soundproof existing room

[udaman]

I have a HT room upstair that need some soundproofing work or at least minimize the sound leakage to the other rooms. When I listen to music, in moderate level, the sound can be heard throughout the house. Dummy me, I should of done some research when the builder was working on the house.

Anyways, the HT room is upstair with an adjacent bedroom, vacant for now. The adjacent room is along the 13' wall (no insulation) of the HT. There are a couple of bedrooms below the HT. The HT has doube hollow doors.

From what I research so far, the first and cheapest thing to try first is to replace the door with solid wood door, add insulation seal on the door frame, add door insulated sweep at bottom and add that 'thingy' (don't know what you call it) that attaches to one of the door and seals the gap between the two doors when it's closed.

I may add insulation to the 13' wall later if it's still a problem afterwards. The HT floor may be another problem which could be costly to soundproof.

The problem is there are so many products out there that I don't know what works. I can't find the 'thingy' or the bottom door insulated sweep at Lowes or Home Depot. The quote for solid doors at Lowes is $250 by Masonite Safe n' Sound door. I bought two packs of ThermalBlend seal for the door frame but have install yet.

Attached is the pic of the HT room layout.

Appreciate any suggestion of what to do and where to buy the products online or local in Houston, TX.

[geniescience]

your diagram says it very well: a single layer of drywall is a real thin layer, and it can act resonate and reverberate like a drum or a violin case instead of dampening sound. If it's 1/2" it is lightweight too. The 5/8" thick kind is usually twice as dense!

Sound travels through that single layer, and through your hollow wall in your adjacent room, and from there it travels downwards through the hollow ceiling cavity under the subfloor, and into the entire building. It also goes through the door frame and open space around the door.

A few experiments will help you figure out how much improvement you can make initially without much work or budget. At first, any improvement sounds like a big difference. Unfortunately, ears can hear better and better as sounds diminish. You can wedge material under the door and around it, while a friend operates the sound system, and you walk around downstairs listening; you can camouflage upstairs noise with a white noise downstairs, like from a fan or air purifier. You can tack heavy fabric up in that door cranny (like a very heavy curtain) and see how much difference that makes. You want to prevent air in the room from reaching the door; any single door will reverberate and transmit sound, even a $1000 door. Then, when other members of the household agree, you have a plan they will accept. Real curtains, real door strips, etc.

On the single drywall wall, you can add sound insulating material (like heat insulation) on the attic side (which is open now), and cover it with plastic, to seal air.

A bigger project is inside the HT room, to add another layer of drywall, this time the 5/8" high density kind. Then, you can add cork wall covering like the kind they sell for sound studios.

David

[Gary Swart]

Depends on how many $$$s you want to spend. If you can bite the bullet, then having the walls pumped full of foam would be the best solution. Another possibility would entail removing the drywall, filling the space with fiberglass insulation, then re-rocking with 5/8 drywall. Maybe you could build a second wall that was filled with insulation. That would be a problem around doors and windows, but would provide a sound barrier.

[jadnashua]

It really depends on how much you want to spend.

To build a better sound dampening wall, you need to uncopuple the big panels from one side to the other. In new construction, they ususally use something like a 2x6 or even a 2x8 as the top and bottom plates for the wall, then use studs against the outer edge for each wall and wind insulation around the backs of each stud. Because of the wide plate, neither one goes to the other side and helps decouple things. If you don't want to tear your walls down, you need to isolate the wall panels.

Another technique is to use acoustic channel between two layers of drywall. The channel isolates one layer from the other.

A couple of new (relatively) products work exceptionally well, but are quite expensive (you get what yo upay for here), and they are a sandwich of lead and a few other things to lower the resonance frequency and damp the sound.

There's a couple of special rubberized adhesives you can use between the two layers of drywall that works pretty well, too.

Google soundproofing and you'll find some sites and details.

[udaman]

I really don't have much to spend on this. Want to try the least expensive suggestion to see the improvements before investing more money. Maybe spending $500 or less initially by replacing with solid doors and seals. I will DIY some bass trap using Owens Corning 703. Hopefully that will help some.

Will adding a thick rug absorb the sound a bit for the floor?

thanks for all the suggestion.

[jadnashua]

Any hole, however small will allow sound to leak. So, sealing all gaps is the first step. Don't forget the outlets and switches. Adding the sound channels and a second layer of drywall on the common wall will not cost much, and help as well. Hassle will be resetting the rug to the new wall. Caulk all gaps at the floor/wall interface with some of the soundproofing caulk. It's not cheap, but probably worth it.