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WRB Installed Vertically

my250r11

my250r11

Sawhorse
Joined
Feb 16, 2015
Messages
1,039
Location
Roswell, NM
I have a roofing contractor wanting to install the WRB vertically on a steep roof. I can not find anything in manufacturer installation instructions about this type of application. He has sent me information from the NRCA stating that in some situation on steep roofs it is ok. The code book says parallel to the eaves. Does the code allow this alternative installation if the laps are correct? Your input would be greatly appreciated. I have also sent the question to ICC.
 
Last edited:
WRB? Weather Resistant Barrier?

Guess I am behind the times............are we talking ice barrier?
 
& o & o &

WRB = Water Resistive Barrier.........WRB's are defined in Section 1404.2
in the `12 & `15 IBC, and [ generally ] intended for application on walls.

Roof assemblies use "Water Resistive Underlayment"......Please refer to
Section 1507.2.8 in the `15 IBC.

Regarding the information the roofing contractor has provided to you,
does that information have a listed Standard, such as ASTM D1970,
another ASTM Standard, or another recognized [ accepted ] Standard
[ ANSI, U.L., FM, other ], or only a recommendation from the NRCA ?

Here is a Link to an article from the 2005 Professional Roofing Magazine
regarding installing underlayment vertically on high sloped roofs:
Refer to Page 4 of 5.
http://www.texasinspector.com/files/Underlayment-NRCA.pdf

The Term used in this particular article for applying underlayment
vertically is called "strapping".

"In certain geographic locations and under extenuating circumstances,
an underlayment may be installed in vertical runs.......This is referred
to as "strapping."...........If strapping is used, NRCA recommends the
sheets be offset at a slight angle to promote drainage.........Side lap
and end lap coverage should be increased, as well.......Generally
speaking, strapping should be limited to steeper slopes that are more
difficult to cover with horizontal runs."

Also, will the roofing contractor provide the owner a valid Warranty ?

& o & o &
 
That is the only thing he has supplied so far is that exact same article. Agree it is not a standard.

Yes, I'm referring to the underlayment (felt) before the shingles.

He has yet to supply me with something from manu., UL, etc.

At this point I'm not going to allow it.
 
I would agree with you. I'd want to see some testing or the manufacturer's installation address this before I consented to it. What are the "extenuating circumstances" driving this installation method?
 
Thought it was to prevent water from entering the structure. On a steep roof there may be an install advantage to run it vertically but that's not the products intention to make it easier to install. I have seen the WRB installed vertical on roof rakes, with drip edge over it. Also seen it in valley's but not vertical across a roof as indicated. Manufactures installation directions would prevail IMO.
 
tmurray said:
I would agree with you. I'd want to see some testing or the manufacturer's installation address this before I consented to it. What are the "extenuating circumstances" driving this installation method?
Click to expand...

Nothing other than easier for the installer, which IMO isn't a reason to violate the code or manu. instructions.
 
Depending on the covering and the wind loads the code does address the application direction


Asphalt shingles

R905.2.7 Underlayment application.
For roof slopes from two units vertical in 12 units horizontal (17-percent slope), up to four units vertical in 12 units horizontal (33-percent slope), underlayment shall be two layers applied in the following manner. Apply a 19-inch (483 mm) strip of underlayment felt parallel to and starting at the eaves, fastened sufficiently to hold in place. Starting at the eave, apply 36-inch-wide (914 mm) sheets of underlayment, overlapping successive sheets 19 inches (483 mm), and fastened sufficiently to hold in place. Distortions in the underlayment shall not interfere with the ability of the shingles to seal. For roof slopes of four units vertical in 12 units horizontal (33-percent slope) or greater, underlayment shall be one layer applied in the following manner. Underlayment shall be applied shingle fashion, parallel to and starting from the eave and lapped 2 inches (51 mm), fastened sufficiently to hold in place. Distortions in the underlayment shall not interfere with the ability of the shingles to seal. End laps shall be offset by 6 feet (1829 mm).
 
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