Insulation questions

[crokett]

The wall between my shop and the family room is being framed this week. Drywall will get hung next week. besides fibreglass insulation between studs, is there anything I can put under the sheetrock to help with attenuating the noise?

[LarryG]

The best way to inhibit the transfer of sounds and impacts is mass -- say a foot of masonry. Next best is two separate partitions -- two fully independent stud walls an inch or so apart. Then comes an unbalanced assembly, which is probably what you'll have to use.

On one side ONLY of the partition, apply a layer of 1/2" Homasote or equal and then apply the gypsum board over that. On the opposite side of the wall, apply resilient furring channels horizontally over the face of the studs at 16" OC, then apply a single layer of gypsum board. Or some combination thereof. Understand that you do NOT want the same layers on both sides of the wall. It is the unbalanced assembly, one side to the other, that does the most to kill the sound, by causing the two different sides to vibrate at different frequencies.

As the gypsum board is being hung, apply a continuous bead of acoustical sealant at the top and bottom. This is similar to weatherstripping around a door or a window -- even if the basic assembly is sound, the cracks and crevices will kill ya so you gotta seal up all the places sound waves can get through.

Do not locate electrical boxes on opposite sides of the wall within the same stud space; instead, stagger them by at least one stud space. Seal around the boxes with the acoustical sealant before the electrician installs the devices and covers.

Use sound attenuating batts, not ordinary thermal batts. Don't let the contractor try to tell you there's no difference.

As with inhibiting heat loss, it's the detail work that makes most of the difference. But don't expect a miracle. There's only so much you can do with this kind of light construction.

[dlminehart]

Wow, thanks for the detailed info, Larry!

[onedash]

Have you looked into blown in sound insulation? If I remember right its like recycled denim or something. I don't know if its better than spray in foam or what the price difference is.

[drumpriest]

Here's a tip from the music industry. A double framed wall transmits far less noise because the surface being vibrated on one side is not in direct contact with the other wall. Basically make the wall double wide with a small gap between.

When we framed up my dad's new house, we used 2x4 for the outside wall and 2x3 inside.

[crokett]

Larry,

Thanks for the info. I talked about it to my brother (the contractor). I will look at how much the Homasote costs - I can always put it on the shop side. That side will be studs for short term. He also pointed out that I usually pull my big noisy tools outside anyway, both for noise and mess.

[mleichtle]

To add to drumpriests post, another way is use 2x6 (or 2x8) plates and stager the studs at 12" o.c. then batt isulation is woven through the wall. Same concept, but a 6-1/2" thick wall is a stanard size for a door.

[Tom Miller]

quote:Originally posted by mleichtle

To add to drumpriests post, another way is use 2x6 (or 2x8) plates and stager the studs at 12" o.c. then batt isulation is woven through the wall.

Now that's a good one (and definitely new to me)! You get a lot of the benefit of a double wall (i.e. decoupled transmission from one side to the other through the studs) without the hassle and wasted space of a double wall.

Regards,
Tom

[onedash]

Isnt Homasote recylced newspaper??? Wouldn't that be more flamable?
I always thought attached garages had to have a fire barrier between the living space and garage and a fire rated door. The house im renting has wood paneling in the garage. I don't even know if there is any insulation in there. This is definately a fixer upper but im guessing it would sell at normal market value. I just don't see how housing is so expensive. I think it has a lot to do with collecting more taxes. But thats off topic. That staggered studs sound like it would be good. Anyone ever use spray foam? It seems like the general rule is double the price or fiberglass. Does a small job like one wall increase the price ratio???

[crokett]

I checked on the homasote. The supplier in my area lists it for 25 bucks a sheet. Not sure that is in my price range. What if I put some sort of rubber mebrane on the studs behind the sheetrock?

[dlminehart]

Since you've yet to frame the wall, I think Leichtle's idea is your best bet. Minimal additional cost for a few more studs and wider sill plate, plus a little extra insulation since it undulates.

[JTimmons]

I was watching HGTV and they came out with a new type of sheetrock that has what appeared to be sheet metal sandwitched between to pieces of sheetrock. It was supposed to be designed to eliminate traffic noise on homes or dwellings close to highways and busy streets. Not sure about the cost or name of it though, it's been awhile.

[Thalermade]

I used a product similar to the one on the link below, with mixed results.


http://www.gp.com/build/product.aspx...1&hierarchy=pc

Your door will be a weak link. Also keep in mind your door frames will be wider than "normal" whether you use the offset stud design (which I should have also done), or adding some type of sound deadening boards.



Have fun,

Russ

[LarryG]

The Homasote is flammable but so are the wood studs. It's the layer of gypsum board over both that provides the fire protection. Still, if the idea of Homasote makes anyone antsy, omit it and use two layers of gypsum board on that side of the wall instead.

Staggered studs are another good option that I forgot to mention. Not quite as good as two completely separate walls since the studs are attached to the same plates, but better than a single row of studs if the additional space required is not a problem. However, you should still use a different makeup of materials on the two rows of studs, so that they will vibrate at different frequencies.

The resilient channels are a HUGE help, too, since they really help isolate the vibrating plane of the gypsum board from the studs.

EDIT: Just read down the thread again, and want to emphasize the above. If you build two separate stud walls, or stagger the studs and weave in the insulation, and then apply a single layer of gypsum board to both sides, without doing anything to unbalance the assembly, you are largely wasting your time and money. You MUST get a different massing of materials on the two sides of the wall to do much good.

[ejs1097]

Great thread. I'm going to be WFH soon in the basement and will have to try to lesson the noise from the furnace. Thanks Larry.