Help! Subwoofer causing granite to crack

deb_nick

Auditioning
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Nov 24, 2006
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Deb
My husband has set up his home theatre room in the basement. Directly above it, on the main floor, is the kitchen which has granite tiles on the floor. I noticed a hairline thin fracture going across the tiles from one side of the kitchen to the other side. And then I noticed a new fracture roughly parallel to the other fracture a few months later.

I'm wondering whether they're caused by my husband's 1000W subwoofer (although it's never turned up fully). Could the vibrations from the home theatre system be causing the kitchen floor above it to shift/shake slightly? And because the granite and the thin bed of concrete it's set in has no give, that could be causing the tiles to crack. Does this sound plausible? I can't think of any other reason for the cracks in the tile.

Other than turning down the subwoofer (which is our current solution), I'd like some ideas on how we can contain the sound in the home theatre so that it's not shaking the rest of the house. I'm looking for a DIY solution if possible. Much appreciated, thanks!
 

Eric_L

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Nov 2, 2002
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Eric
I seriously doubt that the sound from your sub is even remotely close to cracking granite - though that'd make a FANTASTIC sales pitch if it could be somehow proven!

Some things that'd be helpful to know; Is the sub on the floor or wall or ceiling? In what relation to the cracks above it? Where are the cracks in relation to the walls both on the same floor and basement - particularly load bearing walls. How long have you had the tiles? How old is the floor beneath them?

It is not uncommon for a floor to settle after reconstruction or remodel. If the tiles are adhered directly to the floor then that stress could easily crack them.
In Florida we do not have basements (3' water table) but tile floors are very common. SOme of the higher quality craftsmen will install tile over a sheet of felt to insulate it from settleing of the concrete foundation - especially in new construction homes. If I were going to bet on something I would bet on that before your sub.

As far as containing the sound - that's a bit trickier - particularly for the bass. High and mids are relatively easy to contain - sometimes just closing a door is enough. You can build a second ceiling and insulate it. Put in a heavier door. The bass however will travel. I recently heard the bass only from a concert at a stadium three miles from my home.
IMHO anything you do to reduce the sound of the bass will detract from the whole experience. I will suggest thought that 1000 watts may be a bit excessive for most basement sized theaters I've seen - how big is the speaker? How big is the room? (W/L/H) I have a 15" 700w Velodyne sub in my great room which is plenty - and that room is 35X20 with 14' vaulted ceilings with an open 8X8X6 cupola in the center. It may be that a smaller sub will still rock your world down there without intruding on the occupants in the rest of the house. But I wouldn't worry about the structural integrity of your house. Walking across your floor is far more stressful on it than the sub.
 

Bud Huey

Stunt Coordinator
Joined
Jan 11, 2006
Messages
73
I have never heard of a subwoofer cracking tile floors, but I agree with Eric - it would make a great sales pitch for a subwoofer manufacturer. Kind of like the old commercials where a guys glasses cracked when his buddy cranks up the stereo.

Anyway, my thought would be that the cracks in the tile floor are probably caused by settling in the house. Do you know if the tiles have 'wonderboard' underneath them or is there just a layer of mastic holding the tiles to a plywood subfloor? You should have the floors checked out by someone who knows about tile flooring.

Good Luck,
Bud
 

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