Westcon

Condensation Related Wood Rot & Mold Growth
The Under Appreciated Role of Air Intrusion
Presentation By: Phil Dregg er, PE , REC
Technical Roof Services, Inc.

Each year many seemingly well-designed and constructed roofs/walls experience wood rot and mold growth from excess accumulations of “condensation” even in moderate climates such as the San Francisco Bay Area. In many cases roof/wall “leaks” or “excessive interior Rh” are blamed when actually the cause is rapid infiltration of large amounts of interior air (not excessively humid) into insulated spaces which contain cold surfaces. The purpose of this presentation is to help Architects and Building Envelop professionals better understand the forces that work to drive interior air into framed roofs/walls, to identify common “moisture trap” conditions, and to offer tips to help avoid condensation related and damage.

The presentation will include:

Energy code and building code requirements (including recent changes) related to moisture vapor transmission and air/vapor retarders.
Discussions regarding how water vapor moves into and out of (or not) roof/ceiling and wall assemblies.
Design tools/guidelines available to Building Professionals
CRREL “Retarder Guidelines”.
ASTM C755 “Standard Practice for Selection of Water Vapor Retarders for Thermal Insulation”.
ORNL/IBP “WUFI – Moisture Design Tool For Architects and Engineers”.

Several case histories showing how uncontrolled air intrusion led to damage originally alleged to be due to other causes. Phil Dregger, a long time Westcon member, is a registered Professional Engineer, Registered Roof Consultant, and President of Technical Roof Services, Inc.. Mr. Dregger received his Masters of Science Degree in Civil Engineering from the University of Minnesota. Prior to coming to the West Coast in 1989, he investigated condensation, wind, wall and roof covering failures for Twin City Testing in St. Paul, Minnesota.

A past Director of the Roof Consultants Institute and a former faculty member of the Roofing Industry Educational Institute, he serves on the executive committee of the special ad hoc Roofing Industry Committee on Wind Issues. He is the author of several articles on roof technology and has lectured to industry groups sharing lessons learned from his many investigations