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Tyvek

Rider Rick

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Oct 19, 2009
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Have you ever seen Tyvek used on the inside of exterior walls?
 
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cda

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Should DuPont Tyvek® HomeWrap® be placed over or under the sheathing?

DuPont Tyvek® HomeWrap® can be used either over or under sheathing. When DuPont Tyvek® HomeWrap® is used under sheathing, it functions only as an air barrier and does not protect the sheathing as a secondary water barrier. DuPont Tyvek® HomeWrap® has been used directly over studs where there is no sheathing, although use of sheathing is a highly recommended building practice.

https://www.diyhomecenter.com/dupont/tyvek/faq.aspx

use a Tyvek® weather barrier in combination with a vapor barrier?

Using a Tyvek® weather barrier in combination with a vapor barrier depends on how the rest of the wall system is constructed, and the climate the building is in. If the majority of the year is spent heating the home, where the inside temperature is greater than the outside, it is generally good to use a vapor retarder behind the interior drywall. In hot, humid climates, vapor barriers should not be used.

http://www.dupont.com/products-and-services/construction-materials/building-envelope-systems/faqs/wb-faq.html
 
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conarb

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In my estimation this has been the biggest failure or both contractors and building inspectors in cases I've been involved in, I'm glad to see that DuPont is finally making it clear that Tyvek is not a WRB.

The history is that DuPont tried and failed to get Tyvek approved as a WRB because it could not pass the "Boat Test" (or "water holdout test"), in what I consider an unethical move they got the ICBO to approve it as an air barrier and not a WRB (there was no air barrier requirement in the code), many CBOs approved it under the alternative materials and methods section of the code, I advised a few over 20 years ago that they were crazy and should be held accountable, the ICBO Report on the material clearly stated that ti was approved as an air barrier and not a water barrier. Eventually DuPont changed course and attacked the boat test and got the ASTM to approve a new test, the 'Hydrostatic pressure Test", a test with different parameters that Tyvek could pass, so for several years we had two tests for a WRB, the boat test and the hydrostatic pressure test. When the ICC took over from the ICBO (and other code writing agencies) the old approvals were supposedly retained as "Legacy Reports", at some point I went to the Legacy Reports to copy the original Tyvek approval and it had disappeared, I contacted the ICC and they disclaimed any knowledge of what had happened with some kind of weak excuse about all they were doing was republishing the ICBO reports as Legacy Reports.
 

Mark K

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May 12, 2010
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My understanding is that in some climates it makes sense to put the membrane on the inside, but you need to know what you are doing. You need to be talking to somebody who is an expert in building science.

Forget the evaluation reports. What does the building code say about these membranes and whether the products comply with the code requirements. One must keep in mind that ICC_ES takes money from manufacturers to product these reports and ICC-ES does not independently perform any tests.
 

conarb

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I haven't looked it up in years so I just did:

\ said:
R703.2 Water-resistive barrier. One layer of No. 15 asphaltfelt, free from holes and breaks, complying with ASTM D

226 for Type 1 felt or other approved water-resistive barrier

shall be applied over studs or sheathing of all exterior walls.

Such felt or material shall be applied horizontally, with the

upper layer lapped over the lower layer not less than 2 inches

(51 mm). Where joints occur, felt shall be lapped not less

than 6 inches (152 mm). The felt or other approved material

shall be continuous to the top of walls and terminated at penetrations

and building appendages in a manner to meet the

requirements of the exterior wall envelope as described in

Section R703.1.

Exception: Omission of the water-resistive barrier is permitted

in the following situations:

1. In detached accessory buildings.

2. Under exterior wall finish materials as permitted in

Table R703.4.

3. Under paperbacked stucco lath when the paper

backing is an approved water-resistive barrier.
I am very surprised to see a change here from the last code I looked it up under, in the past there was also an exception allowing for an approved alternative, in the past CBO's who allowed Tyvek did it under the approved alternative exception and as far as I have ever seen required documentation in the form of an ICBO or ICC Report. In the 2013 Code I see no exception allowing Tyvek or any other plastic wrap at all. In the past allowing it was misfeasance, allowing it now is malfeasance.
 

msmrphy

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Feb 1, 2016
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Location
Houston, TX
My $0.02

Conarb, you might also want to mention that special conditions apply if the finish is stucco and the sheathing is plywood. My understanding is that plywood substrates require (2) WRB's under stucco. I've seen too many failures in poorly applied stucco systems that used a house-wrap only, without a backer paper. You're simply inviting a soggy plywood sheet, and where I live that means termite infestation. Perhaps I'm old school, but 15 # felts still do it for me as a WRB. Air barriers are a different animal, of course, and permeance is key when deciding where to place it in the wall assembly. My $0.02
 

conarb

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There is strange language in the code stating that the WRB can be omitted: . 3) Under paperbacked stucco lath when the paper, Paperbacked stucco lath is two layers of Grade D paper so it is an approved water-resistive barrier. Because of the problem you reference I go to great lengths and expense to eliminate the plywood sheathing, including getting the engineer to approve putting the diaphragm plywood on the interior rather than the exterior and it some cases installing a full steel frame. The last home I built I installed a full steel frame because in our seismic zone the engineers require so much steel that it really isn't a larger expense. In a prior house I had $30,000 worth of Simpson metal which probably cost me $60,000 to install and there were still $30,000 worth of steel moment frames, on the last house I did a full steel framed for $120,000 with probably $10,000 worth of Simpson and labor. Most affluent owners will pay the extra cost to get a better building. I then use old fashioned line-wire and 4 coat stucco so there is no sheathing to rot out and seal up the walls.

The fact is that walls have to breathe to dry out from the inevitable moisture that is eventually going to get in, plywood seals the exterior and sheetrock seals the interior, if you use plywood sheathing you are creating a dual barrier sealing moisture in. In the old days before plywood we used 1x8 boards for sheathing, and that is still in the prescriptive code, we used low grade 1x8 full of knots and green, when the knots fell out and the boards dried out there was plenty of room for the moisture to dry out the exterior.
 

conarb

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Diagonal board sheathing is a prescriptive bracing method as well.
You know I considered that on a house but the mills, at least here in California, don't mill it any more, my yard offered to run 2x8s through their resaw machine to make them for me. Too bad, we actually wanted very low quality material so plenty of air could flow through it. Back in the 40s and 50s the first thing I did when starting a house was ordering units of 16' 2x4s and 16' 1x8s, we used the 2x4s for walers and the 1x8s to line the forms, after we stripped we had a laborer clean them up so we could reuse the 2x4s in the framing and the 1x8s as diagonal subfloor and wall sheathing if we were building a stucco house, we never sheathed a house getting redwood siding so the redwood could breathe, by the mid 50s we eliminated wall sheathing altogether and used line-wire behind stucco so it could breathe
 

ICE

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California concrete jungle
Have you ever seen Tyvek used on the inside of exterior walls?
I have seen Tyvek end up in a pile on the top of the bottom plate. There is another product called Barricade that is much more durable. I don't know if it rots like Tyvek.
 

ADAguy

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Conarb, bet you used button board for interior lath too (smiling). Built my mom's house that way and it road through Sylmar and Northridge fine.
 

Pcinspector1

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MID WEST
I once meet the guy from the Federal Government that said he prescribed polyethylene on the ceiling of government backed loans on residential homes. He was out promoting cellulose blow-in insulation after he'd worked for the Feds.

He said Quote: "Don't do that!"

He kinda looked like Jerry Clower!
 

conarb

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Oct 22, 2009
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My250:

With conventional stucco 3 layers are required, on high quality work we are now doing 4 layers, that ES Report is confusing in that the one report covers several products, my interpretation is that it only applies to EIFS and one-coat stucco, not conventional stucco.
5.0.5.3
When DuPont™ Tyvek® StuccoWrap® –Style 1062X, DuPont™ Tyvek® DrainWrap™–Style 1063X or DuPont™ Tyvek® CommercialWrap® D-Style 1083 are used in an EIFS wall covering assembly with drainage or a one-coat stucco assembly as described in Section 4.4, the assembly must be specifically recognized in the evaluation report on the EIFS or one-coat stucco.
 

my250r11

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Roswell, NM
upload_2016-10-3_16-19-52.png

They have to use the correct style but the report says they comply with type D paper.
Cali. might require more but here just the min. above and beyond is great but don't get it much.
 

conarb

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Oct 22, 2009
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California East Bay Area
View attachment 2409

They have to use the correct style but the report says they comply with type D paper.
Cali. might require more but here just the min. above and beyond is great but don't get it much.
How do you know as a plan checker which "style" complies?

The biggest problem with any plastic WRB is they all disintegrate when in contact with a surfactant, cement,tanins in redwood and cedar are all surfactants. About 30 years ago a Stanford electrical engineering professor asked me to bid his house, he specified Tyvek under redwood siding, I refused to build the house with Tyvek, he insisted on it because fo it's air blocking qualities, the house was on a hill top overlooking the Pacific Ocean on the west and Silicon Valley on the east, the house was/is subject to over 100 MPH winds. A few years ago he called to say that I was right, all the Tyvek had literally disappeared leaving nothing but a few white plastic shards at the bottom of walls, he had ripped the redwood off a couple of leaking walls. He wanted me to replace the redwood with Grace's new liquid Therm-A-Barrier and the Hardie Artisan siding, again I refused. You can go to Building Science Corp's site and find all kinds of information on Tyvek and tannins.

Tiger:
Tiger said:
Please enlighten me on steps, materials and methods that you employ to avoid cracks in stucco plaster.

I do not sheathe behind stucco, if I have to I use diagonal 1x8 but prefer to get the engineer's approval of interior sheathing, or brace with a steel frame. The best way to explain is a picture fo one of my walls, house braced with a steel frame, two-layers of Grade D over line-wire, one scratch coat of stucco, one brown coat of stucco, two color coats of line-wire.jpg stucco.
 
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