[cuba_pete]

I've searched the site and read many posts, understand many of the concepts of soundproofing (I work in electro-acoustics), and have scoured the internet for over a year doing research, and more intensely recently.

Here's the background:

My home is in an extreme high-level noise area due to the military flight path from a nearby airfield (I regularly measure 114 dB during flight ops at my location), and the incidence of high-noise periods is set to increase over the next three years (barring the successful attempt of the WA state AG and his and other lawsuit(s)).

I will be staying where I am, and upgrading my home for the long haul.

I understand the ceiling treatments and have taken some measures there. I've replaced my windows with STC rated units.

There doesn't seem to be a one-stop-shop for resources regarding soundproofing the roof. The sites that I have visited usually narrow down to the ceiling of the home, neglecting the echo chamber above it. I have used various test methods to determine that much of the noise enters the living spaces via the roof structure.

I need to replace my roof(s) (two on a split-level home) within the next year or so as it is, so I want this project to cover this base without regret or re-work. All roof and soffit penetrations i.e., attic ventilation, chimneys, bathroom ventilation, etc. will also be part of this project.

I haven't found serious evidence of anybody researching and sharing information like this in our area. As much as I learn through this project I want to be able to share with the community since we are all in the same boat.

Here's the question:

Has anybody dealt with a contractor or done work themselves regarding soundproofing a roof? I have a great GC friend, so when I approach him I want to nail down, so to speak, some more ideas and get his twist as far as what materials he can even get access to or is willing to install. I am willing to DIY as much as possible, if not the entire project.

If you have experience in this area or know of any such project I would like to hear about it.

 

[Bud9051]

No direct experience with homes but have worked with sound issues at my prior job, Bell System. One option that might help would be converting the attic to what we call a "hot roof". It involves air sealing the attic eliminating all ventilation and moving the insulating layer to directly under the roof. There are more details to it, but it is often done and well documented.

A hot roof would eliminate the sound entering through vents and greatly reduce what the ceiling plane needs to deal with. From what I have read it usually involves application of spray foam.

Bud

 

[cuba_pete]

This is actually the direction I am going, makes the most sense. Thanks for that...it eases my mind a bit to know that someone else is thinking the same way. There is actually a roofing contractor near here who advertises this on his web site.

I am "designing" a whole house fan system which will exhaust through a gable vent. This will have tie-ins for the bathrooms as well. It will have ventilation silencers and tuned elbows for frequencies between 125 and about 4000 hertz. I am still taking measurements to determine the best frequency ranges for tuning the ventilation system.

I am looking at open cell foam on the underside of the roof.

Working with a contractor and codes would be the sticky bit. As long as I don't exceed 10 pounds per square foot on the new roof, I won't require a building permit. The extra stares I get from the pros, county, and state aren't required or desired. However, I also want to make sure the trusses can handle another layer. Leaving the existing shingles in place adds to the sound deadening. I also understand that I may not be able to leave the old shingles due to weight, code, or whatever. I am okay with that as long as the new roof increases the STC.

It seems like a balancing act between ripping off and putting down, which would be great to contract out. But if the new roofer stalls when I say "no vents" and they talk about no guarantee or warranty due to the ventilation...hmmm. Then again, if I do it myself, I don't get a work warranty either.

I am still undecided about the roofing itself...whether to use some type of coated/textured standing seam metal over rockwool battens. My slope is somewhere between 30 and 45 degrees. Eliminating the ridge vent entirely might require new decking, though.

 

[Bud9051]

Your thinking is bouncing all over the place. When considering a sealed attic with a hot roof I believe you need closed cell, but do your homework. That attic then needs to become conditioned space which then requires that spray foam to meet your local region insulation levels. what is in the ceiling no longer counts.

Google and read many articles.

Bud

A personal note, when someone is wanting to avoid permits I get concerned about future value and performance. But none of my business, I'll leave you alone.

 

[cuba_pete]

Your thinking is bouncing all over the place. When considering a sealed attic with a hot roof I believe you need closed cell, but do your homework. That attic then needs to become conditioned space which then requires that spray foam to meet your local region insulation levels. what is in the ceiling no longer counts.

Google and read many articles.

Bud

A personal note, when someone is wanting to avoid permits I get concerned about future value and performance. But none of my business, I'll leave you alone.

"Bouncing all over the place" can also be stated "considering all angles". The entire roofing system from the ceiling to top of the vents is all part of the system. I can't change one without considering the impact on all parts. That is why I started this thread asking for people who may have actually done this before.

The open cell foam is approved for attic spaces and is better at sound attenuation, though its R value is nearly half of closed cell. My ceiling is already well insulated, so I am not looking to insulate...just attenuate the sound transmission of the roof. Either way, closed cell is not as good at attenuating sound. If I am using an MLV, Acoustiblok, DeltaTrela, etc. underlayment (reducing restriction on, or eliminating the ability to use foam) type in conjunction with the foam the STC increase will come closer to meeting my needs.

I am not wanting to avoid permits, but having to explain to the contractor, county, state, and finally the federal board is very difficult when you have to face each one independently. You know how some inspectors/AHJ's are when met with things they've never seen before and have zero desire to understand. I went through that process a few years back when I just wanted to put up a simple unimproved pole barn. I had to get the style and colors approved by the local federal reserve board twice, adding about six months to the project...and that was with the contractor going to the board...who was quite familiar with the process...the board only meeting every two months.

If I have all of my ducks lined up ahead of time using, in part, the experiences of this forum's users, I hope to avoid pitfalls or shortcomings.

 

[Bud9051]

Open cell foam is also vapor permeable and can allow moisture vapor to reach the bottom of a cold roof and cause problems. That would normally be up to your local code authority but apparently they will not be in your loop.

Bud

 

[cuba_pete]

Open cell foam is also vapor permeable and can allow moisture vapor to reach the bottom of a cold roof and cause problems. That would normally be up to your local code authority but apparently they will not be in your loop.

Bud

With the proper attic ventilation up to and including conditioning, yet to be seen are alternative systems suggested, the open/closed cell decision is still open-ended.

I see what you are slanting at, and not that it matters, but I am not cutting them out of my loop, but don't need authorities completely shutting down anything but their cookie cutter methods.

That's one driving factor as to why we don't don't have any soundproof roofs in our area. Our Washington state Attorney General is suing the US Navy due of the loudness of the jets. If I can find a builder or GC who is willing to get a workable solution with regard to high STC rated roofing to our area, then we can spread the word to the locals about a possible helpful tool to make the co-existence more livable.

If I can find a STC-improved roofing solution that works with codes and AHJ's who are willing to listen, then I am in a win-win.

 

[huesmann]

The sound isn't coming only through the roof...your walls and (especially) windows are probably big transmitters too.

 

[cuba_pete]

The sound isn't coming only through the roof...your walls and (especially) windows are probably big transmitters too.

The walls and windows are done, as well as the ceilings, thanks.

I am looking for specific information for the roof.

 

[Windows on Wash]

Uncouple the framing. Fill the interstitial spaces.

What does the roof and framing consist of?

 

[cuba_pete]

Uncouple the framing. Fill the interstitial spaces.

What does the roof and framing consist of?

It's typical stick construction and composite shingles.

If I had the money, uncoupling the roof structure from the house would be a great option. I am, however, looking at uncoupling the decking from the trussing/rafters. It would be an extra cost, but if someone out there has done this, similar to how interior walls are soundproofed, that is what I am interested in. I am also having the ventilation system designed differently to minimize roof penetrations, which would bypass the soundproofed roof.

I have regular fiberglass insulation in the attic now with an added double-thick layer of blown in by the previous owner (about 24" in some areas), which does some sound absorption. I am also looking at open/closed cell foam or additional rockwool batting in the attic space.

btw...

Just this morning I got a quote back from an Alibaba source for mass loaded vinyl to be used in concert with the roof underlayment...direct from China (which is where the big US roofers get it, ultimately). The cost was over $17, 000 because they wanted a huge quantity to ship...way more than I need. I am not looking to become an international importer over this one project. If I use MLV for the new roof, I will likely end up buying it local anyway.