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The July 2001 issue (#140) has a response by a DuPont representative to the FHB #137 article about housewraps and a subsequent response by Mr. Lstiburek. The DuPont rep is absolutely correct and Mr. Lstiburek is wrong. If Mr. L were to compare apples to apples he may have a valid argument about housewraps; but he is not making equal comparisons (haven’t you figured that out?)! Of course his homes are going to have less infiltration if he seals around bath tubs and fireplaces; installs draft stops; installs taped rigid insulation and moves ductwork to the building core.
I would ask Mr. L to do the same with 200 houses; 100 using Tyvek and 100 using kraft paper or felts. I would be willing to put money on the Tyvek houses having lower infiltration. I’m shocked that the FHB staff hasn’t exposed the flaw in Mr. L’s argument.
Chad Sutter
Miles City, Montana
Replies
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Chad, I think that the core of Joe's argument is that you'd be better off putting the money that goes into housewrap into better air sealing within the house. Most houses are sheathed with plywood or OSB anyway, and there's not much air that passes through them.
Given that scenario, and the fact that tar paper probably stands up better to extractive bleed of tannins, which act like surfactants to reduce the water repellency of housewraps generally, my own house got tar paper. It might be that tar paper stands up so well only because it's thicker. BTW, from the research that I've seen, Tyvek stands up to the effects of surfactants better than any of the other plastic housewraps.
Andy
*I believe that my framer would have charged me quite a bit more to put up tar paper than he did when using the 10' wide Tyvek, since it has to take longer. I too think it irresponsible for Mr. L and FHB to simply assume that someone who uses Tyvek doesn't also do all the things that Mr. L does to his houses. The kind of "stealth logic" used here to undermine a good product is disturbing. Whatever happened to journalistic integrity?
*Chad, I don't think there would be any appreciable difference in air infiltration rates, if your 200 houses were done properly. If you wrap a house properly in felt, it will be extrememly wind resistant. Tyvek is one of those well advertised consumer products that have garnered more than their share of attention. They've marketed themselves well, but that does not necessarily mean that they are a better product.I've wrapped almost as many houses in felt as I have in Tyvek. There's not much difference in labor. I don't change my price for either. Tyvek is not an easy product to work with. On the large walls, the larger Tyvek rolls work great but felt isn't that far behind. Personally, I wouldn't spend the extra money for the Tyvek. I believe that at some point, houses get too tight. A decent rough frame, without extraordinary efforts to seal, will produce a house that breathes. Add a sensible level of air infiltration prevention effort, and you are fast approaching a "too tight" house.blue
*all the tests i've seen in the mags show that tyvek is the best of the modern housewraps.... but not superior in overall performance to 15# felt..... i did the tyvek bit.. but after the testing came out.. i went back to felt.. and i'll stay with it...the difference in labor is negligeable.. and felt is easier to detail for flashings...
*The folks at Dupont have done an outstanding job of Marketing Tyvek, but for the wrong application. Those of us who build a good product and cover the exterior SOB or Plywood sheathing with felt or an air infiltration barrier do so more to protect the sheathing from water penetration of the siding then anything else. In Maryland where I build the vast majority of the builders don't cover their exterior sheathing with anything other then the finish product. We all know that few siding products are moisture proof and that liquid moisture will penetrate. I for one want something to prevent that moisture from being able to migrate between the seams of the sheathing. Tyvek is a good product, but less for its ability to prevent air infiltration then for keeping moisture out; but then so is felt.What ever you may feel about Joe, he has earned the right to be somewhat opinionated. He has done an outstanding job of making our industry much more aware of the dangers lurking when you don't look at the home as a system.RegardsHoard
*I also have used both. I will stick with the paper. It is a lot easier to detail flashings like Mike said. I also think it is a better waterproofer than Tyvek. Not to mention the price . Factor in the wood tannins and the bubbles that you end up with when installing the 10' rolls and you see why I have made my choice. It is also pretty scary on a windy day up on a pick with that 10' foot roll.
*Well, blue eyed devil, someone finally woke up and smelled the roses about a "too tight" house. You hit the nail squarely on the head. Where are all the rest of the sleepy heads? So many buildings are now so tight that air exchange and internal air pollution are serious factors affecting the residents. Check out the products being marketed now for adding air to a building - their numbers are burgeoning. I guess it's call progress???Cliff. Johnston
*I am not sure I understand this whole concept. Years back the application of Plastic on interior walls was popular which closed in the cavity and started mold and rot. Then a product tyvek was introduced that could breathe and supposedly it kept water or dampness out but air could pass thru it. I did some remodeling work at my oun home and installed celotex foil face over horz. ship lap sheeting and wondered, do I put the tyvek berore it after it? Any way I installed foil tape on the seems and called that good. Mabey that was the worst thing I could have done, like years back when I would jamb the snot out if insulation at windows etc. Thinking I was doing the world some good. When I was a apprentice I had asked the flooring contractor why he was installing shingle felt prior to the oak strip floor. He quickly exclaimed a vapor barrier and I said thanks and walked away thinking what vapor? from where? Thru the years I was told to wrap housewrap into window openings so I diligently in christmass present fashion wraped around openings without knowing why. When you ask ten different people you get ten different answers like a guy I use to work with who said how can insulation stop air infiltration when they use the stuff for furnice filters.
*#15 or #30 felt paper is the choice in my area. Tyvek may be ok, but no one here will use it because of price and lack of experience using it. Felt paper has been tried and true for many, many years.I'll stay with the felt paper.James DuHamel
*I think the manufactures of these house wraps have the public and the utility companies fooled. In my area if you don't use a house wrap , you can't get the $2000 rebate from the utility company. Kind of makes it hard to not put it on the house.DJK
*Chad, I think you need to reread the article , I believe you missed the point. I appreciate people like Joe, who give the scientific facts to those of us who don't believe everything "fortune 100 companies " try to tell us (and sell us). Howard , You hit the nail on the head, that paper or wrap is there to protect the sheating! If you want to control air infiltration , it is a lot more efficient using Joe's technics. And Blue , You got a good point about the house being to tight. Look at all the off gasses from treated wood, plastics, adhesives, carpeting . Lets just put all that in a big plastic bag and jump in , then zip the bag shut. Actually using Joe's methods would cause more concern for indoor air quality.. I don't think the house wraps make houses too tight, mainly because it is rarely installed correctly. I can drive around the county on any day and see house after house where it is being installed wrong. Tyvek intall instructions say to use 1" crown staples or cap nails...well I have yet to see anyone use cap nails , and the only staples I see being used are 5/8" or 1/2" probably cause that is all they got and man those little hammer staplers are fast. Here comes someone putting in a dryer vent..I'll just sawsall a hole through that wrap and the sheating ...stop and tape or caulk that?..not my job..(and people still call that wrap an air barrior?) We need to stag some wall scaffolding to intall that soffit. There's about 50 more 1/8" holes in the air barrior , to go along with the stapple rips and rips the gutter guys put in. Boy, now I'm not too sure it is even a good water barrior now. look at that one , they gift wrapped that window opening with the wrap..now they slapped a window in and nailed it...what they're done? Think about it .. water gets behind siding (above window)..water runs down wrap and behind the top flange of window..oh oh. Reasonable Ralph
*I must admit that I laughed out loud, and a lot when I read Chad challenging Joe Lstiburek's data. I really must ask, who the hell are you Chad? Joe has been doing Building Science research for 30 years. He started the field. Sadly it's still an emerging field that gets doubted by every dime store contractor that has a truck and a hammer.Joe is not alone in his disdain for TYVEK. In fact, nearly everyone in the Building Science field dislikes the product. Anyone that does research on the subject using real-world houses basically doesn't like it.The CMHC has done long term testing and their report uses statements like "no measurable airtightness" in describing the long-term benefits of using the product. Readers looking for more information may obtain this report “Air Tightness Tests on Components Used to Join Different or Similar Materials of the Building Envelope” by contacting The Canadian Housing Information Centre, Canada Mortgage and Housing Corporation, 700 Montreal Road, Ottawa, Ontario Canada, K1A 0P7. Phone 613.748.2367, Fax 613.748.2098.I'll ask you guys that staunchly defend the product a question. How much smaller do you make the furnaces in these houses where you are using TYVEK? If the product has these benefits, why not take advantage of them. It seems from the advertisements for TYVEK that you could wrap it around a corncrib and then live in it! It’s mere presence on the wall insures comfort and efficiency.The software that we currently use do model energy usage on houses doesn’t care whether you have TYVEK on the wall or not.Jon Straube, a researcher out of Canada, is a proponent for taping the seams on the OSB, and then fastening whatever you’d like to use as a drainage plane over it.I’d also like to say that Blue-Eyed Devil is flat out wrong with this “house has to breathe” crap. The key is to make a house tight and ventilate right. Houses that are loose get their ventilation by letting hot air and moisture into roof and wall cavities where it condenses and causes mold and damage – like he mentioned. It also lets in cold air in heating climates that then gets dried out by the heating equipment and causes people to blame forced hot air furnaces for their dry house. Building a house as tight as can be and then providing a controlled amount of mechanical ventilation meets both requirements – durability and fresh air. Not using mechanical ventilation also means that in the spring and fall the house will breathe almost none because there is not enough temperature differential to cause stack effect.The problem he mentioned with the mold inside the walls is because the poly dramatically reduces the ability of the wall to dry to the inside. So when the moisture source is from the outside, which it sometimes is, the poly causes problems. This is why people in building science also don’t like vapor barriers in many instances.I find it interesting that the defenders of TYVEK are probably also completely missing the boat on airtightness. I routinely see so many holes from chases, recessed lights, electric boxes, wiring holes, that it wouldn’t matter if you used window screen to wrap the house.I would encourage all of you to get yourself educated on the subject of Building Science. You owe it to yourself to stay educated and to understand why materials behave the way they do. Buying products based on advertising claims and conventional wisdom is causing you to build sub-optimal houses. I would also encourage you to start doing blower door testing and diagnostics to see where the air is going and to measure whether or not you got any benefit for the money you laid out for a particular product.If you do get educated, the housing stock is better for it. If you don't it just means more work for myself and others that occupy our day fixing the houses you build. Unfortunately doing it right the first time costs almost no more money. After the fact, it's a different matter entirely!For every tight-house failure you hear of, there are dozens of others that have no problems because the whole package was addressed. The ramifications of controlling air leakage impact the moisture load on the building. Tight houses that failed didn’t address moisture loading.Enough for now-Rob
*Houses usually need a water resitant skin under the exterior finish. Tyvek is inferior to felt in this application. Tyvek makes a great jumpsuit for protection from harmfull dust and fibers. That is were i'll use tyvek. Seems that over the last couple of years few regular posters have admitted to using tyvek under siding.joe d
*I think that not nearly enough attention is addressed to air quality in new construction. At my father's school, they got a new building a few years back. The first year they were in the building, they routinely had 30+ students a day go home because they felt ill breathing the fumes of outgassing from glue, paint, and so on. You guys tend to assume that every reputable builder will do things the "right" way - but that's not necessarily true. Fortunately, the outgassing stopped after about a year.
*House too tight? I think AJ once said, "that's what windows are for." OK so I wasted my money on Tyvek. But it makes everyone think I'm building a great house. They'd have thought I was a total nut if I'd used felt on it!! I'm 44 and have lived in this area all of my life and I have NEVER seen anyone use felt as a housewrap. Is poking the same holes in the tar paper somehow better?
*Totally off the wall, but I buy those throwaway 'paper' painters overalls joe, to spray furniture polish, and the bleedin' things are always, I mean always, made with 'Tyvek' branded all over them. Does anybody think I need a non breathing fuggin' house wrap crap white suit here in Houston to spray that stuff when it's 95°F and 80% humidity? I become the 'waterfall' and just drip until my boots fill up with sweat!! I haven't got a bleedin' clue if the stuff is any good in house construction, and frankly, I couldn't care less, but I do know I'm a wee bit more than warm whilst I'm spraying polish!! ;-) Sliante, RJ.
*Did you know........ that the milk container you recycle today could be wrapping your house next week?Or how about that "business card" you guys used to hand out to the girls that said "If you don't want to sleep with me, just tear up this card".http://www.tyvek.com/
*I believe the housewrap and the coveralls have the same brand name, but are actually made differently. The coveralls DO NOT breath for sure.
*Joe, tell your guy that insulation does not stop air infiltration. Air will blow through insulation. You have to keep the air from blowing at insulation, then it can do it's job retaining heat (or cold).blue
*Let's just keep it simple. Air won't blow through a wall if it can't go through the inside vapor barrier. Water won't get in if you shingle with tarpaper. Do each thing well with it's specific purpose in mind. The KISS method to a happy home.
*arcwood - I am afraid you are confused as to the purpose of the vapor barrier, or vapor diffusion retarder. I assume you are referring to poly. This is to supposedly stop moisture migration by diffusion through the drywall. The air barrier is supposed to keep inside air in and outside air out.Vapor barriers have dubious benefits and as a result alot of us don't recommend using them.The problem with typical installations of vapor barriers or air barriers is that they are not continuous, so moisture transport by convection short circuits both of them.-RobP.S. -I just saw a guy flashing his concrete porches to the wood framing with TYVEK, anyone care to argue the "benefits" of this approach?
*Wouldn't think there'd be any benefit as the water if it gets behind the concrete may be in prolonged contact with the flashing and will surely go through the Tyvek which is not advertised or inteneded to be "waterproof".THE advertised benefit of Tyvek is that it keeps water/wind from blowing in from the outside, yet allows the interior to breath to the outside. It should actually help with sick house syndrome -- it is not meant to make the house airtight.
*Rob, what do you mean by "flashing his concrete" to the wood framing?Forget that. I have a more pressing question.I saw a guy putting the Tyvek onto the studs, then sheathing over it with osb. Osb has that coated underside that is water resistant. Wouldn't the backside of the osb and the face side of the tybvek trap mositure and cause mildew?We are in a cold climate.blue
*If Mr. Lstiburek's point is about tyvek versus better air sealing/insulation methods, and I think it is, then he has a valid conclusion: tyvek didn't make a difference but his other methods did. However if the purpose was to compare tyvek to building paper, Chad has a point. To make this comparison, you need to make identical houses differing only in one thing: tyvek vs. building paper. That way, the experimental group and the control group are the same except for one factor. This is simple science, whether building science, physics, or chemistry. If you don't compare apples to apples, you can't make accurate conclusions. Dan
*dan... houses don't make good labs... they don't have controlled invionments.. and no two are built the same.. how would you write the spec so the only difference is that one is built using tyvek.. and one with felt...... i don't think it would happen... and..you would have to occuppy both houses with robots.. because people inhabiting them would completely invalidate the experiment...sounds like some of the HUD experiments with solar in the '70's ..almost zero useful data....most of the data that is useful today from that era came from the fringe....
*Thanks Mike.I agree houses don't make good labs, and they'd be expensive labs. The results also take a long time to discover, and it can be hard to quantify the causes of failures. However, to some degree, you can characterize some of the variables for houses in a given neighborhood through statistics with a large enough sample size to average out some of the factors such as # people living there, weather exposure, average temperature that occupants like, etc. At some point I think you can draw reasonable conclusions, even if it isn't exact. However, the experiment would have to go on for a lot of years before you conclude anything. Perhaps both would be good initially, but what happens if the housewrap/paper reacts with the siding? When does that occur, on average, and what happens to performance after that? Lots of questions would remain unanswered.Dan
*To clarify, I agree with Mr. Lstiburek's: there are better ways to get a bigger bang for the buck than tyvek.
*Come on guys, Tyvek isn't that expensive. I just did a 1070 sq ft home with 2 rolls, grand total = $290 CDN. Most people cheap out on their paint and save more than using felt.Tyvek does breath, I think it breathes more than felt. But that's just my opinion. Both will keep the weather out, both will (or should) inhibit rot. It's obviously proven that most leakage in a home comes from other improper sealing techniques: HVAC, plumbing, electrical. But in the meantime, I won't stop using an exterior wrap that I think is superior. If I didn't care about the product I sealed the house with, I would use nothing at all.
*The experiments you describe - existing houses, lots of houses, known number of occupants, etc. Are precisely what Joe does and is doing right now. Centex and Pulte homes (among others) are building houses to his specs and they are measuring their results.I suppose I don't dare say what they are looking for specifically lest it all be called Bull Sh*t.-Rob
*C'mon, Rob. All we're saying is you either compare apples to apples, or don't act like you did. I'm sure Joe L. is a man of integrity and has done lots of good work and drawn lots of valid conclusions. But science is not guesswork. From what I read, sounds like he has an axe to grind with Tyvek. When someone writes an article for publication, it needs to be fair and objective; otherwise, it's an opinion column and needs to labeled as such.The fundamental problem with a lot of the research that's done is an hypothesis is put forth, and then data is collected to prove - or disprove - it. The way the research is done is usually influenced by the initial assumptions or point of view of the researcher, and thus the results or conclusions are often skewed. If Joe L. doesn't like Tyvek, then his research will disprove it's usefulness. If I like it, mine will say it's just wonderful. That's not science. That's politics.It would be extremely easy to build identical houses --it's done every day in developments all over the country, same floor plans, same specs, often just not on the same street. Do all the air sealing stuff on both, just cover one with Tyvek ("properly" installed -- no cheating or shortcuts) and one with felt. And let the dispassionate data determine the results.
*Crusty - I agree, but the problem is withthe term "properly." If everything were properly done, nothing would ever go wrong!If no one installs it properly, yet they think they are benefitting, is this a good thing?-Rob
*"If no one installs it properly, yet they think they are benefitting, is this a good thing?"....hmmmWell, if they think they've benefited, and they feel they've used a "quality" product -- and feel good about it -- and they can afford it..... I guess it would be a good thing. If Tyvek makes the homeowner happy, who are we to question its use?
*I think you hit on an age old topic - consumer education. I know on this site we've all bitched about that.Perceived quality is the argument that is tough to argue. The consumer thinks your being cheap if you don't use it.I question it's use because I get calls to fix houses that have problems it was supposed to fix!-Rob
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The July 2001 issue (#140) has a response by a DuPont representative to the FHB #137 article about housewraps and a subsequent response by Mr. Lstiburek. The DuPont rep is absolutely correct and Mr. Lstiburek is wrong. If Mr. L were to compare apples to apples he may have a valid argument about housewraps; but he is not making equal comparisons (haven't you figured that out?)! Of course his homes are going to have less infiltration if he seals around bath tubs and fireplaces; installs draft stops; installs taped rigid insulation and moves ductwork to the building core.
I would ask Mr. L to do the same with 200 houses; 100 using Tyvek and 100 using kraft paper or felts. I would be willing to put money on the Tyvek houses having lower infiltration. I'm shocked that the FHB staff hasn't exposed the flaw in Mr. L's argument.
Chad Sutter
Miles City, Montana