02:31PM | 02/21/08
Member Since: 01/24/06
1449 lifetime posts
I was asked to check a newly installed roof in upper Manhattan and noticed how some so called roofer had installed some really poor quality drains.

No ASSE /ASTM markings and its a mystery of where they were made let alone metal composition as they appear to be white metal which should last almost 3 or 4 years at best.

To make matters worse he installed them by means of sleeving the new drains inside the existing cast iron ones thus not only reducing the capacity of the storm system but he just created a condition where the drains are higher then the roof membrane and causing a severe ponding condition*(1)

By sleeving a drain instead of replacing them the insert is now set between the drain inlet and the outlet pipe so when a stoppage does occur the storm water rises and flows under the membrane and causes severe leaks inside the building and now he had to install scuppers to help drain the roof.

Also sleeving reduces the ability of the drains to allow for proper drainage as we size roof drains by the square foot area, pitch of the roof surface and based on a 10 year average flow rate we just don't say this looks like a 3" or 4" drain.

Sizing has to be calculated and sleeving defeats the original design.

The dome he used are as thin plastic not even decent quality poly and no locking capabilities so it will become dislodged allowing debris to enter the leader line.

The reason I use JR Smith CI drains is I detest call backs and I like the idea of bayonet type locking device on the combination gravel stop and retaining ring. (not used on promenade drains)

The Smith bayonet device allows easy removal yet cannot loosen on its own and the other brands that use bolts to hold the dome down rust over a period of time and then the dome is impossible to remove when rodding is needed.

Roof drains are subjected to conditions that normal plumbing would never come into contact with and indoor plumbing is only guaranteed for one year after completion, yet I have to give a 20 -30 year guarantee so quality has to be the best at an affordable price.

Roof drains are subjected to ice, chemical attacks by cooling tower chemicals and acidic conditions as the soot from oil burning boilers mixed with water creates sulfuric acid which corrode less then top quality drains.

Even epoxy coated drains made of thin CI do not hold up after a few years exposed to 4 seasons of mother nature very hot sun then cooling rain (sun showers) many simply crack as there is no integrity in the metal as they depend on a thin coating for durability

Why I use CI domes is to prevent the dangerous conditions that occur during the winter months where you have debris around the drain normally dead pigeons*(2) and feathers and ice or snow build up and the domes add the extra protection of allowing some water to flow even if the area around a drain is frozen or partially blocked.

Water weighs 62.5 pounds per cubic foot (7.48 gallon) and many roofs are rated for only 125 PSF which does not leave much room for error.

The key to a properly installed roof drain is not only the 4 PSF sheet lead flashing but the ability to lock the lead in place with a combination gravel stop and retaining ring using larger bolts then some manufactures use.

It makes no sense to spend $100,000+ to re roof a building and then skimp on quality drains that should outlast the roof.

Some of the drains I installed the surface was re roofed several times using the same drains. If the drain should fail before the roof shame on the installer and the person who did the specifications.

The picture is a JR Smith 1330 drain I installed over 22 years ago on a set back a 24" ledge 18 stories up on a Manhattan commercial building.

As you can see no one in their right mind would want to have to replace that drain for another 80 years and the ability to lock the dome in place is very critical in these types of applications.

1* ponding is water build up on a roof surface

2* pigeons drink cooling tower water and die on the roof surface and as they decay the heavy rains make the feathers flow to the lowest point where the drains are located.

Respectfully,Sylvan Tieger, LMP /LMFSPC


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