House Wrap

[jhagarty (Joseph Hagarty, CMI)]

@homebild

Sure.

T1-11 siding using Z-flashing is considered ‘watertight’…

Board and batten siding is considered ‘watertight’…

Clapboard siding is considered ‘watertight’…

You could go over any of these existing wall coverings in a remodeling application without the use of housewraps or felt paper and still meet Certainteed’s MIIs…

In these cases it would be an exterior siding over a pre-existing exterior siding.

@homebild

For new construction, you could actually seal all joints in the sheathing using caulks and/or waterpoof self-adhereing flashings and still meet the MIIs without housewrap or felt paper for Certainteed Vinyl siding.

Would bare OSB under the vinyl siding be considered a water tight substrate?

[mcyr (Marcel Cyr, CMI)]

**Building Code Requirements
**I am very respectful of building code development and the enforcement process, but I don’t think building codes provide clear direction in this case. Basically, all Model codes agree on the need for a weather-resistant barrier paper (usually specified as #15 felt or Grade D Kraft paper) behind stucco, brick, stone and other porous veneers. The paper requirement is typically omitted for other types of siding when they’re installed over rated structural sheathing. Alone among the codes, BOCA, in its 1998 supplement, requires a layer of #15 felt over the sheathing regardless of the siding type. BOCA has also beefed up its flashing requirements, spelling out nine areas needing flashing, and getting rid of an earlier exception for “leakproof” caulking (apparently in recognition that no caulking is leakproof for long. (See BOCA 1405.3.6 and 1405.3.10)

Marcel:)

[homebild]

Joseph Haggerty asked:

“Would bare OSB under the vinyl siding be considered a water tight substrate?”

No. Not in and of itself.

OSB or plywood could be considered watertight, however, if every seam was caulked and sealed and flashed in a manner to make the structure watertight.

Housewrap or felt paper are two ways to make the structure watertight.

They are just not the only way…

[homebild]

@mcyr

**Building Code Requirements **
I am very respectful of building code development and the enforcement process, but I don’t think building codes provide clear direction in this case. Basically, all Model codes agree on the need for a weather-resistant barrier paper (usually specified as #15 felt or Grade D Kraft paper) behind stucco, brick, stone and other porous veneers. The paper requirement is typically omitted for other types of siding when they’re installed over rated structural sheathing. Alone among the codes, BOCA, in its 1998 supplement, requires a layer of #15 felt over the sheathing regardless of the siding type. BOCA has also beefed up its flashing requirements, spelling out nine areas needing flashing, and getting rid of an earlier exception for “leakproof” caulking (apparently in recognition that no caulking is leakproof for long. (See BOCA 1405.3.6 and 1405.3.10)

Marcel:)

The BOCA Codes no longer exist and haven’t since 1999.

BOCA was merged with other model code agencies to form the International Codes Council at that time.

Nearly all US States now use the ICC codes exclusively…including Maine.

Under the current IRC 2006 version, ALL exterior wall coverings require the use of a ‘water resistant barrier’ which can be in the form of housewrap, felt paper or other approved methods.

It is clear from my example above that the current Code has taken a stricter position than even the manufacturer’s installation instructions and is quite clear in it’s mandatory requirements for a universal water resistant barrier and appropriate flashing under all wall covering types.

[poliner]

These items although sponsored explain the science behind (Tyvek) houewrap.

http://216.211.130.165:8081/code_college/Air_Barrier_OverviewO.wmv

http://216.211.130.165:8081/code_college/Air_Barrier_InstallationO.wmv

http://216.211.130.165:8081/code_college/Air_Barrier_Flashing_WindowO.wmv

http://216.211.130.165:8081/code_college/cc_thermawrap_overview.wmv](“http://216.211.130.165:8081/code_college/cc_thermawrap_overview.wmv")](“http://216.211.130.165:8081/code_college/Air_Barrier_Flashing_WindowO.wmv”)]("http://216.211.130.165:8081/code_college/Air_Barrier_InstallationO.wmv”)

[homebild]

It is also important to note, that not all ‘housewraps’ are designed to be *airbarriers *or *waterbarriers *exclusively. Housewraps can be airbarriers, moisturebarriers, both or neither depending upon the material.

Not all ‘housewraps’ are deisgned the same.

You need to consult the technical data sheet for each ‘housewrap’ product to determine just what you should expect in performance in a “housewrap”, and also the local building code and under which the product was installed to determine whether there is a problem or not.

Here are some helpful links:

http://www.umass.edu/bmatwt/search/faq_articles/faq_moisture.html

http://www.umass.edu/bmatwt/publications/articles/leaky_housewraps.html

http://www.umass.edu/bmatwt/publications/articles/watertight_walls.html

http://www.umass.edu/bmatwt/publications/articles/housewraps_feltpaper_weather_penetration_barriers.html

[pbennett1 (Peter Bennett, NJ Lic# 24G100037100)]

Joe, your link does not work.
Here’s an updated one: http://www.vinylsiding.org/publications/0804_VSI_2007Manual.pdf