Riser/Platform floor material - AVS Forum
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post #1 of 16 Old 07-09-2014, 01:21 PM - Thread Starter
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Riser/Platform floor material

What's best to use for a riser, or platform, floor?
I've read MDF and plywood. MDF is supposedly more sound dampening. What about hardwood sheets?
I've also read at least 2 layers of 3/4 in.

Thanks
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post #2 of 16 Old 07-09-2014, 03:09 PM
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Buy proper subfloor - tongue and groove. It's more expensive, but the T&G helps keep down the squeaks. Two layers is good. There should be something between them as well - roofing felt is supposed to be good - to keep down the squeaks. Green Glue is a good addition in place of roofing felt, if you have it. When you screw the sheets down, use screws long enough to screw the top layer(s) all the way down into the joists.


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post #3 of 16 Old 07-09-2014, 03:25 PM - Thread Starter
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Quote:
Originally Posted by HopefulFred View Post
Buy proper subfloor - tongue and groove. It's more expensive, but the T&G helps keep down the squeaks. Two layers is good. There should be something between them as well - roofing felt is supposed to be good - to keep down the squeaks. Green Glue is a good addition in place of roofing felt, if you have it. When you screw the sheets down, use screws long enough to screw the top layer(s) all the way down into the joists.
Plastic moisture barrier under the riser? My floor is concrete as it's in the basement and the carpet hasn't been installed yet.

Thanks again. Great info, I'll get the T&G and roofing felt.
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post #4 of 16 Old 07-09-2014, 05:01 PM
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I like three layers of 5/8 OSB with green glue between layers. I haven't ever had one squeak even without the T&G.


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post #5 of 16 Old 07-09-2014, 06:12 PM - Thread Starter
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Here's some 3/4 osb t/g. Looks like this could be a good floor.

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post #6 of 16 Old 07-09-2014, 06:24 PM
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That's what I'm using. In fact, if you could swing by with a truck, I need about three more sheets. But if BIG says you can skip the tongue and groove, he's probably right- but note he is using GG. (I am as well) In the places where I have butt seams in my floor, I try to leave a small gap between the sheets and use a closer screw spacing - but that may not be helping (not hurting).


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post #7 of 16 Old 07-09-2014, 07:50 PM - Thread Starter
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Quote:
Originally Posted by HopefulFred View Post
That's what I'm using. In fact, if you could swing by with a truck, I need about three more sheets. But if BIG says you can skip the tongue and groove, he's probably right- but note he is using GG. (I am as well) In the places where I have butt seams in my floor, I try to leave a small gap between the sheets and use a closer screw spacing - but that may not be helping (not hurting).
My delivery charge to Atlanta would be a bit high.
No GG for me unfortunately. I will likely use liquid nails in addition to screws. I did get #30 roofing felt which I'll use between the flooring.

Did you use a moisture barrier on the ground?
Why'd you go with 8" joists as opposed to 12" which you used for your frame?
It looks like you didn't put any insulation between your joists. Is that the case, and if so why not?

Last edited by jszei; 07-09-2014 at 08:05 PM.
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post #8 of 16 Old 07-09-2014, 08:12 PM
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I use the same roofing felt that is often used between layers as the barrier between concrete floors and riser framing.


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post #9 of 16 Old 07-09-2014, 08:16 PM
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I did not use anything under the riser - maybe one day I'll regret that, but I doubt it. The riser is resting on finished hardwood flooring. In places that framing rests on concrete, I used pressure treated lumber.

The 8" joists in the riser are: cheaper; easier to handle; will never touch the ground, so they won't cause the riser to rock or be uneven; and allow the air cavity of the riser to be a single continuous space, should I decide to try to use it for bass trapping. The outermost two joist bays on each side of my riser were sealed with some OSB and 6mil plastic and filled with sand, because I'm putting subwoofers on them. The middle joist bays were left mostly open, but I did suspend r-13 insulation on hangers in them before I topped them with subfloor.
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post #10 of 16 Old 07-10-2014, 12:57 PM - Thread Starter
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Quote:
Originally Posted by BIGmouthinDC View Post
I use the same roofing felt that is often used between layers as the barrier between concrete floors and riser framing.
Have you ever used a plastic barrier? The only thing that concerns me about plastic on concrete is moisture developing on one side or the other and creating mold since it gets trapped. I feel a little safer with the felt.
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post #11 of 16 Old 07-25-2014, 02:47 AM
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Quote:
Originally Posted by BIGmouthinDC View Post
I like three layers of 5/8 OSB with green glue between layers. I haven't ever had one squeak even without the T&G.
In some threads I see risers with suspended joists suggested as a way to gain some tactile bass response on a concrete slab.

It also seems that the best practice is as you described
What is the purpose of such a stiff, heavy and damped sub-floor?
Reduce tactile response?
Lower the resonant frequency?
Prevent the riser from acting like a drum?

If the answer is yes to the first one then how do you get some shake on concrete without going to absolute sub-woofer extremes or installing tactile transducers, which seem to have a "gimmicky" reputation for the most part?

.

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post #12 of 16 Old 07-25-2014, 06:21 AM
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Quote:
Originally Posted by jszei View Post
Have you ever used a plastic barrier? The only thing that concerns me about plastic on concrete is moisture developing on one side or the other and creating mold since it gets trapped. I feel a little safer with the felt.
totally off topic - just out of curiosity what region of chicago are you building in?


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post #13 of 16 Old 07-25-2014, 07:23 AM - Thread Starter
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totally off topic - just out of curiosity what region of chicago are you building in?
I'm in Naperville.

I ended up using #30 roofing felt between the concrete and the joists. Given the lack of information available on a plastic moisture barrier, and the common use of felt I went the safer route. First picture is of the felt and some of the insulation. Second picture is of the finished riser. I decided to only make it large enough to hold one row of seats as I don't have the ceiling height to add a third row. The room is 35 feet long and the back area will have a desk and some cabinetry.
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post #14 of 16 Old 07-25-2014, 04:20 PM
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I just used 3/4 inch ply wood and screwed it down. Haven't had a single problem. Filled it in with a Roxul Safe N Sound in back and basic pink insulation in front. There are picks in my link.

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post #15 of 16 Old 07-27-2014, 12:10 AM
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Was hoping to get an answer for this.
Jeff?

Quote:
Originally Posted by BIGmouthinDC View Post
I like three layers of 5/8 OSB with green glue between layers. I haven't ever had one squeak even without the T&G.
Quote:
Originally Posted by DavidK442 View Post
In some threads I see risers with suspended joists suggested as a way to gain some tactile bass response on a concrete slab.

It also seems that the best practice is as you described
What is the purpose of such a stiff, heavy and damped sub-floor?
Reduce tactile response?
Lower the resonant frequency?
Prevent the riser from acting like a drum?

If the answer is yes to the first one then how do you get some shake on concrete without going to absolute sub-woofer extremes or installing tactile transducers, which seem to have a "gimmicky" reputation for the most part?

.
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post #16 of 16 Old 07-27-2014, 03:22 AM
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keep it quiet


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