Window flashing/housewrap problem
Installing some very expensive Marvin windows to replace 20-year old home-made hippie jobs. Two questions:
1. The current practice seems to be install housewrap, then windows, then flash, then siding. OK, but there will be a delay with the siding (cedar shingles) for some time. Should I worry about UV degradation of the Tyvek? Put on an additional layer (or felt) when I or others shingle? I already have part of the house Tyveked and exposed to the elements for about 4 years. The Tyvek has definitely faded (I mean the lettering).
2. Marvin says not to use asphalt-based flashing tape. All we have here on the island is Grace Ice and Water Shield (bituminous, asphalt) and that is what the contractors seem to use. Should I go with this local practice, defying Marvin, or should I try to find a butyl membrane, for example?
Thanks. The window thing has become very complicated over the past couple of decades.
Replies
I'm watching this thread w/interest because I will be doing the very same thing (sooner rather than later, I hope).
New neighbors avec small child & dog in the bad karma house next door. Fingers crossed that salt was tossed & sage was burnt during the badly needed renovation. (And I am NOT bitter about not being able to buy it, tear it down & increase my acreage...well almost acreage)
Might as well pull the tyvek off the house when you side it. Tyvek is only good for a max of 6 months of exposureto the sun. Buy the tape the window man. wants you to use. There is no sense in giving them a reason if you have problems to reject, because you used the wrong tape.
I prefer to use tar paper behind shingle or cedar claps, there has been a problem with tyvek behind cedar products.
Theres something bout the acids in cedar and Tyvek dont go together but other products like Typar are ok, because they are a little different. After reading around here you should consider felt too. But definatly get rid of or go over the old stuff it cant do its job anymore.
Get the proper flashing tape, If your local yard sells Tyvek then you should be able to get the tyvek tape that isnt asphalt based, what island would this be? If you gotta wait for the siding anyways wait for them to order the tape.
I thought Typar was a brand of Tyvek? If I pull the old wrap off, then add felt or new house wrap, just butt it up to the window casings or try to get it under? I'm asuming that the wrap under the casing, which hasn't been exposed to UV, is still doing its thing.There has been much talk on BT about Tyvek/felt/cedar, but I haven't sensed a resolution, and a recent FHB shows cedar shingles going up over housewrap.
Couldnt tell ya the science of it but they are not the same animal at all. If you have ever used both its obvious.
I looked again -- my wrap is Typar, not Tyvek. But FHB, September 2008, p. 70, has an article on storyboards. The photo shows two guys installing cedar shingles over Tyvek. not Typar.This issue has been beaten to death on BT, but I still don't know what to think. It's almost as bad as the numerous threads on collar ties.
The typar rep would be very disappointed in you...well, more so their marketing people. Who names a brand that close to the other?
Typar and Tyvek are totally different materials with totally different properties. Check out the science behind it something if you really care -- I've seen the presentations and still couldn't tell you where one is better than the other! LOL."It depends on the situation..."
<< Typar and Tyvek are totally different materials with totally different properties. Check out the science behind it something if you really care -- I've seen the presentations and still couldn't tell you where one is better than the other! LOL. >>
I researched this topic at length a few years ago, so I'll break it down for you. Both Tyvek and Typar are spun-bonded polyolefin (same basic material "sewn" together in the same basic way). The perm ratings of each are different (Tyvek: 58; Typar 12). The real difference between the two is their resistance to surfactants (surface-active contaminants). These water soluble extractives are most commonly a problem with cedar and redwood siding. The surfactants basically change the surface tension of water, allowing it to pass more easily through the housewrap.
University of Massachusetts buidling scientists did a study on this years ago and they found that Typar had superior resistance to this problem compared to competive brands. Why? I have no idea on that one...I guess only Typar knows the secret formula.
FYI - other solutions can cause the same problem - soap, power washing chemicals, and even some types of latex paint. Housewrap has weak spots.Justin Fink - FHB Editorial
Hey PenobscotMan: Danno is right I work on many old homes and cedar and felt go together. Check with the Cedar Shake and Shingle Bureau and they only recommend felt paper under their products. I see a lot or rotted cedar here in Northern Michigan with Tyvex under it. Builders try to prime all sides of the cedar thinking that this will help but it won't. Use felt and do what Marvin Window Company wants. You can't go wrong. Good luck on your project and make it fun. Best regards, Dale Buchanan
OK, but if I use tarpaper, which is asphalt-based, then I am violating Marvin's warning, because the naiing fins will be in contact with the tarpaper. The problem seems insoluble to me! Arrgh!
Pen: Use felt under the cedar and just cut strips of housewrap about 4" wide and install over the felt just around the windows. I hope this helps. Regards, Dale
Edited 9/2/2008 7:56 pm ET by Harborman
Well I guess in theory you could run the felt like normal, then line the window sill with the proper flashing tape, then line the sides with some of the old tyvek there by breaking the contact issue. Finally taping the rest of the window. Just isolating the felt from the window, a pain maybe but not huge problem, keeps all the manufactures happy and your covered if any warranty issues come up, I guess is worth a couple of minutes if the company cant void the warranty and homeowner cant look for you to fix it for nothing.
I think on a new building situation when using cedar look at typar because that's supposed to be ok, I also notice that most of the housewraps that the local yard sell that has their name all over them are usually typar, although I have seem one that was tyvek.
Leaving Tyvek for 4 years seems suicidal. If it's installed correctly it's behind the window flanges. Too much exposure will wear it out, and how are you then going to replace it correctly?
I don't think they mean you can't put the window flanges in contact with asphalt felt, but I suppose a call to Marvin wouldn't hurt. For sticky flashing, have your supplier order you some Vycor Butyl. If in fact you can't put the felt under the window flanges, then run the felt as normal, run 12" Vycor around the window openings (into the openings and out on the sheathing), install the window, and then tape with more Vycor. Buy some stock in W. R. Grace before you buy all this Vycor.
"Suicidal" -- tell me what you really think!This is all very confusing. The problem with the asphalt seems to be the incompatibility with the vinyl nailing flanges. But why isn't this a problem with other manufacturers' wndows which also have vinyl flanges? And am I truly the first BT/Marvin user to worry about this? I take your point about my sloppiness in leaving the Typar exposed. I work slow. But a very common local practice (rural, coastal Maine) is to sheath a house in T-111, install modern windows (Andersens, etc.), add 5/4 flat casing, then some time later side with shingles, when time and money become available. I understand that this is not the best practice, but we are not talking about housing for the rich here. So, maybe, this is how to frame the question: if I am not going to shingle the house for a year or so, how should the window RO be prepped, and how should the flanges be taped?
You are correct to be concerned about the vinyl flange/asphalt flashing issue. It sounds like you actually read the instructions.
The instructions with Tyvek probably tell you how long you can leave it exposed. Four years will probably render it useless. Placing raw cedar over it will likely be a problem also.
There are two different types of vinyl flanges.
A typical vinyl window (ie Milgard) has stiff integrated nail fins. AFAIK, you may use either butyl or asphalt sticky flashing with these fins. The caveat in this situation is that some sealants will react with your sticky flashing. If you use the incorrect sealant behind the nail fin, and it contacts the sticky side of the sticky flashing tape, you will see black streaks at the bottom corners of the windows after a couple of years. This is the deteriorating sticky tape.
A marvin fiberglass window has plasticized vinyl nail fins. (at least the Marvins I installed this year do). Plasticized vinyl is flexible, (think vinyl siding). It is the plasticized vinyl that reacts with sticky flashin tape. Someone correct me if I'm wrong. I deal with these issues everyday, installing several different brands of windows on several different types of houses. After reading the warnings from the window manus, the sticky tape manus, the housewrap manus, I've determined that it is impossible to comply with every manufacturers requirements.
I haven't even mentioned yet what the spray foam will do to some materials.
David Franklin
bandbcontracting.net
AAMA certified
Licensed GC
You are right, the Typar can't be left as is. Hosuewraps vary, but typically 3-6 months is all they recommend before it's shot from UV damage. But you don't have to remove it as everybody is suggesting, you can add a new layer right over the old with no ill effects.
As for the window flanges, follow the Marvin install instructions to the letter. If you care enough to post about it here, then you care enough to take the time and trouble to use the right product. If your local supplier can't get it for you, consider internet resources to find a few rolls.
Justin Fink - FHB Editorial
"No ill effects" -- but some BTers think that Typar will cause the cedar shingles to explode and fall off (LOL, sorry). The editors of FHB must not think that, as they prominently display fotos with cedar going on over housewrap (September issue). So, anyway, probably the conservative course of action is to cover the degraded Typar with felt when time comes to shingle. Or hack it off and add felt. (All this is in part of the house with windows installed a few years ago.)My CURRENT problem with the Marvin windows is, since I don't plan to shingle this year, should I install housewrap, wrap the ROs with housewrap, etc., as per currently accepted best practice. Since everyone agrees that Typar doesn't last, the answer would seem to be NO.So, I plan to seal the RO's with Grace Ice and Water Shield (fabricating a sill pan), install the windows, flash with non-bituminous tape which I will get somehow (probably involving a ferry trip and taxi!). When I shingle, I will use felt. Not sure how to detail the junction between the felt and the flat casing, but when I get to that point, I will ask advice from the usual source: you guys on BT! Thanks.
your plan sounds fine, except I don't agree that Typar won't last under cedar shingles. I have seen Tyvek degrade, but Typar is a different animal. If you are at all worried, felt would be a good alternative. In fact, I was just at the HD buying some supplies for tomorrow (replacing a deck ledger) and I'm not sure I can swallow the price of housewrap anymore. The small rolls are almost $60!Justin Fink - FHB Editorial
Never understood this critiscm of Tyvek. Replaced some woodpecker damaged boards on a house I did over a dozen years ago and the Tyvek looks brand new. Did my own house with Marvin's 4 years ago and used Tyvek.
I don't either. What a confusing mess of differing opinions. I'm skipping housewrap or felt until I shingle. I've ordered some Typar tape, which is supposed to have a butyl-based, non-bituminous adhesive. My Marvin rep said all the stuff about asphalt and the vinyl fins was hoo-ha, and everybody uses Grace tape (asphalt) without difficulty. But I might as well go with the "official" Marvin recommendations. Anyway, has anyone ever heard of windows falling out of a house because the nailing fins had degraded? Anyway, I plan to case them with 5/4 stock, which should further secure the windows to the wall. Maybe in 50 years my grandson will have to deal with this. Sheesh.
LOL. Leave it to the next generation.I researched this subject ad nauseum and IIRC that is what brought me back to this forum after initially visiting it when it was first launched. I will try to dig up the exact sources if you are interested, but it was researched at length by the Building Science Dept. at UMass. Tyvek vs. felt is as volatile a discussion as politics during election season.FWIW, I used Tyvek on my house recently, because I was building it virtually solo and needed to weather it in long before the siding went up. Felt would have had to be replaced, where the Tyvek did not. I also used I&W shield around all windows. Tyvek makes a proprietary product for this purpose but it was prohibitively expensive IMO. I have also used Typar in the past and actual prefer it to Tyvek. I've got a cool picture somewhere of my house completely shroud in white Tyvek after a fresh snowfall, quite surreal.edit:
I wouldn't worry about the nailing fins. As you mentioned the casing will help lock it in, and a couple of nails through the jambs wouldn't hurt.
Edited 9/4/2008 9:17 pm ET by TGNY
You should still pin the window to the framing. I have seen way too many window units depending on the nail fin and the interior trim to hold the unit in place. I guess that would be ok if wind did not exist, but I have seen entire units sucked out of their holes in a bad storm.
If you are interested, I could show you haw to hide all of you fasteners in a Marvin.
"It is what it is."
That's contrary to DIRECT experience in multiple cases where we have seen significant degradation of less-than 10 year-old Tyvek under cedar. Once you've seen it up close, you understand.
Use 30 lb felt.
Note that Marvin, for clad, allows Flex wrap for flashing (good product) and requires a rigid sill pan.
Jeff
My experience is on the eastern end of Long Island. I saw it up close, I understand.
TGNY
I recently did a small framed addition on a 15 year old house for a new propane fireplace. The house had vinyl over Tyvek over spruce T&G board.
The Tyvek had deteriorated to the point where it would have been better if it had not been there. It had shrunk somewhat and torn at almost every nail penetration I could see. The crispness of new Tyvek was gone. It felt slick and soft and plasticky. It had barely any more strength than a wet paper bag. I could easily shred it with my fingertips.
The reason it might have been better not to have it there is that there were a couple of places where the tears seemed to guide water into the structure.
I put my new work together with tar paper.
In future, I will be advising anybody and everybody to avoid Tyvek.
Ron
Ron,Different factors, such as climate, prep, wood treatment must play into it's failure then, because I just have not seen as much evidence personally. I have heard others recommend against it as well though.
TGNY
I'm sure you're right that there are local factors involved. I wish I knew what they were.
Ron
Ron,Here is a link that may be of interest to you:
http://www.umass.edu/bmatwt/publications/articles/leaky_housewraps.html
Thanks for answering the question!
That's a very interesting article -- thanks for the link. But, no mention of Typar, only Tyvek, which came out pretty well, as did 15 lb. felt. (I'm going with felt with the current Maine projecy.)It's hard to integrate this kind of research under lab conditions with the field experience of builders and homeowners. We have a house in Buffalo NY, built ca. 1905. Cedar clapbpoard over felt. The clapboards were not back or edge primed. The felt is now pretty crumbly and soft, but there has been, in over a century, no water infiltration. As you can imagine for a house of that age, the flashing is pretty primitive, also no caulk. I've replaced several clapboards during painting with pine which I conscientiously prime all 6 surfaces, but I will be surprised if that last as long as the original boards.Your article really stresses back priming -- but what about cedar shingles? These are traditionally applied (here in Maine) raw, so to speak.
TGNY
Thanks.
I was interested in his note about the effect of soap on Tyvek. I wonder what DuPont has to say about that? I found nothing on their website about soap, but they do say that sodium hydroxide has no effect on tyvek. Lye is the active ingredient in real soap.
Perhaps the author of the study meant detergent?
Ron
I have never seen this without cedar being present.
frammer,
Is this what happens under cedar? Could it be that this happens when Tyvek is put on any wood but not on sheet material?
I don't really care, though. As long as there is the chance of a mysterious and expensive failure, well, what more do I need to say?
Is there any recourse for this homeowner?
Ron
Are you planning to put trim around the windows? If so, you might consider doing that as part of the initial install. The trim will help protect the flashing tape from UV damage. I think I have seen some brand of flashing tape that is actually foil faced to protect from sunlight. Vycor seems to be OK after a few months in direct sunlight, but I'd be a little concerned leaving it exposed for many months. Might be worth looking into. Holler if you want to try a roll of "Protecto Wrap". I'll mail ya some, save a ferry boat ride.
Yes, 5/4 trim. As you say, that should protect the sticky tape.
I am simpathetic to your problem. Marvin is concerned about the reaction between the nail fin and the petroleum in the tape. You could remove the nail fin and use a different install method or isolate the nail fin with something like tyvek tape. I have attatched the install instructions.
"It is what it is."
We just did a job where we tyveked and taped the windows to spec then covered it all with tyvek drain wrap over the taped tyvek to give us an extra drainage plain. not all that expensive to double it up. about $300 for a 2600 sf house.
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"You cannot work hard enough to make up for a sloppy estimate."
All I can say re housewrap as a permanent siding finish, is this.
Far upstate NY, in the northern Adirondack region, in the poorest counties in the state, we have a style of archicture called, "early Tyvek."
Some folks have gotten many years of real estate taxation reduction by building themselves a house, housewrapped only, moving in, and never taking it any further. If they get along with the assessor, he'll wink and apply the "not yet complete" rate to the property improvement.
Some of the wraps likely do better than others in this application. The best answer might come from manufacturers reps who can come up with some engineering data. I was in building products manufacturing, and we did accelerated and long term weathering tests on all kinds of stuff. I'm sure DuPont and others have done the same.
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