EPDM gaskets instead of ZIP System?
ElPotrilloDeGringolandia
| Posted in Energy Efficiency and Durability on
I was wondering if anyone has tried using EPDM gaskets for air sealing exterior OSB instead of taping the seams? EPDM is cheap, easy, can be put up in the rain, super durable, etc. I am going to lunch or I would explain more of my strategy…
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Spencer,
First of all, Zip System sheathing has several benefits beyond the ability to provide an air barrier. Zip System also works as a WRB.
I'm not convinced that installing EPDM gaskets under every sheathing seam is (a) easier or (b) less expensive than using tape. For one thing, what about the "Oops! I missed a seam!" problem? At that point, you would have to remove the sheathing to insert a gasket under the seam you missed. That isn't easy.
I'm sure the ZIP system has many benefits. It wouldn't be very hard to make sure you gasketed every seam....you know where your panels are going to land before you start putting them up. It should be pretty easy....you just have to staple them up and away you go.
My question is though, has anyone tried this before?
Thanks,
Spencer
Spencer : out of curiosity, what is the goal of using EPDM gaskets VS the special tape method ??
Are you afraid of their tape not holding up ?
Spencer, I have not used Gaskets...
However, I believe there is a "future" for developing some good Gasket techniques
Including gasketed structural sheathing and gasketed drywall.
I have recently started working with the local H for H and I am considering experimenting with "gaskets"
I can not open the links/files that you posted.
Thank you for the response and the pictures. =) I can't open the files either. I have not had good luck attaching things on this website in the past. I will try again. If you would like I could email them to you as well.
Ok I checked and that one let me open it. Here is the second.
Well I just don't understand why this will not work. I got the first one to work, but the second is just not happening.
All right I renamed it. We'll see if the problem was the ampersand in the title.
Yup that seems to be what the problem was. Now it should work.
Spencer,
I have some experience working with the gaskets you're specifying and they have worked well for me.
I've looked at your details...
Maybe I missed something...
How do you propose to seal the horizontal seams between sheathing panels (ie, where they aren't backed by framing lumber)?
I guess I should specify that this is an 8' wall so there shouldn't be any horizontal seems that aren't backed. However, a number of things could be done for 9' walls. 10' sheets of plywood could be ordered, 9' sheets could be used with a strip of plywood over the rim, or I suppose blocking could be used to back the seams. You may also be asking this because you run your plywood/osb horizontally instead of up and down. Is that the case? You would normally block behind those seams right?
I appreciate the feedback. How have you used the gaskets?
Thanks,
Spencer
I have attached a couple details that well detail what it is that I am trying to do.
The goal is to use something that is easy, cheap, verifiable, durable, can be done in the rain, can move with the framing, fill large gaps, can be done by home owners, simple, etc. It's like pulling teeth to get a contractor to do anything that entails doing something different than they have in the past so I want something that wouldn't be scary.
Thanks,
Spencer
John, would you try the lower last two pdf's I posted for me? I just deleted the original ones that didn't work because I had an ampersand in one of the titles. The lower ones still work for me but I am curious to know if they don't work for other people.
I will email you them too,
Spencer
Maybe just something incompatible ...or quirky on my end....
when I first open the PDF's ..all I see is gray
then I "refresh" and they are visible
thanks for the email... they open just fine
Spencer's detail:
.
Hi Spencer, I was able to look at your wall detail briefly....
but now ... I can not open any of the PDFs you posted
How far apart would you space the nails when nailing sheathing over the gasket?
Spencer,
I've used gaskets from Conservation Technology under bottom plates, at vertical seams between wood framing and concrete, around window frames in ROs and several other odd applications.
You're right that these gaskets are high quality and durable, but they aren't exactly cheap.
I suppose that you could devise a system to use these gaskets to create "airtight sheathing"...
But I'm a little skeptical that it will offer any real advantages over using a high-quality tape.
The nailing pattern would just be the IRC standard panel edge nailing.
I guess I mean cheap as in the cost doesn't add up to much. I just did some rough calcs for just the drywall gasketing that would be needed for an 1,120 square foot house I am working on right now. It would take about 1 roll of the bg32 or $60. I think you are correct though in stating that they are not necessarily cheap measured in cents/ft and compared to other methods. I just looked real quickly and tyvek tape is around $.07/ft, the drywall gaskets are $.18/ft, and the other one I spec'd for the vertical panel joints is $.36/ft. I can't remember what spray foam or caulk is per foot, but I know I've figured it out before. Caulk should be really cheap....but then again you get what you pay for.
I have Probuild working on the cost of a roll of the Zip Tape right now. Someone on here probably knows. As I suspected in my town they had no real idea what it was or what the Zip Sheathing system is. They knew of the flooring but that was it. That is another reason why I would want to try this.
Can anyone give me any specifics on what the Advantech System costs per sheet? I would be really interested to compare it to Plywood/OSB. I see they have a calculator on their website...but I don't really feel I could trust it.
Thanks,
Spencer
Okay I just got the answer back from Probuild on tape cost. The roll cost is $34.18 and it looks like a roll is 90ft which equals $.38/ft....so slightly more than the most expensive gasket I spec'd. Cost of materials I don't think though is a big deal in this case...it won't add up to much and they seem to be the same cost or less for the gaskets.
I just noticed that ZIP sells a 1" thick nailbase sheathing with foam. Pretty cool. Does anyone have any idea what it costs per sheet?
Spencer,
I was just thinking that for a gasket to work, it has to be compressed to some extent in order to fill the irregularities in the two mating surfaces. With a sheathing material that can bend, the gasket compression will be greater at each nail than at the furthest point from a nail.
It is also possible that the compression of the gasket at each nail will actually lift the sheathing between the nails. The nails will draw the sheathing into a dip, and the dip at each nail will tend to create a reaction between the nails that will bulge outward.
Also, part of the strength of sheathing is in the flat, face to face contact between the sheathing and the framing face. A nail forces those two surfaces tight together, whereas you lose that tight contact with an intervening cushion created by a gasket. This subjects the nail to bending under a racking loading.
Also, a pneumatic nailer will tend to sink a nail into the sheathing without necessarily compressing the gasket because the high velocity of the nailer.
That is a very thoughtful answer. I appreciate it. Something to think about. The panel edge nail spacing is pretty close and the gaskets are pretty malleable. However, the constant pressure of the gaskets pushing out could cause the nails to back out over time. Very good thoughts. Very constructive.
Spencer,
If you were to use the drywall gaskets, I wouldn't worry to much about the nails backing out - although Ron's point about the sheathing not being in tight contact with the framing is an interesting point...
Not sure if that would have a meaningful effect on the final strength of the wall...
Something else to consider...
If you were to try airtight sheathing at the roof using gaskets, that would mean balancing among open rafters or trusses - maybe not-so-bad for an experienced framing crew, but maybe outside a homeowner's "comfort zone".
Spencer,
I was thinking about some of the criteria you layed out in an earlier comment:
Not that I want to distract from your investigation, but why not a high quality tape and conventional plywood?
A taped plywood air barrier is easy, verifiable (moreso possibly), durable, can move with the framing, will cover large gaps and can be done by [motivated] home owners.
That just leaves cheap and can be done in the rain.
Gaskets at $.18/ft and $.36/ft are probably only marginally less than a good tape.
Here is a roll of 3M's 8067 (4") from Amazon at $.36/ft.
The 4" works well for this application - 4" width for corners, but easily "rips" along the split back to make two 2" pieces for seams and better value.
There are also other tapes at similar price points like those from SIGA or Pro Clima.
My plan is only to use it for the walls, not the roof. I figured out the costs for the zip wall system and it boils down to....well materials just don't cost that much even if the zip system (including tape) is $30 a sheet and OSB + tape + Tyvek is $15-$20 a sheet. The cost to install the system will probably be the most important factor for most home owners. I took a closer look at the system after calculating the costs and it looks pretty cool. I have changed my details to allow either...but I think a combination of both would be what I end up with ultimately. This is because you still have to seal the bottom and top of the panels....their own details say to caulk, gasket, or otherwise air seal the untaped edges.
I think taping the seams of regular plywood would be great...one question though...I don't like OSB but it seems to be what everyone wants to use even if I recommend against it...can you tape OSB reliably or is it better to tape plywood?
Thanks a lot for the thoughtful responses. Not getting crapped on makes these conversations way more fun.
Spencer
Spencer wrote:"This is because you still have to seal the bottom and top of the panels...their own details say to caulk, gasket, or otherwise air seal the untaped edges."
I think you make a good point.
A while back I started up a discussion similar to yours....warning-it's a long thread ...but I did get some interesting feedback
https://www.greenbuildingadvisor.com/community/forum/energy-efficiency-and-durability/19107/airtightness-sans-sprayfoam