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

Showing 2 responses by john_z

Hey all, thank you for some great feedback! I honestly did not intend this thread as a joke. What might seem obvious to someone with a background in construction or engineering is a fair question for someone like myself who works in an office cubicle all day.. I had no idea what a floating slab floor was or how they work to hold up a building, LOL!

Anyhow, my goal is to plan this project from the get-go and ask a few questions on this forum before construction to help me avoid costly mistakes and choose the best compromises in building out my new space. A few years back Russ Herschelman wrote a series of articles in Stereophile magazine which pointed out a whole bunch of mistakes in a home theater design that had been built in someone's basement and suggestions on how to fix them. He brought up several issues that many DIY people might not even consider that have a big impact on the final result. (I wish I could find those again!) The concrete floor is one of the "big questions" that I had about what to do, pros and cons, so thanks again for your feedback.

BTW, I live in the S.F. Bay Area, so the climate is fairly mild. The floor stays dry even during the rainy months, but it has some HUGE oil stains soaked into it that look very old so the garage has that faint repair-shop smell which I hope to get rid of. It's getting a new roof (badly needed) and upgraded electrical, too. Insulation and sheetrock (probably QuietRock?) for the walls and ceiling. I plan to include an air conditioner and heater to control the climate, possibly radiant heat in floor but still looking into cost/benefit. I like that radiant heat is silent but it would only be needed for a few weeks a year out here in sunny California.

Yes, there are three 2x4's that span across to reinforce the roof(?) I was wondering if they can be modified or removed to give me more headroom in there. The garage door is a wooden one-piece swing-up design which I plan to keep and frame a new wall behind it so the garage will still look the same from the outside - stealth. Oh boy, this is gonna be fun! -jz

Yes, I am planning on calling my local contractor, who did a very nice job remodeling our kitchen two years ago (I'm reminded of him every time the HELOC payment is due. LOL!) But I wanted some input from the "Gon before calling him for a bid. The more clearly I can define my wants, the better he'll be able to plan out an accurate bid and avoid "surprises" once building begins. I may have to show him some posts here regarding isolated ground electrical and other A/V-related stuff to avoid issues with the system. During our kitchen project, I caught him running Romex right next to my surround speaker wire/coax antenna drops that I had previously fished in-wall. It was easier for him and he did not realize it could cause hum or other problems in my A/V, (or didn't care).. Luckily I caught it and he was able to re-route the romex prior to the sheetrock going up. Regarding construction and safety, I'll definately use his guidance regarding our local codes and permitting that may be required..

I wanted to point out that I never meant this thread to veer into actual contruction issues, just which material sounded better/different given a choice. Lord knows I don't want to create an unsafe situation. But this is a rare case where I could take it either way, starting from a clean slate, as it were. If it were feasible to do a suspended floor on joists to really improve sound, (IF that's the case, not saying it is..) then I think it's a reasonable consideration. I'll be spending a lot of time in there once it's done! Besides,almost every home theater project you read about in the A/V magazines have some pretty big compromises due to pre-existing structure/layout/huge windows/you-name-it issues that they have to design around. Luckily, my garage has no windows, every dimension is non-divisible (which hopefully will tame most standing waves) and the only door will be a solid-core heavy duty outside type near the back corner with total isolation from other parts of the house. I think/hope this room's gonna ROCK!

Thank you all again for some great input and guidance. I'll try to create a "virtual system" post once I get started with some pics to show the progress. Regards, -jz