We have a remodel we are on where there is a 2nd level kids' room that is used for gaming, hang-out, etc. The homeowners want to cut down on sound through the floor. We don't have the opportunity to put anything in the walls...just the underlayment for the floor.

Any ideas for methods to cut down on sound transfer? I'm sure that both high and low frequency are desired. We had used Dynapad on a job before and it did a good job but I'm interested to know if others here have better ideas (Quietboard, other materials, etc.).

Thanks!

Multiple layers of materials are used to diminish sound transference. Challenge will be multiple issues:
1. If there is hvac vents shared, that will pass sound
2. There will be some frequencies that will pass louder than others with multiple layers. Carpeting will help. Padding will help. Insulation will help between the floors.
3. Hiring a company that does this sort of thing takes you out of the discussion, and might be worth considering
4. What is the home owner expecting?

Absorbent padding is only partially effective.

Set expectations. You can improve things but you will not eliminate the sound transfers. If you overpromise, the client will be unhappy with you.

floor:

Value: Layer of 3/4 underlayment with Serena underlayment then 3/4" T&G plywood then flooring

Next level: Add another layer of 3/4" T&G with green glue between them.

Ceiling:
Bang for the buck: use 2 layers of 5/8" drywall.

Next level: add a layer of green glue between the sheet rock

Next level: above but isolation clips and resilient channel

Ultimate: build room within a room construction.

HVAC: flexible ducts if possible with liners. Or liners for metal ducts. Wrap metal ducts in mass load vinyl.

Bob's suggestion sounds like what I saw used in a high-rise residential building several years ago. I'd try to find someone who builds such buildings, to see what they recommend. The residents swore they never heard anything from the floors above and below.

By underlayment are you referring to anything on top of existing sub floor?

Can you remove the subfloor and add safe and Sound insulation into the floor joists below?

If so then I would start there and follow Bob's recommendation of multiple layers of sub flooring, first layer glue and screwed to joists, next layer either with some type of glue/rubber separation so it will help absorb more of the sound (ensuring you lay second layer opposite of first to minimize overlapping joints), then a good thick carpet padding then a thick carpet.

Adding sound absorbing materials to walls will help as well. Any windows use floor to ceiling drapes as opposed to inset window blinds, try and get some cool canvas artwork to add to walls as it will also help any sound transfer.

Thanks for the ideas all!

Please let us know what you did and how well it worked!

I have used Quietrock between to bedrooms to great effect.

You could use it on the ceiling and use Dynabox for the lights, etc

Best practice, isolate one floor from the one below. That's not always possible, so the recommendations listed will help, but not completely. It would be better if the place had concrete floors, but....

Any transitions for the HVAC ducts connected to the new space should be flexible- the transmission along steel is extremely efficient and it travels very fast. In addition to the flexible transitions, baffles made of rigid, sound absorbing duct material will help to block some of the remaining sound in the ducts.

When possible, don't allow straight duct connections between the air handler and a room or between rooms. Insert a bend and baffle along the way. This will decrease efficiency and must be incorporated in the overall design, but it will significantly reduce noise transmission. Yes, this will increase costs, and if the extra trouble makes the aircon contractor too grumpy, try to change contractors.