RAINTROL® SPECIFICATIONS
The RAINTROL® drain is offered in two basic designs. The three inch high weir is principally for flat roofs. Though this may be used on sloped roofs, the limited factor is the build up which can not exceed 3". The second design is the six inch weir which can be used on all roofs up to and including a sloped roof with a 6" rise. The flow rates for all RAINTROL® drains are shown on Table 2.

NOTE: The roof drains are supplied in increments of weir openings. They are shipped from the factory with the correct weir openings in accordance with the specifications.

However, should some requirements or conditions change, the drain can be adjusted. Vandal proof fasteners prevent unauthorized tampering with the setting.

Included in this section are tables of data for a number of localities. For locations not listed, use values for similar or nearby locations. For specific conditions which require more information, contact Jay R. Smith Mfg. Co., Montgomery, Alabama.

Raintrol Diagram

DRAIN SYSTEMS

DESIGN CONSIDERATIONS

The engineer should lay out the roof drain system consistent with the structural design strength of the roof. Normally for a flat roof with a 30 lb. sq. ft. design load, the water depth or build-up would be limited to 3". This will keep the load down to approximately 15 lbs. per square foot. For sloped roofs, the allowed water depth can be greater, but only to the point where the stresses will be within the design limitations. This will be up to the discretion of the engineer.

The roof drainage design can be based on a number of factors. The prime consideration could be economy, using minimum leaders and storm sewers. The allowable roof load or build-up could limit the design. Or possibly, drain down time could be the limiting design criteria. In any case, knowing the maximum flow rates, which are controlled, the engineer can properly size leaders and storm sewers economically consistent with his selected design criteria.

 When designing the roof drain system, the engineer must remember that the roof is being utilized as a temporary reservoir to retain some water. Flashing and water proofing should be high enough to prevent any leakage. The engineer must also provide adequate strength for structural safety. In addition, the following considerations should be observed:

These are not absolute requirements, but are suggestions to be considered. The final design is at the discretion of the design engineer and should be consistent with the roof requirements.
    a. On all roofs, use minimum of two drains, if possible.
    b. On larger roofs, use a greater number of drains as dictated by design layout.
    c. Limit roof area to 25,000 sq. ft. per weir opening.
    d. Recommended maximum distance from roof edge to drain is 50 ft. (flat roofs).
    e. Recommended maximum distance from end of valley to drain is 50 ft. (sloped roofs).
    f. Recommended maximum distance between drains is 200 ft. g. Provide adequate flashing at parapets, openings, walls, joints, etc.
    h. Limit parapet walls or provide overflow scuppers. These should be located at the anticipated maximum water depth (build-up). If located in a higher position which could result in a greater flow rate, piping must be sized accordingly.
    i. Consider wind effect in locating the drains, and the number of drains.
    j. Possible roof deflection due to load. This could create low spots and adversely affect drainage and/or structural safety.
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