Housewrap

[Nissan197]

Is housewrap needed when insulating with spray in foam? I have heard several say it is not needed due to the insulating factor of foam, but others say it does not hurt and to get it. I would think the foam would fill in all gaps and not allow any air through so why spend the extra money on house wrap. Opinions?

 

[RPK]

The main purpose of house wrap is to protect the sheathing of the structure from water finding its way behind the siding. In the business this is called maintaining a "drain plain" . If water finds its way behind the siding a properly installed house wrap will keep the structure dry. We all know this helps prevent rot but also helps keep mold issues in check. House wrap will also help stop the drafts associated with a crappy sheathing job. If it is not installed per mfg specs it is about useless. I haven't found many builders that know the proper way to install house wrap at the window and door openings

When I helped my son build his house we used 1/2" Dow blue board on top of 7/16" osb with 2x6 wall studs and R-19 insulation. This makes an extremely draft proof water resistant and highly insulated wall system. We taped all the joints corners and windows and doors with "Tyvek" tape. No house wrap is needed because the taped blue board is a water-proof membrane.

Sorry to be long-winded RPK

 

[ktm250rider]

What type of siding are you using? The wrap also protects the sheathing from water that can easily get behind vinyl siding.

 

[Onthesauk]

When we had our house built a few years ago, (2X6, super insulated,) the builder said they had moved back to tar paper. The wrap apparently was overkill and they were having problems with the house being sealed up too tight. Seems to work just fine, Hardiplank and deep eves, never get any moisture on the siding anyway.

 

[JasonL]

You have gotten good advice here. If the house is sheathed with any wood product (OSB/plywood) you need some type of wrap. If you are springing for the air-tight spray in foam, I would use tarpaper- if normal insulation use housewrap. Jason

 

[em14]

From the Tyvek web site ... IMHO it's a very good thing to use and to take the time to install properly.
"DuPont™ Tyvek® acts like a windbreaker and wrapped over the sheathing and under the exterior siding—cut out around windows and doors and taped securely at the seams—resists air infiltration and water intrusion and makes for a more comfortable, energy-efficient home or building."
Leo

 

[dtd24]

Always used housewrap. Doesn't really matter what type of siding is used. Works as vapor and wind barrier.

 

[EddieWalker]

For what it costs, it's very cheap with huge benifits. Off the top of my head, I think you can get a 150 foot roll for around $130. Two rolls will do a pretty big house.

Eddie

 

[HappyCPE]

I vote for the old-school 15-lb felt paper. Millions of houses built in the late 19th and 20th century can't be wrong.

However, you have to have something... As stated, you need a barrier to water infiltration to keep the sheathing dry. The felt/wrap is the last chance to stop water.

 

[RichNJKubota]

I used 30lb felt paper on my garage as I knew it would be a while before the siding went on. Went on very quick but it took 3 guys to do it safely.