Hi all.. I'm designing a small home with high R-value walls etc, and one builder has suggested SIPS. But I'm concerned about their low STC rating. Any experience out there? People living in them? I was thinking of a layer or two of Green Glue/dryall on the interior, but still wondering if I should go with a different type of wall to start with. I really want a quiet house. Thanks!

I’ve had several people tell me that my house (SIP’s) is the quietest house they’ve ever been in, and I haven’t done anything special.

It really depends on the noise level where you live. If you’re out in the country, with no close neighbors, railroad or highway, you’re going to be just fine. If you’re in a neighborhood, with no heavy traffic, you might be just fine. On the other hand, if you have a major highway on one side of your house and train track on the other, you have quite the challenge.

For the moment, I’m going to assume that your new house will be in a normal residential area, and have the normal residential sound level of occasional traffic, kids playing and lawn mowers, and you want an exceptionally quiet home. I would recommend at least 6-1/2 inch SIP walls, with a layer of ½” or 5/8” Quiet-Rock drywall on the walls, using Green-glue. One sheet of 5/8” Quiet-Rock has the sound deadening quality of something like 10 sheets of standard drywall. The Green-glue is rubbery, and dampens the sound. You might even consider the use of Quiet-Rock on the ceiling to further reduce sound penetration. Another issue that must be dealt with is the windows. Windows can transmit quite a bit of sound. Triple pane windows, or windows specifically made to suppress noise may be needed. You could build the house first, see how noisy it is, then if needed, add the Quiet-Rock.

If your faced with a serious noise situation, ICF's may be a better choice.

Steve
GrandCountySIPs.com

Steve, Does the type of SIP have much to do with noise transmission? Would OSB skins over EPS conduct the least noise? I have not had any noise complaints with metal skin polyurethane filled SIPs but that may be because of the quiet area instead of the type of SIP.

Your choice of exterior finish can help with sound transmission too. If you were going to use lap siding for instance, choosing 5/16" fiber-cement board siding over vinyl siding would be a better choice for sound control. The key is to add mass back to the structure. However, your choice of window and door will be a higher priority as regards residential exterior to interior sound control.

Alton,

You know mass and density have a lot to do with sound transmission. Most OSB SIPs have a 1 to 1.5 pound per cubic foot density EPS foam core and PU foam core metal SIPs have a density of 2.4 lb/ft^3 which is about double by weight. With the give and take between skin thickness and foam core density, I think their performance would be very similar to each other. This is an educated guess.

PU foam cores almost always seem to be of a higher density in SIPs than EPS foam cores. So, in terms of sound transmission being related to density/mass of a material, a 7/16" OSB skinned panel with a PU core will outperform a 26ga steel skinned panel with PU core of a similar overall thickness, but a 1/2" fiber cement board panel with PU core will outperform both. Just my opinion.

This link on STC ratings maybe helpful : http://www.stcratings.com/

If you read the link (Read Weaknesses), STC of a material is not the 'be all and end all' of sound control.

Alton,

SIP's seem to do a good job stopping high frequency noise, but don’t seem to do as well with low frequency noise. High mass walls do a better job stopping sound than low mass walls. If you had an extruded polystyrene wall that was the same thickness as an expanded polystyrene panel, the extruded panel would be quieter. Would a steel SIP panel be quieter than an OSB panel? I think so, but I can’t prove it. I think the difference would be minimal. Sound is vibration, and if the interfering material transfers the vibration, it’s noisy, but if the material subdues the vibrations, it’s quieter. Concrete (high density, high mass) does a good job of sound reduction. The more mass you can add to your wall (concrete siding, Quiet- Rock, and an air gap to stop vibration transmission) the quieter the house.

Steve
GrandCountySIPs.com

Our experience using 1-1/2" steel hi-hat over SIPs creates both a wire chase and dead air space greatly improving sound transmisson ratings. We also prefer 6" walls that make for a quieter wall ...............

Thanks for all the swell replies...

I spoke to the Green Glue company yesterday regarding SIPS, and they had done some testing. The naked SIP performed poorly (STC 22), which is less than a standard 2 x 4 wall. Then they added drywall (1 sheet, no GG) and it went to 31. They added a 2nd sheet of drywall, and it was 33, which is still not so good. And oddly (and odd that they'd admit it), they added GG in between the drywall layers, and it didn't add much if any improvement(!) Then they tried adding GG and a sheet of drywall to the EXTERIOR of the SIP, and it shot up to 61! Of course you wouldn't do this in real life, but you could probably get a decent result with another layer of OSB and GG instead of the drywall.

They also tested using an interior metal stud wall, 24" on ctr, with fiberglass batts and an air gap of 1" and 2 layers of drywall and GG in between, and got STC of 54. This might be the best way to go, as you then have a nice chase for wiring etc, and even higher R-value on the wall assembly. The next question I'd have is how it would perform as far as moisture goes. I'm no expert, but I don't see a big problem. Any comments on using a poly vapor barrier over the studs/batts?

Thanks again!

The test Green Glue did showed that your choice of exterior finish on SIP walls matters and can create a superior sound controling exterior wall.

Metal studs on exterior walls act like heat sinks and are not the best choice for energy performance.

Simon..

I agree that the testing suggests that something with some mass like cement board would probably help SIP's STC rating. Not sure what you mean by metal studs being a problem in this case, as they'd be inside the SIP enclosure....(?)

pbrane,

I thought you were going to do away with SIPs altogether and just use metal studs as your exterior wall. Sorry for the misunderstanding.:-) You should look up 'Resilient Channels', which are metal furring channels designed for sound control and are not as deep as metal studs.

An STC of 61 for a SIP wall is excellent and loud speech would be inaudible from one side to the other. I think the code requies an STC of 50 for party walls in an attached living situation, so 61 blows that away. Most 8" block walls only achieve 48-55.
 
There are exterior grades of gypsum board (drywall) that you could sheath over the exterior of SIPs, but you would have to place a moisture barrier like building felt between, which would probably function almost as well as the Green Glue in terms of vibration absorbtion, if you used a heavy grade. However, your climate conditions could make this undesirable.
 
By the way, what are your climate conditions? Is the house going to be in a typical suburban residential neighborhood? Any specific noises you need to block out? (eg: aircraft flight path, train crossing, interstate highway nearby)

If you understand the mechanism by which Green Glue works, then you can design a wall system for sound control. The Green Glue creates a flexible vibration absorbing gasket between the rigid materials. Rigid materials transmit sound and flexible materials that allow movement mostly don't. So, just apply your finishes over the SIPs with gasketing at the attachment points between materials. If you add air spaces, even better.

Here are some current 'factual' baseline STC numbers for basic OSB SIPs. Click link:

http://www.portersips.com/d...s/0115.pdf

These numbers can be easily and cost effectively increased to perform as well as masonry for sound control. I suspect metal SIPs would have similar numbers as the above.

Your exterior finish is the 'front line' for exterior to interior sound control in a home. It absorbs/reflects the highest amount of sound energy, so choose it carefully. For instance, cement stucco over wire lath is a common finish and would be a good one because the cement has mass and density and the wire lath that attaches it is flexible and will further absorb sound through movement, transmitting less of it to the SIP.

You can request to have the SIP system tested for sound.

Posted By jumpingspidermedia on 01 Aug 2011 11:23 PM
You can request to have the SIP system tested for sound.

Thank you for always pointing out the obvious

Thanks for the input. I'd like to use stucco, but it's a little pricey. I got quotes from $5 and up /ft2 for the "real" stuff. I suppose I could use cement board, but I'd really like to use cedar.

Can anyone address the potential of using a water & ice dam material between the exterior SIP walls and the exterior finish, e.g., cedar plank, T-111, Hardi Plank, etc.? I may have mis-named the material, but it is a sticky rubber-mat material that is often used under the first course of roofing shingles to stop the "wicking" action of water as it comes of the edge of the roof.

I am currently planning to build a SIP house in Angel Fire, NM and hope to address all of the various issues of this building methodology. Thank you in advance for your response(s).