Indoor airPLUS

Technical Guidance to the Indoor airPLUS Construction Specifications

1. Moisture Control

Please see "How to Use This Guidance".

Sections 1.1 - 1.4

Water-Managed Site and Foundation

Sections 1.5 - 1.6

Water-Managed Wall Assemblies

Sections 1.7 - 1.10

Water-Managed Roof Assemblies

Sections 1.11 - 1.13

Interior Water Management

Sections 1.7 - 1.10: Water-Managed Roof Assemblies

Best Practice: Roof Drip-edge

Metal drip edge material should be installed at all exposed edges of the roof decking.

Detailed Illustrations: Best Practice Techniques

Best Practice - Roof Drip-edge

(Click on the image for a full-page version)

Why

Drip-edge materials protect the edges of roof sheathing from water penetration due to driving rains; the material is bent in a form that channels water away from the roof edges, thus protecting rake and fascia boards. The drip-edge material that extends past the edge of the sheathing supports the outermost edges of the shingles, enabling them to drip water while providing structural support so the shingles last longer without splitting or cracking.

How

See figures in guidance 1.9 and 1.10. Always apply the first strip of metal drip edge at the eaves, directly attaching it to the wood sheathing. Then, cover the roof decking with peel-and-stick membrane or building paper. Next, attach the drip edges to the rake ends of the roof deck, allowing these drip edge strips to cover and hold down the outermost edges of the building paper or membrane. Drip edge strips have a horizontal leg that lies on the roof deck (or on top of the underlayment covering the roof deck) and a vertical leg that is bent down 90 degrees. When installing drip edge, space the vertical portion of the drip edge strips approximately 1/8 in. from the edge of the rake and fascia boards to allow water to drip freely from the drip-edge.

References/Additional Information

Durability By Design, A Guide for Residential Builders and Designers, U.S. Department of Housing and Urban Development, Office of Policy Development and Research, Partnership for Advancing Technology in Housing, PATH, May, 2002. See www.huduser.org .
Build a Better Home - Roofs, APA – The Engineered Wood Association, 2003. See www.apawood.org/

Top of page