another guy with another room

[chas]

I have an unfinished room in my basement that is being wasted as a storage area. It's time to claim it as a simple, super small budget theater room. I was going to wait a couple years since I don't have much money to put into it right now, but I'd rather do it a bit at a time and at least get it in a 'useable' state as soon as possible.

a crude pdf drawing is located here:
http://swbg1.tripod.com/1355_HT.pdf

This room is currently open to the utility room and the noisy HVAC unit, so I see the first step as building a wall to separate the HT from the utility room. Once this is done I will at least have a space that is quiet enough to use.

With the tight budget there will be no money for staggered studs or double drywall. I'm thinking 2X4 construction for this wall, insulated and drywalled on both sides.

1. I thought I read somewhere that for sound it's best to use different thickness drywall on each side of a dividing wall - is this correct? Should I use 1/2 inch on one side and 5/8 on the other?

2. Will regular insulation provide enough sound insulation in this wall or is there a more sound absorbing insulation?

3. I want the door in this wall to isolate the HVAC noise as well - should I use an exterior door with sill? My Home Depot has interior doors available with some sort of 'sound-core' - would that work?

Any and all suggestions for the room will be appreciated...but I'm mostly concerned with that dividing wall to start with.

The room has 8 foot ceilings with a couple of major HVAC ducts in the center that drop it down to a little over 7 feet. Since there are a lot of pipes etc. in this ceiling I'm planning on a black drop ceiling with insulation between the joists above and another layer on top of the ceiling.

Looking forward to your thoughts.
Thanks,
Chuck

[salvasol]

chas wrote:

...This room is currently open to the utility room and the noisy HVAC unit, so I see the first step as building a wall to separate the HT from the utility room. Once this is done I will at least have a space that is quiet enough to use.

3. I want the door in this wall to isolate the HVAC noise as well - should I use an exterior door with sill? My Home Depot has interior doors available with some sort of 'sound-core' - would that work?

Any and all suggestions for the room will be appreciated...but I'm mostly concerned with that dividing wall to start with.

Yesterday I read this article on a link posted by Dr.Pain (Audioholics - Reducing HVAC Noise in Theater Rooms) .... I'm not sure if you already read it but I think it can help you in your project

I can not tell you anything about insulation .. but I remember some posts that recommend to use double drywal, insulation and solid core doors

Anyways, Good Luck with your project.

[chas]

Thanks....I actually did read that article! Dr. Pain put together a great reference list....

[chas]

I've decided to go with a staggered stud wall to separate the HVAC utility room from the HT.

Also still open for suggestions on a door to this utility room - something fairly inexpensive yet decent performing for sound isolation....

[Anthony]

A couple of thing to be careful about:

One, some HVAC systems (heaters) expect to draw air to burn from the room they are in. If you seal that off too well, it won't be able to draw and efficiency will be reduced. Not an issue if you have a heat pump or a newer system that uses a double-flue to draw and exhaust air to the outside.

Two, for sound isolation, you basically have two methods of transmission: vibration and diffusion. Vibration is direct coupling of walls. Sound in one room vibrates the walls, transmits to the other side, then makes sound in the other room. The staggered stud will help here. Ideal is hat channel and rubber isolators, but man that gets expensive in a hurry. Your staggered stud and varying drywall thicknesses will help a lot. If possible, avoid any outlets on that common wall to improve isolation.

As for diffusion, that is sound through small cracks and openings. Best example is the gap under a door. It's amazing how closing a heavy door does little to lower the sound if that gap is too large. I've seen many a sound-proof room ruined by this (in one case it was a $1k door with no sweep and you could still hear a conversation on the other side).

I'm sure bpape and Ethan could elaborate more on the science (especially if I got a term wrong).

For your case, I would get a solid core interior door. You may want to try a salvage yard (not junk yard, but a place that specializes in saving old tubs, sinks, doors, cabinets, etc). A lot of times they have old doors that people buy to use as workbench tops, and they can be pretty cheap. Then use abundant weatherstripping and a good thick (or double) sweep on the bottom to seal the underside to the floor.

That should get you 80% or more of the way there. Unfortunately if you want that extra sound abatement, you are talking compression seals on a very expensive door, plus an extra layer of drywall everywhere, with hat channels . . .

the old diminishing returns thing again. Twice the cost for 5% more effectiveness.

I've dealt with this stuff before, but am by no means an expert. Like I said before, hopefully bpape or Ethan will chime in with more expert opinions.

good luck,
A

[chas]

Thanks Anthony - great thoughts. Fortunately there is another utility room on the other side of the HVAC unit and it does have a fresh air intake line.

The door suggestion is a good one. I'm not looking for total all-out sound isolation...just a reasonable quiet room. But I do plan to use acoustic caulk on all gaps, openings and under the drywall.

I'll have to look into salvage yards around here - thanks again for the input.