15 ib.tar paper... instead of tyvek ?

[jackcsr87]

I've built a 4 season room ( 12x35) on the front of my RV for winter camping. I have a few rolls of tar paper left from the roof and was wondering if I could use that on the exterior walls instead of tyvek. My walls are 1/2" plywood, 2v4's, r-13 and 1/2" drywall. I don't think it would cause a moisture problem since it works on the roof. What do you guys think? Thanx, Jack

[Rich]

Tar paper is an acceptable weatherproofing membrane for use on walls as well as roofs. Follow the same lapping principles as on a roof.

[TnAndy]

Better than Tyvek in my opinion. Had a bad experience with 20 year old Tyvek falling apart under the siding ( discoved on siding removal.....who know HOW long it had been that way.....)

[Rich]

Tyvek is quite a bit different now than it used to be.. backpriming siding (in most climates) will eliminate any surfactant damage to Tyvek. When selecting a synthetic weatherproofing membrane just make sure it's nonwoven and nonperforated.
I do agree though - there is nothing wrong with tar paper as a weather resistive barrier. The only thing I don't like about it is that once it gets wet it doesn't dry as quickly as the synthetics - giving the wall longer to absorb it. With anything you use - install it and the siding materials correctly and it'll last for years to come.