Construction Considerations and Alerts

CEMP-ET

TI 809-53

01 May 1999

(b) Wood: Rotting? Warped? Shrunk? Excessive joint gaps? Unanchored?

(c) Structural Concrete: Excessive deflection or wide cracks? Sharp fins (raised knife-like

edges or folds in the concrete)?

(d) Precast Concrete: Excessive joint gaps? Differential deflection at adjacent units?

(e) Poured Gypsum: Excessive deflection of subpurlin bulb tees? Cracking? Evidence of

excess moisture or loss of binder strength? (Can create a reroofing hazard.)

(f) Adequate fastener withdrawal resistance?

(g) Corrugated Steel Supporting Lightweight Insulating Concrete: Underside venting slots

present? Efflorescence at slots or laps?

(h) Structural Wood Fiber: Excessive deflection? Differential deflection between adjacent

units? Excessive joint gaps? Evidence of moisture degradation or loss of binder?

(2) Roof Insulation.

(a) Use destructive tests (roof cuts) to determine condition and attachment of components.

(b) Conduct moisture surveys using infra-red (IR), nuclear, or capacitance techniques.

(3) Rooftop Assessment.

(a) Ponding? Drains plugged? Drains located properly, not blocked by curbs?

(b) Flashing height adequate? Flashing damage? High enough to accommodate increased

insulation or slope?

(c) Evidence of accumulated stress at re-entrant corners, flashings, penetrations, or joints?

(d) Punctures or repairs indicating chemical attack, abuse or excessive roof traffic?

(e) Equipment mounted properly? Clearances adequate?

b. Roof Replacement.

(1) Can a new system comply with Factory Mutual, UL, and other requirements?

(2) Are all flashings to be replaced?

c.

Roof Re-cover.

(1) Should new membrane be isolated from existing?

Should loose aggregate be removed?

Has a moisture survey or core cutting revealed wet insulation?

(2) Is the structural design capable of supporting the weight of an additional roof system?

11-4.

CONSTRUCTION CONSIDERATIONS AND ALERTS.

11-6