01 May 1999
a. General. The big difference between reroofing and new roofing is the fact that the building is now
occupied. The designer must not only consider the technical aspects of the new roof but disturbance and
safety considerations as well. Appendix 11-1 provides examples of concerns that must be addressed in a
(1) Hidden Damage. It is likely that previously undetected substrate damage will be discovered
during the tear off. Replacement decking and lumber for curbing should be readily at hand.
(2) Construction Damage.
Control of debris is difficult. Routes for demolition should avoid
tracking over newly applied roofing.
(3) Substrate Integrity. Re-covering requires a sound deck and adequate adhesion of the
existing system (unless the new system will be fastened through the old system). The existing insulation
must be strong enough to withstand construction loads and must not be wet.
Anticipate bad weather. Tear-off only as much area as can be completely
replaced that day.
(5) Fasteners. Verify that fasteners are penetrating the deck as specified. On steel decks,
fasteners should penetrate the top flange of the deck, not ribs. Run pull out tests to confirm specified
(6) Through-Fastening. Installation of new structurals for conversion to standing seam metal
roof requires anchorage into building structural members. Penetrations must be sealed daily.
b. Pre-roofing Conference. A conference should be held prior to construction. Representatives of
the designer, user, roofing contractor, general contractor, materials manufacturer, field inspector and
other related subcontractors should be present. Discussions should include protection of the new
membrane after installation and how nightly water cutoffs will be installed. (Refer to suggested Agenda
Items in Appendix 11-1.)
c. Shop Drawing Submittals. Drawings of intersections of expansion joints, curbs, edging, flashing
and coping should be required. These should be dimensioned, not copies of manufacturer's standard
d. Design Submittal Requirements and Checklist. The reroof system should be provided as a
complete system, including anchorage through the existing system if applicable, fire ratings for total roof
system (re-cover and existing), replacement of base flashings, reuse of counterflashing metal, and
separation of new and old work.
(1) Manufacturer Acceptance. Require the manufacturer to verify in writing that the proposed
system is compatible with the roof deck, vapor retarder, insulation and is appropriate for this specific
(2) QA Inspections. On major roofing projects require quality assurance inspection.
(3) Code Compliance. Require evidence of compliance with fire ratings, wind loads, or other
specified code requirements.
(4) Metal Reroofing Checklist.