Tyvek vs. Tar Paper

[sourdough]

I'm not much of a carpenter/house builder, but I would appreciate any input.

My neighbor and her husband bought a 1910 farmhouse and have been busy for the past 2 years rehabbing it (new roof, new block foundation, etc.). They are now in the process of replacing the exterior siding (original: cedar shakes; new: fiber-cement lap). They are using tar (roofing) paper instead of Tyvek housewrap because her carpenter-brother says that Tyvek causes mold problems by trapping in moisture behind it.

I'm confused because I was/am under the impression that Tyvek works like Gore-Tex for a house.

Thanks in advance!

Jim

 

[FJ 432]

My understanding is that it is used to prevent humidity from entering the house by creating a barrier. I was told that the side where the logos and writing is the water/moisture barrier and that is why you see that side exposed.

I'm not sure if the other side acts like gore-tex where it allows moisture to leave. The product is expensive but not that expensive.

 

[kj_mustang]

Tyvek lets interior moisture escape.
Tyvek homewrap superior house wrap

 

[tfinniii]

There is also a material you put over tar paper and under shingles,etc. to allow drainage and ventilation.

 

[sourdough]

These folks are installing lap siding directly over the tar paper.

 

[ddawg16]

That question gets asked all the time.

http://www.contractortalk.com/f33/tyvek-vs-felt-paper-better-59073/

And from another site...

Tar Paper vs. Housewrap vs.…
Oooh with so many choices today, just how does one choose the best product? While there will always be some die-hards that will prefer one over the other it all comes down to installing whichever product is used properly. With that, I have to say I am partial to two layers of tar paper behind regular stucco. I prefer a standard Tyvek like product behind foam or under a rain screen / air gap detail. If one can’t use a rain screen detail then I prefer using a HydroGap product.

With that let me finish off by paraphrase one last point from Joseph Lstiburek who states it is up to the designer / architect to use their judgment by weighing the risks, costs, skill of the installers & ones climate. In most cases the weak link is the choices made & the installation process, not the material. Oh ok, I can’t leave this one out – “Just to be clear Duct Tape has 1001 uses, this is not one of them.”

And I find this to be one of the best comparisons..

http://buildingadvisor.com/materials/exteriors/sheathing-wrap/

I think you will find a tendency for contractors to try new stuff....especially the younger guys....hey, who doesn't like high tech.

As with any material, the key factor to good performance is a proper install.

 

[sourdough]

That question gets asked all the time.

http://www.contractortalk.com/f33/tyvek-vs-felt-paper-better-59073/

And from another site...


And I find this to be one of the best comparisons..

http://buildingadvisor.com/materials/exteriors/sheathing-wrap/

I think you will find a tendency for contractors to try new stuff....especially the younger guys....hey, who doesn't like high tech.

As with any material, the key factor to good performance is a proper install.

Great links! Thank you!

 

[WVBrady]

...And I find this to be one of the best comparisons..

http://buildingadvisor.com/materials/exteriors/sheathing-wrap/...

I was quite surprised to read this: "Also, once wet, the permeability asphalt felt actually rises from 5 to as much as 60, further promoting rapid drying. "

This desirable characteristic seems counterintuitive.

The following made me glad that I used the "30 lb" weight instead of the 15:

"However, remember that what is sold as #15 felt today is typically half the weight of traditional 15-lb. rag felt, which weighed – guess what –15 pounds! To get something comparable today you need to buy unrated #30 felt "

How do they get away with that false advertising? Is it the "wet weight"?

 

[rancherbill]

Tyvek is superior on new construction. It is assumed that you have a vapor barrier within the house. In my mind Tyvek is an air barrier that is also a external moisture barrier and will let out small amounts of interior moisture.

On your old house it down not have a modern style barrier on the inside. You really must read the Tyvek site for info relating to your old construction.

 

[jd_1138]

My cousin and I had to tear off the wood siding on one side of my mom's house due to water getting under the wood and warping it. We tore the siding off and were shocked that there was no tar paper or moisture barrier paper under it. Just siding nailed to the framing. And every house on this block has the wavy wood rot damage -- some worse than others.

The contractor probably saved $200 per house and maybe 4 man hours per house by cutting this major corner. A-holes. These houses were built in '81.

 

[Isotope]

I just bought my first garage (w/ attached house ) and was psyched to start setting up shop when I discovered that two walls were completely rotted out. Water had been getting behind the gutters, running behind the vinyl siding and soaking into the tar paper. From what I can tell it was the right stuff, installed correctly, it just wasn't very effective at shedding the water, and became saturated instead.

I had to hold the roof up with temporary walls while I replaced all the studs and sheathing. When I put it back together I used Tyvek Homewrap, not tar paper.

One other note - parts of my house also have a perforated aluminum wrap over the tar paper, I suppose for insulation. This certainly didn't help it dry out either. I just learned DuPont makes this stuff called ThermaWrap that adds R5 insulation to the wrap. I probably would have tried it instead if I knew.

 

[6768rogues]

Tyvek is supposed to let water vapor escape but not let wind or liquid water pass through. Virtually all manufacturers of felt paper say it is for roofing and not sidewall use. The code allows it, but the manufacturers must know something that the code writers don't know.

 

[ddawg16]

Tyvek is supposed to let water vapor escape but not let wind or liquid water pass through. Virtually all manufacturers of felt paper say it is for roofing and not sidewall use. The code allows it, but the manufacturers must know something that the code writers don't know.

Yea....they want to sell you something.

So far, I'm convinced tar paper is better for walls. For the roof, the new synthetic stuff seems to be better.

One advantage of tar paper, the tar seals around nail holes.

 

[DEnd]

I just bought my first garage (w/ attached house ) and was psyched to start setting up shop when I discovered that two walls were completely rotted out. Water had been getting behind the gutters, running behind the vinyl siding and soaking into the tar paper. From what I can tell it was the right stuff, installed correctly, it just wasn't very effective at shedding the water, and became saturated instead.

To be fair any of the building materials would have likely done that. The WRB (Weather Resistive Barrier) is not designed to handle large amounts of bulk water. The large leak that you had was probably close or worse than basically not having any siding on the house. Given proper installation of flashing details, and WRB either felt or Tyvek will work well. If the flashing details and/or the WRB is installed wrong then neither will work well.

 

[slackdaddy1]

Tyvek deteriorates rapidly when in contact with tannin acids in some woods like cedar.
Tyvek is definitely not a good idea behind cedar.
Also, you really need a rain screen/drainage plane between the sheathing and wood siding. 2 layers of "tar paper" provide this.

Slack

 

[Falcon67]

Yea....they want to sell you something.

So far, I'm convinced tar paper is better for walls. For the roof, the new synthetic stuff seems to be better.

One advantage of tar paper, the tar seals around nail holes.

My dad and grand dad both used tar paper on buildings - out buildings, house remodel, etc. I think it outlasts Tyvek is a lot of places. I used some on the shop build, only around the base. Used the synthetic stuff on the roof, recommended. Ran out before the last pass across the peak so I finished with some 30 lb felt on top. We had a windstorm - of course - before I got shingles up and the 30 lb went all over the neighborhood.

 

[justinjoyal]

I have never seen anythig other than Tyvek or Isoclad used outside new constructions. It’s designed to let moisture out but to be air/liquids tight.

It’s cheap and effective..

Also did I get it right? They’re installing the siding directly over the paper, no air gap?!

 

[Lelandwelds]

I have never seen anythig other than Tyvek or Isoclad used outside new constructions. It’s designed to let moisture out but to be air/liquids tight.

It’s cheap and effective..

Also did I get it right? They’re installing the siding directly over the paper, no air gap?!

You can screw up the installation of anything. If you have doubts, I know some laborers who WILL convince you.

Apples and oranges. Old buildings leaked like grandma's colander. Recent ones are darn tight. ( My horse and buggy didn't need a mechanic. My car doesn't need a vet. ) Yes, so what? If you have a windy draft blowing through your walls, they dry easily.

Read up on "pretty good house" and the US version of "passive house" movements. Read about the "perfect wall" and fifty related topics.

https://buildingscience.com/documents/insights/bsi-001-the-perfect-wall

 

[kj_mustang]

Also, you really need a rain screen/drainage plane between the sheathing and wood siding. 2 layers of "tar paper" provide this.

Slack

Two layers of tar paper over wood sheathing is also recommended for installing under metal lathe and stone veneer.

 

[Falcon67]

I've seen pictures of Tyvek coming apart on newer houses with exposed for remodel. There may be other factors. I can say that whe I did rework on the back of our old house, the part that we think was build in the mid 70s had tar paper under the siding and it was still holding up well. The rest of the house - built in 1928 - had nothing under the siding.

 

[Ji m]

on some houses up my way,

Tyvek wrap IS the finish siding

 

[NUTTSGT]

Another back from the dead thread compliments to a now banned spammer.

 

[scottybk]

LOL, I see a new Toll Bros subdivision that's going up nearby and the fine craftsmen building that crackerbox were "installing" the Tyvek with what looked like a machete or old lawnmower blade lol.

Also you always see people throw up Tyvek and leave it exposed for months (or years lol) getting shredded by the wind, etc.

My guess is that Tyvek is probably a decent product but the hack-job manner in which its installed probably leads to its spotty reputation. It should be installed with as few seams as possible and the finish siding put on ASAP as sunlight exposure degrades it and the wind shreds it.

 

[KELLHAMMER]

True, Some building materials get a bad wrap due to the flagrant misuse, poorly executed installation. Tyvek performs very well when installed properly as dictated by the manufacturer. I have yet to hear about Tyvek trapping moisture, that's a new one!
I have seen Tyvek that has been uncovered and looked like tissue paper, pretty much disintegrated. Luckily, the homeowner didn't experienced any moisture intrusion issues. Most building products are subject to fail or have shorten life spans if not installed properly. Rainscreen design is a method that has a lot of traction and may be a installation method that becomes the norm. Especially in the wetter areas of the country