Sound deadening underlayment?

[Adkroot]

I’m not expecting anything close to the sound deadening quality of insulation between floor joists, but I’m wondering if any of the advertised sound deadening underlayments I’m seeing online help much at all with quieting the sound of footfall on the second floor.
I’ve got wide-spaced timber framed joists and plank subfloor that’s also the finished first floor ceiling so I’m not closing in/using a drop ceiling. Putting down hardwood over the subfloor and wondering if something other than rosin paper might help. Thanks

 

[duneslider]

I’m not expecting anything close to the sound deadening quality of insulation between floor joists, but I’m wondering if any of the advertised sound deadening underlayments I’m seeing online help much at all with quieting the sound of footfall on the second floor.
I’ve got wide-spaced timber framed joists and plank subfloor that’s also the finished first floor ceiling so I’m not closing in/using a drop ceiling. Putting down hardwood over the subfloor and wondering if something other than rosin paper might help. Thanks

So, the issue is most of the underlayments really aren't great for under hardwood. I think you would probably be okay with something super dense like MLV (Mass Loaded Vinyl). This leads to other issues too with a proper wood floor install. Typically, once you get too close to walls to use the nailer you switch to a brad nailer and glue which the glue won't work with an underlayment. So, idealy in this sort of situation you would have the subfloor, add a sound deadening underlayment, another layer of plywood, then staple your wood down. Also, rosin paper is pretty much pointless and a waste of time/money.

That said, mass helps prevent sound transmission and even just adding the hardwood will be better than what you have now. Another option is to do an acoustical adhesive under the hardwood which would work good in your situation. Depending on the wood and the width you are planning on gluing the wood may be advisable anyway.

 

[rlitman]

I think there are a few issues here, but we should start with setting expectations where they belong. Low.

The all wood barrier between the floors is going to be pretty transparent to sound. Adding layers of wood doesn't buy much.

The MLV layer is a good idea. It will go pretty far to reduce transmission of higher frequency sounds from passing (the sharp impulse of hard soled shoes clacking on the floor; spoken words; some TV noise), but not do much to reduce low frequency noise (shoe thumping). Advertized underlayments are tested as systems with specific flooring. Often vinyl, because vinyl flooring itself does a lot to soften the impulse of shoe impact, and then release the spread out pressure it into the underlayment. I don't think that's going to buy anywhere near as much with hardwood. If it matters that much, an engineered floor might be better for noise.

Also, is it possible to get construction adhesive between the plank subfloor/ceiling and the joists? I'm guessing not, but I had to ask. Can you at least screw the planks down to ensure they're not going to squeak or impact the joists?

 

[duneslider]

I think there are a few issues here, but we should start with setting expectations where they belong. Low.

The all wood barrier between the floors is going to be pretty transparent to sound. Adding layers of wood doesn't buy much.

The MLV layer is a good idea. It will go pretty far to reduce transmission of higher frequency sounds from passing (the sharp impulse of hard soled shoes clacking on the floor; spoken words; some TV noise), but not do much to reduce low frequency noise (shoe thumping). Advertized underlayments are tested as systems with specific flooring. Often vinyl, because vinyl flooring itself does a lot to soften the impulse of shoe impact, and then release the spread out pressure it into the underlayment. I don't think that's going to buy anywhere near as much with hardwood. If it matters that much, an engineered floor might be better for noise.

Also, is it possible to get construction adhesive between the plank subfloor/ceiling and the joists? I'm guessing not, but I had to ask. Can you at least screw the planks down to ensure they're not going to squeak or impact the joists?

rlitman makes a good point, expectations should be pretty low here...you are late to the game to be resolving sound transmission issues. At this point an acoustical glue is the really the only thing you can do and results with that will be somewhat low but it would make a minor difference. Adding any other height to the floor is going to screw up the stairs.

What you could do that would make a difference is put carpet in but I am sure that isn't what you are after.

I have wood in my house and you just have to understand that part of having wood flooring is the sound. Even in the bedroom we currently have finished in the basement adding the drywall and insulation between the joists didn't make the sound go away, it def decreased it but its still there.

Rugs also help prevent as much of the higher pitched noise clacking shoes and dropped items, and even voices. We have a fairly large rug in our master bedroom and I notice a lot less noise under that room when in the basement compared to the area under the kitchen we don't have a lot of rugs.

I would second the make sure everything is screwed down! I screwed down my entire house except my master closet, I missed that area it turns out. Wanna guess the only place in the whole house that has a squeak? Luckily, the ceiling isn't finished under that area so I can fix it from underneath (when I get around to it...

 

[billconner]

On my experience designing buildings for performing arts where nouse isolation is critical, yes those underlayments help reduce footfall noise transmisfion. Cork is pretty cheap and helps. Try a section. 4x4 or 4x8 3/4 ply, a piece of underlayment, and tap dance. Homesoat 440 also works but thicker.