Sleeper subfloor, what's your experience and should I do it - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 5 Old 11-15-2012, 08:37 PM - Thread Starter
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I am designing my new basement home theater and have been leaning towards using 2x4 sleeper construction with 3/4" OSB subfloor on top for my home theater and entire basement project.

The reason I am leaning this way is from having a previous home theater setup which had a simple floor of carpet with padding over top of the concrete directly. The issue with this setup was the complete lack of sound transmission through the floor. The bass impact from front speakers and subwoofer were completely missing at my seating position. When I later put the same setup on a first floor with traditional wood framing, I immediately noticed the sound transmission through the floor and made me feel more like I was in the movies and music, not just hearing them, but feeling them.

If I put in a sleeper floor, I will need to remove and rebuild my staircase to accomodate the extra 2 1/4" in floor height. I can only have a maximum variation in stair height between any two treads of 3/8" from what I have found. This is a larger under taking than I would hope, but fully within my capabilities and budget.

My question to the other home theater builders out there is if my last experience of a plain concrete floor was somehow incorrect and if people would recommend carpet over concrete? What has been peoples experience with and without sleeper construction and would the sleepers add other unforeseen problems such as resonances or other anomalies? I am also going to extremes to sound proof the theater room and wasn't sure if a sleeper subfloor that is not physically connected to adjoining rooms would help reduce sound transmission unlike the concrete floor which will join all rooms together regardless.

I have no height issues, 9 foot basement ceilings and only one soffit of 10" over the TV screen. I have no water or dampness issues and a cold floor is not my concern either. If I do a sleeper floor, I will put down plastic, then treated 2x4s flat, using a powder actuated nailer, attached to concrete and then screw the subfloor to those. I am on the fence about adhesive between 2x4s and subfloor if I even need to pull up the subfloor to run wires, fix water damage, etc. I also plan to build the walls directly on the concrete and then put the sleeper subfloor inside the rooms not quite touching the walls sealing the gap with accoustic sealant.

I currently have one JL Audio F113 and may get a second for the theater and have Thiel 2.3, 1.6, and MCS1 speakers.
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post #2 of 5 Old 11-15-2012, 10:09 PM
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Originally Posted by hoehne View Post

What has been peoples experience with and without sleeper construction and would the sleepers add other unforeseen problems such as resonances or other anomalies?
First, I have no experience with this, personally - so this response is pretty much academic - mostly in a Monday morning quarterback way.

I wouldn't be too concerned about resonances from the floor, though I couldn't say you won't have them - especially with only one layer of subfloor. I've read other opinions like your experience that mechanically coupling the sub(s) to the floor enhances the LFE experience. I understand that perspective, but I would encourage you to trust the mixers to have designed the track with the right amount of bass in it (and don't be afraid to run your sub hot if that's what you like - many do). If you're not feeling it, it's because of the way your system is working, IMO. The trouble and expense you'll go to to build the floor, ensure it doesn't resonate, and fix the stair issue would be better spent on more subs properly integrated. Chances are (from my reading here) that the issue you had was with unevenness in your bass response (in frequency and position), not with insufficient output or a lack of house-shaking.

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post #3 of 5 Old 11-17-2012, 01:39 PM - Thread Starter
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I picked up one of the Mike Holmes books last night to see what advice was in there on basement finishing.

After reading this, I am convinced I want a subfloor of some kind. The solution he posed in the book was to use the 1" thick rigid foam board (pink or blue stuff) directly on the concrete. Foam in around the perimeter and then lay 5/8" T&G OSB on top of that. Use Tapcons to attached the OSB to the concrete through the foam board. This will act as a moisture barrier and prevent any form of condensation of humid air on the cool concrete under the flooring.

This will add a 1-5/8" thickness to the floor. Given this smaller height, I feel having a staircase landing with a difference in step height between landing and floor and landing and next step of 1-5/8" or less to be manageable.

I was also using the rigid foam board to line my wall. Was planning on using 1" thick, Holmes says 2" thick. Need to reason this out a bit more.

Anyone else having experience with and without a subfloor in their theater?
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post #4 of 5 Old 11-18-2012, 04:47 AM
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I've never used the foam board, not that it isn't a good concept, but one thing to keep in mind is the regional differences and climate as it relates to building techniques. Mike works moslty north of the border. I don't recall him using foamboard for his project in California. My carpet and pad is directly on the concrete. Others In my area have been happy with the DriCore.

As this relates to the shake the whole house feeling you seek, Good subs and the addition of AuraPro sound transducers to your chairs will usually get the job done.
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post #5 of 5 Old 11-18-2012, 05:19 AM
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You'd likely be better off with a 3/8" layer of Acoustik Mat (rubber based product) with OSB on top of that (all installed AFTER drywall installation).

Subwoofers are designed to move air, not structures. Sure, you can get it to happen but if you want tactile sensations you're better off using "stuff" designed to do that. Sound transducers are at the bottom of the budget pole, D-Box is at the other extreme.

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