New Tyvek over old Tyvek? - Contractor Talk - Professional Construction and Remodeling Forum

Jer · 12-31-2008, 09:23 PM

Heres hoping there are some old siding pros out there.
Two and a half years ago I framed up my shop which is thirty feet by forty five with a loft above that might at some point be turned into a mother-in-law apartment or such.
I finished the framing and roofing and tyvek housewrap but thanks to some uncollectible accounts and a rotator cuff surgery I ran out of money before I could put on siding.
I am now ready to install the siding which will be fiber-cement lap siding and my question is this. Can I put new Tyvek house wrap over the old tyvek which has weathered some and is ripped up in a few spots from wind damage. Would there be any sweating issues created by a double layer of tyvek?
Also I would appreciate any advice on brands of fiber cement...I can get a better price from my supplier if I use Certainteed rather than Hardi.
Any input will be much appreciated.

MALCO.New.York · 12-31-2008, 09:25 PM

Double "Barriers" are ALWAYS BAD.

Creates a "Moisture Trap".

And where there is uncirculated Moisture, there exists Mold or Saprophytic growth.

Burby · 12-31-2008, 10:10 PM

Malco is correct, best to strip the old tyvek off & start new. Tyvek begins to fail in weeks if left exposed, I believe it is 30 days max if left exposed to the elements.

Why not use 30 lb felt? It has a better perm rating & so much easier to work with.
I have no preference between hardi or certinteed. I began using hardi siding in 92 or 93 I believe. And have since with exception of one house.
I just used more hardi because of availibility is all.
Great stuff especially when working alone.
Torn rotator cuff sux huh?
Good luck with your project

mics_54 · 12-31-2008, 10:59 PM

Layering tyvek probably won't cause any adverse conditions of any type. Tyvek is not a vapor barrier (not that it matters) Its only purpose is to repel water which finds its way under the siding and to reduce wind infiltration on crappily constructed frame structures. Its not likely to cause condensation since its permiable. That said it's easier to take it off now than after you put your siding up. If you are going to lose sleep over it take it off and do it over.

SLSTech · 01-01-2009, 12:18 AM

MICS54 is correct as long as it is Tyvek Housewrap, not the cheap knock off clones seen @ Blowes & elsewhere which is simply perforated plastic. If it is one of those knock offs, MALCO & Burby are correct. FYI - while Tyvek should be sheathed over ASAP, it is spec'd out to a 120 days as long as any tears, rips, etc... have been fixed. personally I would redo it - but that is just my style

As for the Fiber Cement, it is simply up to you. Look at their specs, compared to what you want & need then make your choice. They are both well respected companies that turn out good products IMHO.

Jer · 01-05-2009, 12:00 AM

Thanks to all for the feedback on my tyvek question. I was hoping it would be safe to leave the old layer on because it would save a lot of hassel and dumpster space, but it sounds like most of you would be leary of a double layer. Better safe than sorry I guess.
In browsing some past posts on this site I ran across one that said ring shank nails should not be used on fiber cement siding because it could blow a hole on the inside of the panel. Have any of you heard this before?
Thanks again for all your help.

MALCO.New.York · 01-05-2009, 12:05 AM

Quote:

Originally Posted by Jer

In browsing some past posts on this site I ran across one that said ring shank nails should not be used on fiber cement siding because it could blow a hole on the inside of the panel. Have any of you heard this before?
Thanks again for all your help.

New Thread at hand here?????

Why Yes!!!! Please do so.

tomstruble · 01-05-2009, 12:09 AM

call dupont see what they say

Burby · 01-05-2009, 05:23 AM

[quote=Jer;571038]Thanks to all for the feedback on my tyvek question. I was hoping it would be safe to leave the old layer on because it would save a lot of hassel and dumpster space, but it sounds like most of you would be leary of a double layer. Better safe than sorry I guess. [quote=Jer;571038]

Jer, here is the tyvek FAG page link as well as I did send an email to Tyvek & you can leave it on, Tyvek is a breathable wrap & it won;t hurt to leave the old, for the purpose of tyvek you do need a new layer for it's intended protection.
I do stand corrected on time of exposure, it is 120 days as one stated above.
I personally do not believe in build up of anything, (personal opinion, because of my work discoveries & mold as well as on tyvek in some remodels where siding removal finding mold on the outside of tyvek, (may not be related to the tyvek at all, but was there enough times)
Tyvek is their product & Dupont has an excellent rept leaving me no reason to doubt them.
Since late 80's I have used only 30 lb felt, except once, after reading the studies done by the different Universities Tyvek vs 30 lb felt. A house i first built here w/brick veneer, called for tyvek, no similar products to be applied. While waiting for the brick Contractor I was concerned about exposure, I contacted my Salesman & was informed breakdown begins after 2 weeks, fails after 30 days. I do apologize for any delays or confusion.
Here is the link to Dupont Tyvek FAG page

Click here: Frequently Asked Questions

MALCO.New.York · 01-05-2009, 02:58 PM

If they say it is a go....................Then it is.

I would like to see an actual study done.

I have on many an occasion worn TYVEC White Suits. They DO NOT breath so well.

That is the reason that Forensic Investigators wear them a Crime Scenes. To PREVENT contamination by themselves of the Scene.

Hell! They PREVENT the passage of Blood Born Pathogens. Could not be too well breathing like that!!

http://images.google.com/imgres?imgu...%3Den%26sa%3DG

http://www.gullstop.co.uk/content/Gu...%20website.bmp

Jer · 01-05-2009, 11:27 PM

Many thanks Burby. This morning I asked my siding supplier to talk to his tyvek rep about it but I havent heard back yet.

mics_54 · 01-05-2009, 11:30 PM

tyvek house wrap suits????
dupont manufactures alot of different tyvek materials for different levels of permiability and applications. Tyvek housewrap isnot used as hazard suits.

thesidingpro · 01-06-2009, 08:09 AM

You're right. They don't make it out of the exact tyvek housewrap but it's similar.

http://www.disposable-garments.com/biohazard_suits.html

mics_54 · 01-06-2009, 11:08 AM

perm ratings of the house wrap and hazard suits are not similar, which is the point. House wrap lets water vapor out while repelling water liquid and reducing wind penetration. Hazard suits are relatively impermiable compared to house wrap.

MALCO.New.York · 01-07-2009, 06:15 AM

Thanks for the Education!

Burby · 01-07-2009, 06:24 AM

Don;t wait for your salesman, they prolly give you the wrong info as well. haha
Sometimes anyhow..
Here is the email I rec'ld from tyvek when I asked if the exposure time had changed over the years. Back in early 90's when we ended up in a delay with the brick guys, I asked the exposure time to my salesman to know how long we had while waiting.
He said 30 days before needing replacing.

Reply from Tyvek:

You are welcome Fred. The UV exposure time of Tyvek® has always been 120
days. The salesman you spoke with provided you with incorrect information.
Regardless if the Tyvek® was installed in Alaska or Florida, the UV
exposure time has always been 120 days for our residential products - 270
days for our commercial products introduced in 1998.

Always a pleasure,

T. Louise Pope-Womack
Tyvek® Weatherization System Products
Technical Network Support
1-800-448-9835 (prompt 1)
www.tyvek.com
Other DuPont products www.dupont.com

MALCO.New.York · 01-07-2009, 07:33 AM

Take a 12x12 Square of Tyvek. Suspend the corners. Poor water on it. Will it seep or even weep or sweat??????????

I DO NOT know.

But I bet it will not!

critter · 01-07-2009, 08:41 AM

An EXPERIMENT??? There ya go, Malco, thinkin' like a techie! He he!

MALCO.New.York · 01-07-2009, 08:43 AM

Empirical Data is ALWAYS "On-Point"!

mics_54 · 01-07-2009, 09:56 AM

Quote:

Take a 12x12 Square of Tyvek. Suspend the corners. Poor water on it. Will it seep or even weep or sweat

what type of tyvek? Tyvek house wrap will seep water from the back to the front...less so in the other direction. But that's irrelevent to the fact that the tyvek house wrap is made to allow vapor to pass through while inhibiting liquid which is what has been stated several times. House wrap is engineered to prevent water from entering the wall space from the exterior while allowing water VAPOR to escape to the exterior. Tyvek house wrap requires installation with the printed side toward the exterior for it to function as designed. House wrap and chemical or bio hazard suits are made from a different type of tyvek with a different permiability. You can read about it on their web site.