# Tyvek behind vinyl siding



## HankMaine (Apr 23, 2012)

I have a 43 year old home and I'm having HD install new vinyl siding. My task is to remove the old cedar siding but one thing my sales person told me has me concerned. He said I can remove everything down to the wood including the old Tyvek because the 3/8" insulation board and the Crane Market Square siding will be all the weatherization I need. So, should I leave the old Tyvek on (now full of nail holes), pull it off and replace it or trust that the insulation board and crane siding will be good?

On another note, HD replaced all my windows last month and one issue they found was that the flashing over the windows had been nailed down so they could not get aluminum wrap under flashing, instead they went over the flashing and then applied calk. I asked my sales guy if maybe we should put new flashing over windows when we do siding and he said the J channel installed around the window would keep water out. He also said they could put a bead of calk between the J channel and aluminum window wrap just to be safe. I've read lots of conflicting info on the best practice. Any advice?


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## tinner666 (Mar 14, 2005)

Caulk doesn't last very long. http://www.albertsroofing.com/Window Flashing.htm


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## Tom Struble (Dec 29, 2008)

:no:i would be leery of this salesmans advice


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## joecaption (Nov 30, 2011)

If windows and siding are installed correctly there is no caulking even needed.
Window tape, and Z molding over the widow should be keeping the water out.
Caulking can even act as a dam and keep water in when it cracks to let water in.


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## woodworkbykirk (Sep 25, 2011)

new windows and new siding always means install new flashing. its the only way to guarentee a leak free install.. j channel does not keep water out its simply a trim for the siding to tuck into. 

vinyl siding is not water proof by anymeans. a house thats getting new siding should be 100% water proof before any siding goes on in the first place.. the siding itself just adds another layer of defense and makes it look good


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## jklingel (Dec 21, 2008)

new house wrap and a rain screen. it never hurts to keep liquid water away from your walls.


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## HankMaine (Apr 23, 2012)

Thanks all. After I install the new Tyvek should I tape around top / sides of windows with Tyvek tape or is there another product which is recommend ? I've seen people use what looks like Grace ice / water shield before but I wonder if that's overkill?


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## jklingel (Dec 21, 2008)

that is a vapor barrier (serious retarder) and should only be used under special circumstances.


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## Tom Struble (Dec 29, 2008)

i think he's talking about flashing tape which is different from Tyvek tape and may or may not be needed in the op's situation


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## woodworkbykirk (Sep 25, 2011)

blueskin, vycor, along with 3m flex flash are various types of the flashing tape. they perform far better than standard red tucktape which the glue on loses its tack after a few years. from what i understand tuck tape has been banned in alberta for rain screen applications as too many installers are relying on it too much


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## jklingel (Dec 21, 2008)

oh, if tape, it matters not about it being vapor proof. i thought he was talking about applying the ice shield over the whole wall. there are tapes made specifically for each of the rain-repelling products. yes, regular duct tape is a very poor choice.


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## HankMaine (Apr 23, 2012)

Man, it's amazing how many opinions there are about the Tyvek / Fan Fold Insulation combo under Vinyl. I actually found a post on the Pro chat room from 2009 which had me all confused :laughing: 

My plan is new Tyvek with Tyvek tape on vert seams only, then the 3/8" fan fold over it. The windows are still up in the air a bit. I'll grab some detailed pics tonight and see what you all think. I'm in Maine and I live on top of pretty big hill so rain / snow with heavy wind is all too common. I better get this right the first time because I'm mortgaging the farm for this project


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## woodworkbykirk (Sep 25, 2011)

hank, im not that far from your location and its pretty much industry standard now to use peel and stick membrane for flashing windows and going "captain overkill " on it includes putting a aluminum cap flashing over the top of the window. 

very few guys are using red tape alone anymore and those who are.. arent getting much work after the fact... as for fan fold and tyvek. if you do use both only tape the tyvek


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## HankMaine (Apr 23, 2012)

OK, here is the deal.

I plan to wrap house in Tyvek, tape vert seams with Tyvek tape then they will apply fan fold over top (no tape).

I'm worried about windows...

The picture (postnew) shows post window install by HD. They could not get the wrap under the flashing on top due to the way it was nailed down / existing siding so the calked it. They got the aluminum wrap over the old trim as close as they could on the sides.

sidingoff shows what I found when I started pulling off cedar to deal with 20 year old leak.

If I install a new flashing over the top of old flashing and existing wrap (behind tyvek) should I add some blueskin or similar flashing tape product too? 

My big question and worry is the sides.. what do I do there? HD would say 'calk it' 

Thanks all!


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## Tom Struble (Dec 29, 2008)

hmm.. yea..i would redo the aluminum trim and return it back onto the wall

but you could use L shaped aluminum slide it under the 3/4 return on the side and the other leg of the L on the wall

the most important parts imo are the sill and head flashing

you need to have a separate Z shape head flashing,don't just j the head the way it is now


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## troubleseeker (Sep 25, 2006)

HankMaine said:


> I have a 43 year old home and I'm having HD install new vinyl siding. My task is to remove the old cedar siding but one thing my sales person told me has me concerned. He said I can remove everything down to the wood including the old Tyvek because the 3/8" insulation board and the Crane Market Square siding will be all the weatherization I need. So, should I leave the old Tyvek on (now full of nail holes), pull it off and replace it or trust that the insulation board and crane siding will be good?
> 
> On another note, HD replaced all my windows last month and one issue they found was that the flashing over the windows had been nailed down so they could not get aluminum wrap under flashing, instead they went over the flashing and then applied calk. I asked my sales guy if maybe we should put new flashing over windows when we do siding and he said the J channel installed around the window would keep water out. He also said they could put a bead of calk between the J channel and aluminum window wrap just to be safe. I've read lots of conflicting info on the best practice. Any advice?


While some types of insulation board may very well serve as a vapor barrier, depending on the face material, it is completely dependent on the proper sealing of all joints and surface damage to accomplish this. Also, depending on the specific material of the insulation board, it may absorb moisture itself. You don't want to create a moisture trap, so if the insulation board is being touted as a vapor barrier, I would not put Tyvec on top of it; but would use felt, which is much more permeable. No matter the product, the substrate of the house must be completely waterproofed before the siding is installed, and the window and door heads properly flashed..not caulked. 
Look at any manufacturers installation guide online and you will notice that one of the first requirements for them all requires that the building envelope be weather tight, as vinyl siding is not a waterproof cladding. Any salesman or installer who tells you that is either incompetent in his job or plain lying.


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## Tom Struble (Dec 29, 2008)

felt has a lower dry perm rating than tyvek

and whether the foam is on top of the wrb or under it is not going to affect the foam perm,but it will affect the wrb perm


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## jklingel (Dec 21, 2008)

but remember that felt has a perm rating of about 5 when dry, but something like 50 if it gets wet. i would not use it over foam because it would be difficult to adhere it properly. tyvek over rigid foam is very common.


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## Gary in WA (Mar 11, 2009)

I'm giving you the "whole 9 yards" as I don't your experience: WRB; http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_7_sec003_par003.htm

Flashing: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_7_sec003_par035.htm

Header flashing, required in Canada, as Kirk said; http://joneakes.com/jons-fixit-database/2062

Paper: http://www.buildingscience.com/docu...od-frame-wall/?topic=/doctypes/researchreport

Window pans: http://www.buildingscience.com/docu...penings/files/bscinfo_302_window_flashing.pdf

WRB and windows leak: http://www.buildingscience.com/documents/published-articles/pa-water-managed-wall-systems

Watch the install, document with pictures; http://www.vinylsiding.org/installation/manual/

Closed-cell fan-fold over the "stucco" housewrap for an airspace to the foam; http://www.buildingscience.com/docu...nd-the-gap-eh/?searchterm=foam board in walls

Gary


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## HankMaine (Apr 23, 2012)

Just an update. I went to the Green Guard site and found the installation instructions which specifically say once you have attached it you should tape every vertical and horizontal seam (when used as a water resistant barrier). http://greenguard.pactiv.com/productfiles/product-downloads/installation-guides/greenguard-fanfold-siding-underlayment-wrb-installation-guide.pdf

Since I decided to go with just the fanfold and no Tyvek I asked the contractors installing the siding to do this and they agreed (even though they normally don't tape). Basically what I have learned is that you can go with Tyvek and fanfold in which case you should tape the seams only on the Tyvek. If you decide to go with just the fanfold you should tape fanfold seams.

Thanks for your help everyone.


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## Tom Struble (Dec 29, 2008)

you really didn't just use fanfold for the wrb did you:huh:


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## Gary in WA (Mar 11, 2009)

That brand of fan-fold can be used for the WRB, though consider this:
It appears you are having trouble deciding on the proper course to follow. It can be confusing….. I’ll try to be brief.

1. You are in *Zone #6*, Cities below the map, per State unless in Aroostook- Zone 7: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec001_par001.htm

2. Your Code required insulation value for *“Wood frame wall”* is R-13 + 5h---- read the “h” footnote: http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

3. As you have solid wood sheathing rather than structural panel sheathing on this older house, minimum Code (like a “D’ at school) requires R-5, not the R-1----- R-3.6 of your product: http://greenguard.pactiv.com/produc...rd-fanfold-siding-underlayment-data-sheet.pdf Notice also, the *perm ratings of 1.3---1.7perms*, AND the *water-absorption rating of “2”* for all products.

XPS has a perm rating of 1.1 per inch of thickness, 2” = *0.70 perm*, about the same as plywood: http://commercial.owenscorning.com/assets/0/144/172/174/e45fe07d-5cc9-4e4b-866a-5e35d75090ec.pdf 
Did you notice the charts at figs.8, 9; showing with R-3 (similar to your “Greenguard”) the sheathing/cavity will be at “dew-point” 42% of the year, but upping to R-10 (2”) will reduce that percentage to zero? 

2x4 walls = *R-7.5*, follow link (Are dew-point calcs. really ness.?) at page bottom if really into this; http://www.greenbuildingadvisor.com...lating-minimum-thickness-rigid-foam-sheathing

In Fig.1 and 2, PUR (faced), moisture pick-up of 2.5 (yours is 2.0) while EXP is 0.9; retains 85% of R-value- XPS= 98%, figure yours……of course that is below ground; http://msdssearch.dow.com/Published...foam/pdfs/noreg/178-00414.pdf&fromPage=GetDoc

4. Just a touch on vapor retarders and lack of, if using exterior insulating sheathing: http://www.rci-online.org/interface/2010-04-gatland.pdf

5. Page #3, *“A”---“C”;* http://www2.dupont.com/Tyvek_Weathe...rior Insulation Building Science Bulletin.pdf

*Briefly*---LOL.
I would use Tyvek “stucco-wrap” for the WRB after furring-out the windows, 2” XPS over that, then vinyl. The f.b. keeps the wall cavity warm, moving the dew-point to the inside of the f.b., ON the outside of the WRB- to drain because the ridges from the product create an air-space: http://www.buildingscience.com/docu...nd-the-gap-eh/?searchterm=foam board in walls

Gary


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## HankMaine (Apr 23, 2012)

So.. in layman's terms .. my decision to go with the 3/8" XPS alone and no Tyvek means .. I'm  

I just spent the past two weeks cutting away and replacing rotted sheathing and studs, I guess in another 30 years (like my father probubly said) it will be someone else's problem :whistling2:


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## kwikfishron (Mar 11, 2010)

HankMaine said:


> So.. in layman's terms .. my decision to go with the 3/8" XPS alone and no Tyvek means .. I'm


Just because it's allowed doesn't mean it's the way to do it. You're putting a lot faith on the tape. 

If I was there I'd be talking you out of the Tyvek too. :yes: But that's just me.


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## Tom Struble (Dec 29, 2008)

how can anybody consider this a weather /water resistant barrier?

hopefully you will get 20 years..i kinda doubt it


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## Tom Struble (Dec 29, 2008)

kwikfishron said:


> Just because it's allowed doesn't mean it's the way to do it. You're putting a lot faith on the tape.
> 
> If I was there I'd be talking you out of the Tyvek too. :yes: But that's just me.



the tape is for air not water,so i have no faith in it:no:


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## kwikfishron (Mar 11, 2010)

Even the Little White Polar Bear looks unsure. :laughing:


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