John Sayers' Recording Studio Design Forum

need help with flanking problem via sprinkler pipe
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Author:  yosh [ Tue Aug 04, 2009 3:16 am ]
Post subject:  need help with flanking problem via sprinkler pipe


I'm leasing a space which is the second and only other unit in a building used as a wood stripping facility. The space is about 1000 square feet with a small front lounge when you first walk in the door and a small iso room at the rear of the space. Ceilings are about 12 feet high. The space is in Portland Oregon, USA.

I have done some construction to gain sound isolation. I have built a new wood stud wall between the two spaces with two layers of drywall about an inch away from the existing metal stud wall which had 5/8" drywall on both sides. Before building the wood stud wall, I removed the layer of drywall facing our space so as to stick to a two leaf wall. This wall was built using the methods recommended on this forum with acoustic caulking and gaps at corners to decouple walls and ceiling etc.

This has reduced noise leakage from the space next door dramatically, but we still have some mid and high frequency leakage. I'm not exactly sure how much. It won't register on my radio shack spl meter. If I had to guess I'd say maybe around 35 decibels SPL of leakage when things get noisy over there. I have determined that this sound is traveling through a 6 inch sprinkler pipe which travels through this new wall I built and into the neighboring space. I should have known that this would happen, I guess I just didn't realize how much the sound the pipe would transmit. I know that getting rid of the pipe isn't possible. Its required for the building because of the nature of the neighboring business. It isn't very feasible to box it in since its about 8 and a half feet from the floor, while the ceiling is at 12 feet and the pipe travels all the way across our space and then almost the whole length.

Therefore I need to find a way to damp the leakage. Possibly also to do some damping before the pipe enters our space. I think that our landlord (the occupant of the neighboring space) would let me do that.

I've been reading on this forum about the need to use constrained layer damping with something as rigid as a sprinkler pipe. I'm thinking of using green glue around the pipe with something over it to get this damping. I'm wonder if mass loaded vinyl would work in this situation. But perhaps its not rigid enough to cause adequate damping. Any ideas about the right materials to use to damp this sprinkler pipe? Thanks for your help. Let me know if I forgot any pertinent details.


Author:  John Sayers [ Tue Aug 04, 2009 6:49 am ]
Post subject:  Re: need help with flanking problem via sprinkler pipe

josh - have you tried wrapping the pipe in that blue insulation you have?

Author:  yosh [ Tue Aug 04, 2009 7:51 am ]
Post subject:  Re: need help with flanking problem via sprinkler pipe

I haven't tried wrapping the pipe in that insulation. If anyone is curious, it's the Ultra-Touch Cotton insulation. One thing that concerns me about that is condensation on the pipe causing rust problems. Maybe I shouldn't be worried about that? Humidity is high in this part of the world. I have an HRV and a mini split that will be helping me control humidity, but in the winter especially I will be running a dehumidifier to keep the 60%-70% average humidity down. What if I wrapped the pipe with plastic first?

Do you think that the insulation would provide significant damping? Or just help with transmission loss? If it was just helping with TL it seems that I would have to wrap all the pipes since the sound seems to very easily travel down the pipes. It would be a big project, and I'm not sure about how it would look.

It was my hope that, if I was able to damp the pipe enough before and after it crosses between the two spaces, that this would control transmission enough to not have to treat all the pipes - just those sections. I don't know if this is a realistic goal or not.

Thanks for your input!


Author:  SimonOstheim [ Wed Dec 01, 2010 9:10 am ]
Post subject:  Re: need help with flanking problem via sprinkler pipe

hello and sorry for digging up such an old post.
i do have a very similar problem considering pipes that (have to)
go through the walls because my landlord wont let me
move them. so i wanted to ask if you had any success in
dampening the sound transition though the walls via the
pipe and if what you did...

thanks a lot for your reply

Author:  yosh [ Wed Dec 01, 2010 10:47 am ]
Post subject:  Re: need help with flanking problem via sprinkler pipe


I did have some success in reducing the sound transmission through the pipe. I certainly did not eliminate it, but it is significantly better. I wrapped the pipe in R13 cotton insulation. Then, because I didn't want just a bunch of insulation hanging out up there exposed, I wrapped aluminum flashing around the insulation and taped it in place. I didn't treat the whole pipe, just the first 22 feet of it before it turns a corner. The turn in the pipe seemed to reduce sound transmission past that point.

Hope this helps. Let me know if you have any questions about it.


Author:  gullfo [ Wed Dec 01, 2010 12:10 pm ]
Post subject:  Re: need help with flanking problem via sprinkler pipe

couple of thoughts - one, Mason Industries makes a variety of pipe isolation products to help with decoupling the pipes from their supports and sealing wall penetrations; two, as suggested, insulation - preferably something which can withstand moisture and still breath enough. one project we added some weighted angled brackets w/ screwed on rubber blocks on the various segments of the pipe to "counter balance" (dampen) resonances which were related to the various lengths. ultimately some sound was still transmitted but not significant compared to what it was before. in other projects, building soffits was the only way to get the isolation needed (pvc drain pipes are the worst...)

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