm thick and comes in either 100 sq.ft. rolls, or 360 sq.ft. jumbo rolls, which are perfect for contractors looking to cover many apartments quickly. The STC Rating is 66db, and the IIC Rating is 67db. It inclused a 3″ overlap and self-adhesive strip to make installation even easier. This underlayment also has a pre-attached vapor barrier to protect floors from moisture escaping concrete subfloors. The recycled fiber construction adds extra insulation and cushioning to make both residents, and downstairs neighbors happy!
This underlayment is manufactured by Quick-Step in the USA. It is 3mm thick and comes in 100 sq.ft. rolls, measured 40in x 30ft. STC Rating is 67db and the IIC Rating is 68db, well above the minimum requirement for apartments and condos!
This premium underlayment is 3mm and comes in rolls of 100 sq.ft. The Silent 3-in-1 underlayment is great for use over concrete and wood sub-flooring. It can be used underneath laminate flooring, engineered, and even solid hardwood flooring! The STC Rating is 67db and the IIC Rating is 68, perfect for condos and apartments! This unique underlayment retains 96% of it’s original thickness after 7 days, compared to only 57% by leading 3-in-1 foam products. The microbeads in the underlayment allow for maximum bounce back and circulation so no mold or mildew gets a chance to grow! A great, long-lasting underlayment.
Kronoswiss Provent Silent Vapor 3-IN-1 Underlayment
This is another 3-in-1 underlayment, but it’s manufactured by the flooring company Kronoswiss. These rolls are 3mm thick and come in rolls of 215.28 sq.ft., bigger than the average sized roll! The STC rating is 67 and the IIC Rating is 71, which gives you even better noise absorption than the leading premium underlayment! Kronoswiss’ MicroPumping System provides air circulation underneath the boards when you walk on it, inhibiting the growth of mold and mildew on your subfloor! This underlayment is also non-allergenic, so there will be no issues for residents with asthma or allergies!
Now, for the cream of the crop, the grand-daddy of all sound-reducing underlayments, Floor Muffler. This underlayment is STC Rated 73db and IIC Rated 74db. It will be hard for your downstairs neighbors to hear anything coming through their ceiling! This underlayment comes in 100 sq.ft. rolls and 700 sq.ft. jumbo rolls, making this a contractor’s dream! It’s suitable for cement and wood subfloors, so it can almost be installed over anything! It even comes with a self-sealing strip to make laying it out as quickly as possible. To top it all off, it’s made in the USA!
We hope we have given you plenty of choices of underlayment to meet your condo/apartment association IIC and STC rating requirements that fit your needs and budget. If you have any questions, please write us in the comments below or call us at 1-800-520-0961!