I need to construct a riser for the backrow. It will be 5' x 6'. What is needed to insulate it so it doesn't sound so hollow when people step on it? What do I ask for at Home Depot?

Fiberglass insulation - r13 or r19.

Double layer of decking will also help keep it quiet.

Big - quiet from what? Footfalls on the riser? I put double layers on the riser because I thought it was to dampen "people" noise from the top. But I was never really sure why it needed double layers.

Footfalls on the riser

correct

Unless you are going to put hardwood or tile on it, I don't see the need for double layers of decking. What other part of the house do you have a double subfloor? Also, do you routinely have people milling about on your riser in the theater when you are watching movies? I don't seem to have that issue.

I would recommend filling the cavity with insulation to stop any resonance. Do that and add 1 layer of 3/4" OSB and you're good to go.

What other part of the house do you have a double subfloor?

Actually I've been in a number of homes under construction that used double layer floors and even homes where they poured an 1 1/2 inch of concrete over a plywood sub-floor in all the rooms and hallways.

When I was building my riser I put a single layer on and walked on it and listened, then added another layer of plywood and walked on it before screwing down, it was a no brainer the double layer reduced the footfall noise.

Unless you are going to put hardwood or tile on it, I don't see the need for double layers of decking. What other part of the house do you have a double subfloor? Also, do you routinely have people milling about on your riser in the theater when you are watching movies? I don't seem to have that issue.

I would recommend filling the cavity with insulation to stop any resonance. Do that and add 1 layer of 3/4" OSB and you're good to go.

Why would you even want to do that unless you want to waste money? The riser I assume will be padded and carpeted. Isn't that enough?

Actually I've been in a number of homes under construction that used double layer floors and even homes where they poured an 1 1/2 inch of concrete over a plywood sub-floor in all the rooms and hallways.

The double plywood and/or cement is for a solid backing for ceramic tile.

The double plywood and/or cement is for a solid backing for ceramic tile.

I asked at the time and that was not the case. They were going to use carpet.

actually it was probably a poured gypsum concrete floor:


From USG
Gypsum concrete underlayments offer a wide range of performance features and
application benefits. They accept virtually any type of floor covering, including vinyl
composition tile, ceramic tile, wood laminate, glued-down hardwood and carpeting.
Because they can be applied thinner than portland cement products, gypsum
concrete underlayments are lightweight, making them ideal for wood-framed
buildings where concrete-based alternatives may require structural alterations.
A 3/4-inch-thick gypsum concrete underlayment floor weighs approximately 6.25
to 7.5 pounds per square foot and has a dry density of only about 115 to 125
pounds per cubic foot.
Gypsum concrete underlayment assemblies offer UL-certified fire ratings of up to
two hours. The floor’s fire resistance is due to the fact that gypsum is naturally fire
resistant. When exposed to flame, it releases moisture in the form of steam, thereby
slowing heat transmission.
Sound control is another key benefit of these flooring systems. The excellent
acoustical properties of a poured gypsum floor result from the product’s mass,
combined with the fact that the underlayment does not shrink as it sets. Unlike
portland cement products, which shrink, gypsum concrete underlayments seek
and fill cracks and joints, a major source of sound leakage between floors.
Gypsum concrete underlayment floor assemblies deliver STC (Sound
Transmission Class) ratings in the high 60s and IIC (Impact Insulation Class) ratings
of 55 and higher, even with hard-surface floor coverings.Gypsum concrete underlayments also install quickly and cost-effectively. The
product consists of a formulated gypsum cement mixed with sand and water. The
resulting slurry is pumped and poured in place, then “screeded” to a smooth,
monolithic surface. Depending on the floor layout, up to 30,000 sq. ft. of gypsum
concrete underlayment (3/4 inch thick) can be applied in a single day.

I asked at the time and that was not the case. They were going to use carpet.

That is the exception and not the rule.

Was this a custom home or a tract home?

I suspect that the two layer "rule of thumb" has a lot to do with the fact that we often over-build our rooms: two layers of 5/8" drywall, GG, special clips, backer-boxes, putty pads, 50 yr caulk, etc. We so get into the mindset of over engineering everything, that adding a second layer on the stage or riser just doesn't seem out of place.

I happen to have all of the OSB (and will likely have extra) to do a couple of layers, so I do plan on using it.

That is the exception and not the rule.

Was this a custom home or a tract home?

They were late 70's "custom spec" $2 mil homes in So Cal.

Quote:
Originally Posted by guamguam View Post
Unless you are going to put hardwood or tile on it, I don't see the need for double layers of decking. What other part of the house do you have a double subfloor? Also, do you routinely have people milling about on your riser in the theater when you are watching movies? I don't seem to have that issue.

I would recommend filling the cavity with insulation to stop any resonance. Do that and add 1 layer of 3/4" OSB and you're good to go.

Why would you even want to do that unless you want to waste money? The riser I assume will be padded and carpeted. Isn't that enough?

No.

You add insulation to avoid it resonating like a drum. Take a set of bongos, put carpet on top, it will still work like a drum. Put insulation inside, and it won't. Insulation is cheap, anyways.

I only put a single layer of 3/4" plywood on my riser, though i did fill it with R-19. I also padded and carpeted it.The cost of the insulation was fairly negligible and my riser feels rock solid (no movement or hollow sounds, even when jumping up and down on it).

Can you build a single layer carpeted riser filled with insulation and be totally happy? YES .

You also don't need to put sand in a stage,
Paint the ceiling black,
Acoustically treat the walls,
Add bass traps,
automate the lighting,
get a universal remote,
use an automated speaker equalization unit,
get powered reclining seats
add butt-kickers
zone the HVAC
get an air tight door

and the list goes on and on. They are all symptoms of the same disease.

Can you build a single layer carpeted riser filled with insulation and be totally happy? YES .

You also don't need to put sand in a stage, (CHECK!)
Paint the ceiling black, (CHECK!)
Acoustically treat the walls, (CHECK... though minimal)
Add bass traps, Eventually....
automate the lighting, (CHECK!)
get a universal remote, (CHECK!)
use an automated speaker equalization unit, Probably won't
get powered reclining seats (CHECK!)
add butt-kickers (CHECK!)
zone the HVAC (CHECK!)
get an air tight door Probably won't, though I did an exterior grade door into the utility room!

and the list goes on and on. They are all symptoms of the same disease.

Comments above... I currently rate an 8/11 on the HT sickness scale... with plans to deteriorate to a 9/11. :D

I hit 10 of 11. Just not doing the butt-kickers although I did future proof in case I wanted to.

No.

You add insulation to avoid it resonating like a drum. Take a set of bongos, put carpet on top, it will still work like a drum. Put insulation inside, and it won't. Insulation is cheap, anyways.

The riser will not resonate like a drum either way. Adding insulation in a riser is a step that is not needed.

Can you build a single layer carpeted riser filled with insulation and be totally happy? YES .

You also don't need to put sand in a stage,
Paint the ceiling black,
Acoustically treat the walls,
Add bass traps,
automate the lighting,
get a universal remote,
use an automated speaker equalization unit,
get powered reclining seats
add butt-kickers
zone the HVAC
get an air tight door

and the list goes on and on. They are all symptoms of the same disease.

What in the world is the sand for?

Risers are spec'ed at double layer on the top (often 3 layers) , screwed down, with roofing felt between the layers (to prevent wood on wood squeaks). First layer goes down with a bead of construction adhesive on the joists (which are usually spec'ed at 12" centers...). The goal is to build a squeak free, solid platform that won't act like a drum. Mulitple layers of deck also make for a nice larger diameter roundover for carpeting (and also likely provide enough thickness to staples won't come through the top).

You also might want to make sure the insulation is formaldehyde free.

Steeler, the cavity is fully filled with insulation to ensure it won't resonant. Further, all the insulation is often used to help deal with bass response issues (assuming the riser is full width and backs onto the back wall of the theater).

and we are talking about a small riser here.... Adding a second layer of decking could be as cheap as $10.

Risers are spec'ed at double layer on the top (and often 3 layers), with roofing felt between the layers (to prevent wood on wood squeaks). First layer goes down with a bead of construction adhesive on the joists (which are usually spec'ed at 12" centers...). The goal is to build a squeak free, solid platform that won't act like a drum. Mulitple layers of deck also make for a nice larger diameter roundover for carpeting.

You also might want to make sure the insulation is formaldehyde free.

Steeler, the cavity is fully filled with insulation to ensure it won't resonant. Further, all the insulation is often used to help deal with bass response issues (assuming the riser is full width and backs onto the back wall of the theater).


Use screws and PL 200 or liquid nails....no squeaks!

Maybe I'm missing something here. I am assuming this riser is going to be built over a concrete floor....right?

Then topped with padding and carpet. Then a heavy couch or recliners on top of that and what ever else you want to place on the riser. It's NOT going to resonate!!!! The ONLY way I see that insulation would be needed is if one places a down firing sub on the riser.

Risers are spec'ed at double layer on the top (often 3 layers) , screwed down, with roofing felt between the layers (to prevent wood on wood squeaks). First layer goes down with a bead of construction adhesive on the joists (which are usually spec'ed at 12" centers...). The goal is to build a squeak free, solid platform that won't act like a drum. Mulitple layers of deck also make for a nice larger diameter roundover for carpeting (and also likely provide enough thickness to staples won't come through the top).

You also might want to make sure the insulation is formaldehyde free.

Steeler, the cavity is fully filled with insulation to ensure it won't resonant. Further, all the insulation is often used to help deal with bass response issues (assuming the riser is full width and backs onto the back wall of the theater).

If you want a "nice larger diameter roundover for carpeting" all you have to do is overhang the 1 piece of sheeting and screw a piece of 2x2 or whatever dimension lumber to the front of the riser flush with the top sheeting. That way you don’t WASTE material!

The riser will not resonate like a drum either way. Adding insulation in a riser is a step that is not needed.

Do as you wish - but the advice here says otherwise. Its possible that the frequencies involved to trigger it might not be an issue based on the composition and dimensions of the riser, but why chance it over minimal $$.

For example, a basis discussion of sound isolation techniques (for walls) lays out the physics:

2. Absorption

Air cavities will resonate. Ever "heard the ocean" in a seashell? Ever blow across the top of a bottle and heard the sound? Both sounds are actually the trapped air resonating. A hollow wall will also trap air that will resonate. When the wall is vibrated by sound (from your neighbor), the air in the wall cavity is also vibrated, just like a drum. This air cavity is another means for sound vibration to travel from one side of the wall to the other.
http://www.soundproofingcompany.com/index.php?/library/articles/elements_of_room_construction

And antecdotally, a quick search of turned up a user with problems:

Instead of the solid 2x10's, you could use fabricated joist to cut some of the weight. I wouldn't use anything less that 3/4 ply, which in my opinion is still not thick enough for the deck. My risers didn't stop sounding like a drum until I added the third layer of plywood (3/4" - 1/2" - 3/4").

You also don't need to put sand in a stage,
Paint the ceiling black,
Acoustically treat the walls,
Add bass traps,
automate the lighting,
get a universal remote,
use an automated speaker equalization unit,
get powered reclining seats
add butt-kickers
zone the HVAC
get an air tight door


Wow I didn't realize I would start such an argument, but I did want to see if I could get Big riled up :)

I agree with Big that people like to over-engineer things to make their rooms perfect. I was just merely pointing out that I believe that a double layer on the riser provides no added benefit. I would say that everything else on his list has an actual discernible benefit. I don't personally believe that you can tell the difference between two layers and one layer on top of a riser.

"Maybe I'm missing something here. I am assuming this riser is going to be built over a concrete floor....right?"

Usually over a concrete or a wood floor (or occasionally a wood floor with a layer of Acousimat beneath it).

"Then topped with padding and carpet. Then a heavy couch or recliners on top of that and what ever else you want to place on the riser. It's NOT going to resonate!!!! The ONLY way I see that insulation would be needed is if one places a down firing sub on the riser."

In that case, optimal practises would mean a sand filled cavity under the subwoofer, down firing or not. Along with insulation elsewhere in the riser. :D One might even make a good case that you are missing a chance at having an inexpensive bass absorber that consumes no additional space in your room. And that would be wasteful.

"If you want a "nice larger diameter roundover for carpeting" all you have to do is overhang the 1 piece of sheeting and screw a piece of 2x2 or whatever dimension lumber to the front of the riser flush with the top sheeting. That way you don’t WASTE material!"

Edging out with 2x2" might shave a few bucks but then I loose stiffness and just maybe one needs an extra .75" or 1.5" inches of riser height, for proper sightlines. If budget is tight, why not use a sheet of OSB for the first layer?

Mine was easy...simple and cheap. Works like a champ. I went to Walmart and bought about 42 of those cheap pillows that cost about $3 each and loaded up the inside of my riser. You can see pics link in my signature of howI did it. One layer of plywood on top too.

I did not go the insulation route because I have small children and did not want to have to breathe those particles in and handle it. My pillows took about 10 min to put in...lol.

Looks like you've got close to 40 pillows (oops I see you posted the actual # at 42) so at $3 a pop that was some pretty pricey stuffing compared with insulation. Not that I don't like your idea. Just more expensive than the traditional insulation route. And if you get the paper faced insulation, it's easier to handle than the raw insulation.

Looks like you've got close to 40 pillows (oops I see you posted the actual # at 42) so at $3 a pop that was some pretty pricey stuffing compared with insulation. Not that I don't like your idea. Just more expensive than the traditional insulation route. And if you get the paper faced insulation, it's easier to handle than the raw insulation.


I used the fiberglass insulation with plastic vapor barrier... so even easier and cleaner to handle. :)


http://www.jmhomeowner.com/products/product.asp?category=FiberGlass&Product=ComfortTherm

I think one 87 sq/ft bundle cost about $40 and it did my whole riser with enough extra to fill the bays in my stage that i didn't fill with sand.

I will concur that the double layer dampens the footfall much more than a single layer. I have a double layer on *most* of the riser. But because of how the heights worked out (I know, I should have planned better) a small portion of my riser is only single layer. I definitely hear a difference between the two. Ironically, the single "problem" layer is the section that gets walked on when you enter the room. The double layer is the riser where the back row sits. So, yes, the double layer is definitely a benefit for foot traffic.

I was curious about the double layer have any other benefits, because I am currently debating whether or not to use it on the stage. I figured the stage will not get any traffic, so I need not worry about impact noise from footfalls. The speakers/subs will not be placed on the stage, so I need not worry about vibrations from them. I basically have an aesthetic stage, that will never be walked on. So I am single layering it.

When this topic came up, I was immediately interested in what the double layer was actually for. The stage is filled with insulation (third floor - no sand). But it was an opportunity to learn about the double layer after is came up. I feel as though I aggravated this debate because of my question about the footfalls ...

You guys have convinced me. I'm going to rip up my non insulated one sheet topped riser and fill it with vanilla pudding....no check that chocolate pudding it's a better insulator!:rolleyes:

The double plywood and/or cement is for a solid backing for ceramic tile.

I'm building a house right now and we're using concrete (both gyp-crete/lightweight and full weight) throughout the main level... nothing to do with tile.

On the riser I'm including in our future theater, though, I do think making it more solid will help with resonances and just a general feeling of being 'solid.' Concrete might be overkill there, but certainly an extra layer of something will be good, plus some insulation filler.

But, as many have said, this type of detail seems to fall in the category of "different strokes for different folks" when it comes to any "right" way of doing things.

I'm building a house right now and we're using concrete (both gyp-crete/lightweight and full weight) throughout the main level... nothing to do with tile.On the riser I'm including in our future theater, though, I do think making it more solid will help with resonances and just a general feeling of being 'solid.' Concrete might be overkill there, but certainly an extra layer of something will be good, plus some insulation filler.

But, as many have said, this type of detail seems to fall in the category of "different strokes for different folks" when it comes to any "right" way of doing things.

99% of the time when double plywood and cement are seen in a house it is prep work for tile the other 1% is for personal spec.

Who ya callin a 1%er?

You guys have convinced me. I'm going to rip up my non insulated one sheet topped riser and fill it with vanilla pudding....no check that chocolate pudding it's a better insulator

Should go perfect with the use of Peanut butter in the walls.

http://www.avsforum.com/avs-vb/showthread.php?t=785359&highlight=peanut+butter