pool of water on flat roof

[Kyle]

This is more of a my Father's house repair question...

The church where I'm the new pastor has a flat roof connecting two older buildings - the flat section was constructed in the 1930s when flat roofs were all the rage.

The roof was replaced 17 years ago with a vulcanized rubber roof, and a pitch of about 2% was put on it for rain and snow run-off. The roof material is in good shape (thank the Big Guy!) even though the roofing company closed a few years ago (the owner retired and dissolved the business instead of selling it).

Here's the question: near where the drain hole is for run-off at one end of the roof there is a low spot, and rain run-off forms a pool there about 12 feet (3+ meters) in diameter and a depth of about 2 inches (5cm).

Short of ripping up that section of the roof and redoing the underlayment to eliminate the low spot, does anyone have suggestions on how to get rid of the water on a regular basis? Anyone know what effect that water and sunlight is going to have on the rubber over time?

Thanks!

[SJF]

It's probably Butyl, a synthetic rubber well suited for the kind of situation you have observed. It's used for roofs, pool liners, etc. and is essentially unaffected by ultraviolet radiation which is fatal to rubber.

Some information at --

SJF

[Dean]

I've worked in a church or two and some have very nice cielings,an older church could have a nearly impossible to replace cieling material. I was a helper on a flat roof crew in the early 90s,We used EPDM by Firestone as one of the membrane materials..Sometimes a variety of foam sheeting was mechanically fastened (large thin washers and long screws) and the EPDM glued to that total surface..If You went this route the hole could be built up and allow water to flow to the scupper or roof drain,,,but,,,it would still be a patch.. I would leave a non-leaking roof alone unless there is material or furniture,keepsakes etc that cannot be replaced under the worrisome area. Back then(90s)yellow glue was used between rubber and other material and black glue was used for rubber to rubber applications and then a special black caulk tooled over all edges of a patch,,tooled in a way that allows water to flow over it.. Black rubber heats up fast and evaporates water quickly in the sun but 2" deep water in an area that large could do lots of damage inside if it developed a leak.. Are there any flatroofers in Your Flock? They could tell You for sure about the above idea of building it up on top of a good membrane better than I can..I was just a helper for about a year there and only about 6 months on the flat roofs before I found something else to do.. Dean