I'm changing out some shingle siding and need to replace the underlayment. The shingle siding is over felt that is over wood clapboard siding.

I am putting Hardieshingle up over the wood clapboard. Is it better to replace the felt with new felt or use a Tyvek housewrap? The big difference on the surface is the cost, but I have no experience using housewrap.

I think tyvek is what Hardi would recommend using underneath there. Tar felt is organic, as are shingles. Tyvekk and Hardi are inorganic and do not breathe.

Use is simple. Staple in place with NO bagginess. Tape over any seams and all staples with the appropriate tyvek tape.

Tyvek is a superier product but don't staple. Manufacturers specs require button cap nails.

The roll of Tyvek I bought tonight specifies staples as an acceptable means of installation.

[This message has been edited by Ryan the Temp (edited 10/9/2010 8:09p).]

I might be willing to buy 20-30 feet from you if you have enough left over. Did you get the 9 ft wide roll? Is it Tyvek brand or an off-brand?

Staples can be used with Tyvek AS LONG AS you cover them with tape.

Button-cap nails should self seal well enough that you don't need to tape the nails. All depends on how much effort you want to put in; I needed to tape seams anyway so I had the tape, I had a staple gun already, and I really didn't want to hammer in a hundred button-cap nails.

Jamesf -

I bought the 3' X 165' roll. I may end up taking it back, though. The felt behind the existing shingles is in really good shape for being 50-60 years old. I also only need about 50 feet. I have yet to decide, but I will know this weekend when I get scaffolding set up and it goes much faster.

I may also consider putting Tyvek over the existing felt since the felt does have holes from the old shingle nails. I don't believe the shingle nails went all the way through the wood clapboard.

Should I decide to break the seal on the Tyvek, I'd be glad to sell you some or all of the rest. I paid $.418 per LF for reference.

Good call guys. I stand corrected about the staples with tape!

Tyvek does breathe....
I would not spend too much time taping either.....when you nail on the siding you will be punching lots of holes in the tyvek. Some architects are starting to question the use of tyvek (or any housewrap) anymore.

Here's a pic for reference. I will add more later. The shingles went all the way up the side and gable. I installed 1X8 all the way across with a drip cap and flashing to visually separate the gable. Next step is to finish removing teh rest of the shingles up top, replace the gable vent, and install Hardieshingle half-rounds on the gable.

The roofing felt still looks good after +50 years.

The old types of felt were much heavier and better at resisting moisture than the new felts. I would not put Tyvek over the felt. Any time you use two vapor retarders or barriers in the same assembly, you can run into moisture problems although in your case that probably won't happen. Based on the age of your house, tyvek isn't going to help you much. You probably have air leaks in plenty of other places. Besides that, Tyvek doesn't work properly when it has asphalt on it. I would consider putting another layer of felt paper because your old felt has a jillion nail holes in it. It also looks like the original installers did a good job because they have a piece of felt at every joint. Better yet, uncover the original siding and that house will look great after about 1000 manhours of work.

[This message has been edited by Builder93 (edited 10/23/2010 11:35p).]

quote:

---

Better yet, uncover the original siding and that house will look great after about 1000 manhours of work.

---

I would love to, but yeah - super PITA. It was our original plan, but we had a lot of problems trying to get the paint to stick on the front after we uncovered the clpboard. We decided to have only clapboard on the front for now so we can get it painted sooner.

It would also be more expensive to insure because I live in Harris County and the insurance companies strongly prefer cementitious siding,and in some cases require it.

If you are into that sort of thing, I would not be scared to put tyvek over any other barriers. Tyvek has a high perm rating (its a weather barrier, not a vapor barrier) so you should not have any vapor trap issues. I say, if you are into that sort of thing, because I do not fully endorse the functionality of Tyvek. The only reason I use it is because I have to in order to keep my siding warranty in place. Note: I am not a builder or an architect.