recommendation for turntable vibration damping

Thanks again, all, for your replies.

Even though the TT is now on the wall, I realized that I should still support the floor from underneath.

I like the automotive scissor jack route, atop a concrete block (and potentially below a 2'x2" or 4'x4").

The area I'm trying to support is 13'W x 10'D, with joists running from front to back and spaced 16" apart.

I'm thinking that instead of just supporting the equipment/rack and area under the 2 speakers, maybe I should just brace the whole floor.

Any thoughts on how many jacks I should use in that space?

How much is enough to barely get by (I'm guessing area under the rack + 2 speakers)? How much is enough to "do it right"?

Also, if I go the 2'x2" (or 4'x4") route, would you recommend 2 (or 4) jacks supporting each board?

Thanks so much for your thoughts.

I told ya!

..wall mounted shelves are the way to go. I'm so glad you are reaping your just rewards. ;)

about the floor-

Block it first!! Whatever you choose to do for a pier, put a healthy amount of cross-blocking in between the joists first (say...every 2-3'. staggered) and I bet that makes a huge difference all by itself. Be sure to use the same dimensional lumber your joists are and be sure the wood is pressure treated.

I would do this: In an area where you have pre-selected to brace with a pier- drop a plumb line down into the soil and excavate a hole with a foxhole shovel that is below the frost line (whatever it is in your area) by at least a few inches and approx 2' by 2' square. Drop a large 18" by 18" patio stone of compressed concrete in the bottom of the hole and level it. Cut a piece of 6X6 PT lumber post that is exactly as long as the top of the stone to the top of your joist and then cut a notch in the post to accomodate your joist. Carefully tap the post in place and drill a 3/8" hole horizintally through the post and joist join and install a galvanized cairrage nut/bolt with fender washers. Double check for plumb and then tighten the nut. Back fill the hole and tamp it hard. 1 of these piers in the right location (after you have installed plenty of blocking) will make your floor rock solid. You can always add as many as you like- but 1 good one should be PLENTY for a room your size.

Thanks, Valve & Vinyl.

Dumb question: Does "blocking" refer to connecting joists with shorter pieces of wood (16" apart around here)?

The blocking could be hard to accomplish given that I just installed insulation between all joists.

I also may have screwed up because I didn't see your post before hitting the hardware store today.

I purchased a 4"x4"x8' and 2 adjustable floor joist jacks (the local hardware store only had 2) such that they are near the minimum of their range. I positioned the 4x4 so that it was perpendicular to the joists (it's supporting 6 joists). I used the jacks under the 4x4. I figured I would see how well it worked and then add more if necessary (I would need possibly 2 4x4x4' & 1 more 4x4x8' to cover it, given the pipe situation).

Does the method you suggested (hole + patio stone + pier) replace what I did above? It sounds like it does...and it sounds like a more elegant solution.

Should I not add the 2-3 additional 4x4's w/ jacks? The jacks (36") are like $30 a pop.

Thank you!!!

Hi,

Lumber isn't cheap either. I just put in a new deck 12' X 12' and even though that's pretty small- it set me back nearly $2K. Ouch.

Yep- blockling is putting in a piece between the joists (or studs).

The only problem I see with your joist jack method is that you are at the mercy of nature, in that you will probably need to re-adjust it often because of heave and expansion/contraction. A jack like that indoors remains fairly stable; When it's exposed to temperature outdoors....

When a builder puts in a bathtub, stairwell, or anything else that requires either a cut-out in the joists and/or extra bracing, the common method is to add blocking. It may not seem like it would add a significant measure of support but it certainly does. When the joists are allowed to flex independently of each other- they do. When held to the rigidity of its neighbors (other joists)- they don't. Pretty simple.

Use whatever type of column you wish, but I would still block the joists to the hilt. If you recently added insulation, you could just make a header or horizontal beam to distribute the load of your column of choice. This could serve to replace the blocking (sorta). Make sure you toenail the beam in an X wherever it meets a joist though. I'd double up (sister) a 2X6 (at least) for your header/beam. 2X8 would be better. I'd put two columns (per beam) if doing this method.

Thanks again, V&V.
I ake your point about the joist/jack method being subject to the mercy of nature. That said, the crawlspace should be a more constant temperature than a place that receives a mix of sun and shade.

I'd think that any solution in the crawlspace would be subject to the same mercy of nature -- even the pier solution you proposed -- althoguh perhaps to a lesser degree.

I will see how feasible blocking is for me, given the work I did on the insulation.

If I read your response correctly, you think the beam idea that I've tried with adjustable jacks (2/beam) as columns is OK. I know it does not fully replace the blocking, but it sounds like it is an improvement, albeit one that may need periodic adjustment.

I added one such header/horizontal beam, and based on the location of equipment in the room and the space/pipes below, I feel like I need to add at least two shorter beams. I could not emply one to span the width of the space due to crawlspace constraints.

Since the listening area is one section of a larger room, do you think it's wise/appropriate/or unnecessary to support the rest of the room (i.e., no equipment will be located in this area)? The listening area is already divided from the rest of the room by a header.

Thank you so much! I am learning quite a bit and feel like I'm almost all the way there in terms of making an informed decision about the solution.