Wall construction question

I have a section of wall where the wall will run parallel to the joists above. Perpendicular to the joists (and wall) are a bunch of electrical and drain type pipes (about 3-4" down from the joists above and spanning a few feet). Is there a wall detail around for something like this? There is no room above the pipes for the 'double header' part of the wall. This is the HVAC side of a double wall to isolate the mechanicals from recording space.

A picture or several would help considerably. Andre

Here is the pic. The wall will begin attached to the left concrete foundation wall. The PVC pipe there is flush with the concrete. I assume I would run a treated 2x4 up the wall (like the bottome plate) and anchor that to the concrete up to 'just below' the PVC pipe. From there, I'm scratching my head. .

Thanks for the pic, it clears things up. Unfortunately you can not leave a gap and expect any significant sound isolation. My suggestion is to build the wall top plate right up to pipes cutting grooves in the drywall for the pipes, build the drywall right up to the ceiling and sealing the remaining spaces around the pipes with caulk. Good luck and keep asking questions if it isn't clear. Andre

Thanks for the response. I'm actually looking to find out how to attach the top plate to the joists above. I'll use the 'cut out' suggestion for the HVAC side drywall. The other side will be a second wall with a ceiling hung off Sound Clips with 2x5/8" drywall/green glue combo. That with the joists stuffed with insulation above the walls and around the pipes should give me decent isolation from the HVAC noise.

MMazurek wrote:

Thanks for the response. I'm actually looking to find out how to attach the top plate to the joists above. I'll use the 'cut out' suggestion for the HVAC side drywall. The other side will be a second wall with a ceiling hung off Sound Clips with 2x5/8" drywall/green glue combo. That with the joists stuffed with insulation above the walls and around the pipes should give me decent isolation from the HVAC noise.

Don't forget the requirement for fireblocking here. In the picture detailed here, you'd have to block up against the concrete below the piping and around where the 45 joint is. There are many pictures of fireblocking examples on the site. Rod's put up a bunch of these and I'd bet they are somewhere in the sticky lists. Basically - frame so your top plate is where you extend a thin plywood / 5/8 drywall / compressed rock wool sandwitched to brush up against the concrete and use fire rated caulking to bridge the slight gap where the rockwool touches. Consider your options for moving that pvc as well - what is it supporting? A basement pump system? Are you willing to do plumbing to re-route them for a more efficient frame & drywall detail for sound isolation? I did this in two spots for my basement build.

The wall I'm trying to figure out will start on the near side of the 'vertical' PVC pipes at the concrete wall on the left. It will span to the right. The 'far' side (where the ejector pump, shelving unit, HVAC stuff, etc. is) will not have a finished ceiling. It will be open (as it is now). Thanks for the help, Cram. I think it's AWESOME that you've included your reference links in you build thread. Searching can become quite cumbersome a task for some of the specifics. (And we all know, some of those specifics can really screw you in the end.)

MMazurek wrote:

Thanks for the help, Cram. I think it's AWESOME that you've included your reference links in you build thread. Searching can become quite cumbersome a task for some of the specifics. (And we all know, some of those specifics can really screw you in the end.)

Spread the love - do the same in your thread. Much of the forum outside of sticky's is disconnected and not linked logically. that was why I started that link section. Actually - throw this link up on your build thread. This periphrial info can help people coming in after you for sure.