Tarpaper over tyvek?

John_M · June 04, 2007, 11:35:19 AM

I know this is a strange question but.....

.....last fall I was unable to side my cabin so I wrapped it in Tyvek for the winter. I am getting ready to finally side it (with cedar). I really wanted to use tarpaper but was pretty sure that it would not make it through the winter.

Now that it is wrapped in Tyvek I have 3 options.

1. Just shingle over the tyvek

2. Rip down the tyvek (and those goofy button nails and wrap the cabin in tarpaper)

3. Put tarpaper over the tyvek.

Is #3 an acceptable building practice?? I know normally that would not be done, but in this case, could that cause a problem? Too much protection? (is that bad?) :-?

Just thinking out loud!

Thanks!!

glenn kangiser · June 05, 2007, 12:32:34 AM

I think it would work and protect you from Tyvek problems, but we better wait and see what PEG has to say about it. :-?

June 05, 2007, 08:42:36 AM

Quote

I think it would work and protect you from Tyvek problems, but we better wait and see what PEG has to say about it. :-?

Puttin me on the spot eh

I'm not sure what it [highlight]might[/highlight] do if the Tyvek was really worn out I'd maybe go over it it BUT if it had some life in it , it COULD , set up some wierd situation that COULD be bad.

It will at the very least create lumps which will make line snapping or difficult.

SO it DEPENDS on to many factors I can't see / think of .
G/L PEG

John_M · June 05, 2007, 08:51:56 AM

What types of things COULD :-? happen here PEG?? What do you think the worst case senario would be?

The Tyvek is in great shape. I could just as easily go right over it without the tarpaper and be fairly confident.

PEG688 · June 05, 2007, 08:58:26 AM

A nasty mold build up cause by a dew point between / under the two building papers .

In a high exposeure envir. felt is the way to go when using Cedar. Are you using bevel( lap siding / clapbrds) or shingles ??

June 05, 2007, 09:37:43 AM

We are using cedar bevel siding on the bottom and shingles on the top. Kind of a two-tone look I guess.

I have Tyvek on it now. I don't want to start a tyvek vs tarpaper war again......I just want to do what it right.

I'm sure if I asked 100 people, 50 would say to just leave the Tyvek and 50 would say to use tarpaper instead!

Ugh!! :-/ Decisions..decisions...decisions!!!

Jens · June 06, 2007, 09:55:14 PM

From what I have read, the only approved wrap under cedar is felt paper or Typar. No Tyvek. I don't know about the approval, or who does the approving, but I believe fine homebuilding, (except when they start saying that composite materials are better than real...ok, maybe sometimes) and my choice would be to rip the Tyvek. You could, however, install furring strips over the tyvek, then felt, then siding...probably. Would create venting for the tyvek and sheathing that way. Best idea though, is to call Tyvek. They might know. Get it in writing from them too, so that if your sheathing rots, you can prove what they suggested.

PEG688 · June 06, 2007, 10:37:51 PM

I think Tyvek would tell him "You've left the tyvek exposed for to long ", he wintered it over hence voiding the warrenty anyway. I think they say 60 days is all it's good for if exposed to UV , Typar has a longer UV life IIRC 120 days .

He could strip it out the felt , wouldn't work on the gable ends where he's planning on Wood shingles though , and would create another issue .

Mo · June 07, 2007, 05:29:06 PM

We had condensation problems everywhere the tyvek was left when we replaced it with 30# felt last fall. It was around the windows and doors where it was pulled into the inside as the installation states on the tyvek website. We had to tip the windows and doors and pull out the tyvek and then recaulk. And then replace the felt around each.

June 07, 2007, 08:55:31 PM

Mo,
According to the Dupont website, Tyvek will "allow moisture vapor to escape from inside walls.". Are you sure your "condensation problems" were a result of the felt placed over the Tyvek ? Why was the Tyvek replaced with felt ? Apparently these "problems" occured prior to the exterior siding application, correct ? I'm not sure I understand what you mean by "We had to tip the windows and doors and pull out the tyvek and then recaulk. And then replace the felt around each." It sounds like there may be more issues here than simply the felt having been placed over Tyvek. Considering the perm ratings of 30# felt and Tyvek, in my opinion, the placement of felt over Tyvek should not cause any problems.

glenn kangiser · June 07, 2007, 10:28:35 PM

Tyvek seems to transit vapor but when it condenses to liquid water or gets a leak and rain gets in then the Tyvek will not permit it's passage according to some of the other info we have seen.

Mo · June 08, 2007, 07:43:55 AM

The tyvek was put on over the sheathing, I used the instructions that were out then.
http://www.smithphillips.net/pdf%20files/TyvekhomewrapBeforeInstall.pdf This is the way I did the windows and doors. Then a company that owns the gas well above our cabin, the south facing side, decided to redrill the well, with a huge diesel belcher. It spude crud all over the side of the house and everywhere it hit the tyvek just shredded. So we took down all of the wrap and each and every capnail but since the windows and doors were in I just cut around the flashing and left the tyvek pulled into the windows as you see on the install site and put a strip of rubberized flashing around the edge then put on 30# felt. Then the inevitable happened and My Chef husband decided that my kitchen was to small and before I put on the siding we should add an addition to the south side of the house. I took off the felt and took out the sliding door and windows and at each opening there was mold where the tyvek was wrapped to the inside so I went on to check a couple of the others and it was the same way The water that had gotten behind the tyvek had not escaped in places that were pulled through so I tipped the windows out because it was just me and my daughter and pulled all of the remenants off. I had to recaulk, renail and reflash each of the windows. If you look at the website the flexflashing is over the tyvek, when the water ran down behind it it pulled in the corners and the front of the sill. Sorry it is long but I thought it needed clearing up.

glenn kangiser · June 08, 2007, 07:59:39 AM

Thanks so much for taking the time to post that, Mo. With the advertising budget Tyvek has, most only hear about how good it is. Few hear of the many failures or believe hearsay.

I have heard of entire apartment complexes that had to be torn down in the PNW, due to mold. As you found with oil crud, any surfactant, soap, even dirt can cause failure of the housewrap. If conditions are not right for it, it fails. Builders are not rocket scientist and we are not building rockets. We are building shelter for our families.

Felt is proven by time, and while not the latest technology, it is at least nearly always successful. If there is a failure with felt, you can bet it will be an installation procedure problem, and not because you got it dirty or washed it.

Mo · June 08, 2007, 08:35:20 AM

You are right. One house up here the builder pulled tyvek up under the sill and tacked it to the underside all around the edge. When it was pulled down after a couple of months there was a water puddle and mold all along the bottom. He went back to felt.
I love this sight, I am new to building and doing it myself I first check the manufactures directions or such and then read how it actually works in real life here. It has been a great help. Thanks

glenn kangiser · June 08, 2007, 08:58:46 AM

It is people like you who relay their information and take the time to post it here that makes this site great. Thanks again.