Considerations for the Designer
When designing a water cooled, water retaining or retarded drainage roof assembly, certain design criteria must be considered.

NOTE:
  1. Due to extremely heavy weight loads normally associated with retained water, poured and precast concrete or other heavy load bearing decks must be specified.
  2. Roof structure design for live loads shall be a minimum of 50 psf (22.7kg/.09m2) and deflection shall not exceed 1/360 of the span, both in addition to the anticipated weight of the water. Insulation joints must be taped in single layer applications. Vapor retarders must be two plies and solidly mopped.
  3. At points where water pressure from a spray system may be excessive, the roof surface should be protected with treated board platforms or other suitable construction to break the force of the water. Wood platforms should be laid on top of protection board over the roof surface and not fastened to the deck.
  4. Insulation under a water cooled roof should be a type which is rigid and dimensionally stable with a high compressive strength.
  5. It is mandatory that the water cooling system be closed down and the roof drained prior to freezing weather. Neither roofing nor the structure will withstand the expansion caused by ice formation.
NOTE: Responsibility for design of any roofing system remains with the architect or engineer and building owner.
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