You are here:

Roofing/Double-Pitched Valley

Advertisement

Expert: Bruce A. Ryan II, RRO - 7/1/2009


Question
Hello,

I am reroofing my barn, which has a valley with 2 different roof pitches.  It is about a 4:12 near the top, then gets very steep 1/2 was down at over 12:12.  My question is how do I lay roll-roofing in the valley withou cutting it at the intersection of the 2 pitches?

Answer
Eric,

The intersection of the valleys has to be cut.  install the membrane on the lower valley first, extending up onto the upper section at least 6 inches.  Cut the sheet from an angle to the center of the valley. Apply asphalt mastic to the entire transition area.  Install the upper valley liner over the lower repeating the over hang and slice, but the slice should come from the opposite direction.  Adhere the overlap in mastic over the lower valley liner ensuring that there is ample mastic at the "pin hole" that now should be left in the crux of the valleys.  Cut a butterfly shape from the membrane (elephant ears)about 6x6 and adhere that over the pin hole in mastic with one wing (ear) on the upper valley and one on the lower.

That should about do it.  This is a high load condition with a potentially weak detail, so make sure to do regular inspections.  You should lay your roll roofing over the felt underlayment which could be detailed in the same manner as an extra layer of protection.

Bruce Ryan II, RRO
Professional Roof Consultants, Inc.

Roofing

All Answers

Answers by Expert:

Ask Experts

Volunteer

Bruce A. Ryan II, RRO

Expertise

I offer solid knowlege of all types of Commercial and Residential Roofing, Waterproofing, and, Building Envelope systems. Experience ranges across low slope and steep slope roof systems. I am also well versed in matters regarding condensation and ventilation. I enjoy donating some of my time and knowledge to the betterment of others.

Experience

Bruce Ryan has 13 years of roofing, waterproofing, and building envelope consulting experience with PRC, with 5 years of commercial roofing experience prior to joining the firm. He became Vice President of the company in 1998. Bruce Ryan plays a key role in the development of practical, long-term roofing and waterproofing solutions, along with implementation of on-site forensic studies. Bruce also has a high level of experience with regard to the impacts of roofing materials and construction for demanding clients with heavily occupied structures.

Organizations
Oregon Construction Contractors Board Construction Specifiers Institute National Roofing Contractors Association The Institute of Roofing, Waterproofing, & Building Envelope Professionals Oregon Board of Investigators Installation Masters

Education/Credentials
University of Maryland BS Business & Administration Registered Roof Observer - RCI Private Investigator Certified EIFS inspector - Northwest Wall and Ceiling Bureau Certified InstallationMaster™ - The Installation Masters™ Training and Certification Program (developed by American Architectural Manufacturers Association)

©2012 About.com, a part of The New York Times Company. All rights reserved.