A steel roof deck supports the roofing assembly; it is not the waterproofing membrane. During reroofing, removal may reveal conditions that were not visible from the surface. Owners should establish how suspected corrosion, damage or unsuitable attachment locations will be documented and evaluated before the project reaches those areas.
Separate observation from a structural conclusion
Ask the contractor to identify what can be observed before tear-off and what remains concealed. Existing drawings, accessible underside views and prior repair records can help frame the investigation. A photograph of discoloration should not be treated as a complete structural assessment, and an apparently clean roof surface does not establish deck condition.
Johns Manville's roof-deck guidance distinguishes acceptance of a roofing substrate from a guarantee of the deck itself. The owner should similarly define who evaluates structural concerns and when that person must be consulted. If the scope involves structural repair, clarify the required design and trade responsibilities before authorizing it.
Define how unexpected work is approved
Request a written process for location-marked photographs, measurements and a proposed repair scope. Agree who receives that information and who can approve cost or schedule changes. An allowance may help budgeting, but should not replace a description of what the allowance covers and how quantities will be confirmed.
Imagine a warehouse where one area beneath a long-standing leak differs from the surrounding deck. The useful record identifies the affected bay, observed condition and review decision. “Bad metal found” is too vague for an owner to evaluate an invoice or for a future manager to understand the repair.
Coordinate the roof and occupied space
Ask whether inspection or repair requires access below the deck. Identify tenant equipment, stored materials and operations beneath the planned work area. Establish temporary protection and notification responsibilities before opening the roof, particularly where an unexpected condition could extend the work.
At closeout, retain the location plan, approved repair details and photographs before concealment. Include any changes to the specified roof attachment that resulted from the deck assessment. These records connect the concealed work to the new roof system and reduce uncertainty during later alterations.
Perkins' repair-versus-replacement guide helps frame the larger decision. The commercial inspection checklist can organize information before bids. Neither replaces project-specific structural evaluation, but both help owners ask for a scope that acknowledges what is still hidden.
Manufacturer references: Johns Manville: Systems engineering roof decks.