Interpretation #7415
Published October 21, 2014
Original Request
- Code Version
- 2010
- Code
- BUILDING
- Code Description
- Building
- Chapter
- 15
- Section
- 1510.3
- Topic
- Metal roof over 2 layers of shingles
Question
In compliance with Section 1510.3, Exception 1, would it be permitable to install a metal roof fastened to purlins where the purlins are fastened through an existing roof directly to the roof rafters and where the existing roof consists of two applications of asphalt shingles?
Answer Published 10/21/2014 at 2:36 PM
Yes, if the metal roof is completely separate and designed
to transmit the roof loads directly to the buildings
structural system and does not rely on existing roof and
roof coverings for support, otherwise, no per Item 3 which
specifically prohibits recovering where the existing roof
has two or more applications of any type of roof covering.
Please see the attached commentary for additional
explanation.
to transmit the roof loads directly to the buildings
structural system and does not rely on existing roof and
roof coverings for support, otherwise, no per Item 3 which
specifically prohibits recovering where the existing roof
has two or more applications of any type of roof covering.
Please see the attached commentary for additional
explanation.
Commentary
Without arguing the lack of rationality of such an
approach, or that the structures dead load may be
exceeded, the answer to the question is yes, however, the
metal roof system to be installed must transmit all loads
independently of the existing roof deck directly to the
structural support system. Consequently, an architectural
metal standing seam system could not be used, since this
type of system must be supported by a roof deck. A
structural standing seam metal roof would be required.
These roof systems have the strength and capability of
spanning structural members without being supported by a
deck.