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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
nsgarch's avatar
nsgarch
2,524 posts
 
John, you can move the cross ties closer to the peak (a lay term for ridge) so you get better headroom (they're there to keep the walls from splaying outward under the weight of the roof ;-) Make sure you do it to every pair of rafters to be safe. Placing 18" diagonal knee braces nailed near the bottom of each rafter and the top of the corresponding wall stud (put an xtra stud in if there's not one near the rafter) will keep the building from racking. You should also put in diagonal metal bracing (two metal straps nailed across the wall studs in a big "X" on each sidewall of the garage) to insure earthquake resistance.

Removing the existing slab is an unnecessary expense, if you don't have moisture problems. A level sand bed over an electric radiant heating pad with sand set pavers on top would make an easy and attractive floor.
zieman
339 posts
 
John, If you would like to become intimately familiar with the term "Red Tag" and your city's Building Dept., follow Gumps advice. Roof trusses are an engineered product, leave them as they are. Since I am also in the SF Bay Area, please call me over when the plumbers tape diagonal bracing is looked at. The City may take photos for their "wall of shame". My definition of an "unnecessary expense" would be The City's requirement that you demo this now non-complying structure and rebuild to current code from approved drawings. Figure about 85 bucks a foot by following Gump off the cliff. My suggestion might burn up 2500 and add twice that in equity. Tough choice... Z.
c019740
30 posts
 
You might be better off demolishing the garage and start from scratch.
jaffeassc
166 posts
 
As a construction professional and an amateur audiophile my advice would be to tread very lightly with the advice regarding concrete repairs on Audiogon.
zieman
339 posts
 
Jaffe, I could not agree more. Good thing we are only getting incorrect input for a 200sq.ft. detatched structure! I am afraid I have to add that most of the audio advice is in the same league. Wasn't always this way here... "Those who can, do, those who can't, teach", fits these forum sitters. All one has to do, however is look at the profile and see if the advisor is a member with all the answers and no questions, as well as the extent of trading feedback. Thanks for the help! Z.
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