recommendation for turntable vibration damping

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.

Considering that the work you are doing will not be "load bearing" per se- I think ALL options (suggested thusfar) are OK.

True, a crawlspace is not as extreme an environment as the open air. Your jack will prob be fine.

I think you'll be very surprised at just how effective a mere fraction of what you are proposing will be. Hard to imagine- but bracing just two or three joists alone will be a huge inprovement. Now- factor in what you are contemplating and multiply it by 200%. Your floor won't move by any measurable degree. Audio speaking of course...