concrete slab vs/ wood floor - pros and cons


Audiogoners, given the choice, with sound quality being a top priority, which choice is usually better?

I have been given the green light from my wife, bless her heart, to convert our stand-alone 1935-era garage into a dedicated music/theater room - woo hoo!! The fact that it's a separate structure will be ideal for playing loud movies whenever without bothering anyone in the house. The space is roughly 11.5 x 17' and I think it will make a terrific intimate theater. It's completely unfinished inside and has a sturdy stucco exterior. It's a very solid structure. However, the concrete floor has some large cracks lengthwise due to settling so it is pretty crowned in the middle. If I keep the concrete, I will need to build a floor over the slab and shim it quite a bit to level it out enough to install the underlayment. Headroom is limited as the walls are just over 7 feet, although the roofline peaks at just over 10' in the center, enough height to hang my projector.

If I removed the concrete, then I could dig down and build a normal floor over wood joists with a nice hollow space underneath. My house is built over a crawlspace with hardwood floors and I like the quality of bass and overall sound I get in our living room. The downside is that it would be more difficult to convert the garage back later to use for parking a car if we move. I was thinking it might be cool to design this type of floor and then have space below for insulation, wiring, etc. without sacrificing any height. Maybe the floor could even be designed as a sort of bass trap to help with the sound. Any thoughts? -thanks, -jz


john_z
After 60 years, the slab ain't goin' anywhere, but it most certainly wasn't waterproofed underneath (not in those days.) So what you want to do is cover the existing slab w/ construction grade polyethelyne sheet, the a layer of 2x2 or chicken wire mesh propped up on 4x4 squares if 3/4" thk plywood or fir, then call the concrete truck and tell them you need 2,5 yards of lightweight concrete topping layer (2" over the highest existing spot) and to notify you when they have extra from a job they're finishing. If you and the garage are ready when they call, you'll make out like a bandit because they hate having to dump that stuff!
Is this a joke? If not this is really a no brainer. In other words you would have to have no brain to consider digging up a slab, putting in joists etc. because you like the sound you get in your living room! Get real!
I don't see why you could not easily (especially with such a small room) simply go to the local hardware pickup a couple gallons of pre mixed concrete, take a big spackle type scrapper, pour some into your cracks smooth over, let it dry, simply go and get a really good (vapor barrier) type plastic foam that is used for underlayment for like the Cheap pergo flooring, than drop a thick carpet pad over that, and then carpet with a basic medium pile cheap carpet? I mean we are not really talking a very difficult thing here especially for the age of the building.

However not sure if you have any seeping or whatever under the garage walls that you will not end up with a soaked carpet acting as a sponge from the outer edges of your foundation.. In any case it would probably not cost much more than a few hundred bucks to do what I just listed..
Oh and yes it will sound Pretty Good!

I would put up some cheap absorbtion and diffusion products on the walls as well, it sounds like you might not even have drywall up yet, or if you do thats fine and just treat with some good bass traps or other foam products for studios possibly..

Other thing to remember is the garaged door, if its metal it will have some sound echo probably.

Are you putting in a Heating / cooling unit? If your gonna put any good gear out there, and furniture for that matter I would have a decent environmental control over the weather.. A projector, DVD player, whatever else will probably not like any extreme temps. Hot or cold.

If the floor is really un-level It will not cause you any sonic issues, however might not be good if it traps moisture or something.
The older concrete gets, the harder it gets -- and I mean jackhammer hard!! You have two problems: levelling, and (potential) moisture. So far, you haven't said if your garage floor ever gets damp or even floods. So is moisture a problem or not? If not (the garage is on high ground?) then you could just level the floor with a fine sand bed and sand-set pavers (brick, stone, terrazo, slate) to make a very beautiful floor, with a really nice oriental rug on top. And if it's cold where you live (where was that?) you could lay some radiant heating elements in the sand bed. The 7' wall height shouldn't be a problem if the roof ridge is at 10', but there are probably cross members at 7'. There is a solution for this too: knee braces at the walls and cross braces near the peak.
Home depot sells a sub floor board which is easy to install. It comes in 2'x2'sheets and could be leveled out for any irregularities in the floor it will give you a nice warm floor and it helps out with acoustics you can put any kind of flooring over it you want rug wood or easy to install laminate. it adds approximately, a inch to hight even after you add flooring this is the ideal thing to do for leveling comfort and acoustics.I have a article on acoustic property's if I can find it.each Pallet covers 70sq foot you wood need approximately, 3 link http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?jspStoreDir=hdus&catalogId=10053&productId=100388255&navFlow=3&keyword=sub+floor&langId=-1&searchRedirect=sub+floor&storeId=10051&endecaDataBean=com.homedepot.sa.el.wc.catalog.beans.EndecaDataBean%4059912410&ddkey=Search OVRX 35 Pk. 2 Ft x 2 Ft Sanded OSB Insulated Sub Flooring Tile

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