Commercial Flat Roof problem - leaks

60+ year old flat tar roof - 3 layers. Roof was silicone coated 6 years ago and has continued to leak - only around all pipe vents. Every year it requires patching but still has issues. Roof definitely has moisture trapped. Suggestions? Solutions?

My first response is the recommendation that the old roof is torn off to the deck and a new one installed. Patching a 60-year-old roof with silicone is insane.


2-way vapor vents. “just say no to silicone”, if they’d used asphalt fibercoating it would be good yet.

7800 square foot roof - 1st quote tear off/EPDM was out of the stratosphere…$180,000 ($23/ft). 2nd phone quote said $8-10 foot for tear off & new EPDM. Can there really be such a huge difference in pricing?

would never do silicone again in retrospect. Don’t know much about asphalt fiber coating, can this go over silicone?

Few “roofers” consider the whole system, coatings are easy. Salesmen promise anything to move product. Silicone is like herpes, you own it! I’ve seen quite a few failures with silicone as far as disbonding and condensation. Your second bid was a fly by. Start tearing off and then all the little “problems” and upcharges kick in…Get more bids… Where in the country are you?

Get more quotes. The roofers should give you a bid with all the work they propose doing shown. Hard for this community to give you advice on price without knowing where the job is located. Also, there are major material shortages in the roofing business. Prices are escalating.

Yes, Silicone was a big mistake. In New Jersey.

$23 a foot may be completely reasonable depending on the exact roof, what they proposed to do, and what is being torn off.

Wood prices have tripled when you can get any. Steel has skyrocketed. We have seen price increases 5 times in the last 3 months each time anywhere from 5%-30% increases. These are from your major commercial roof manufacturers. No one can get any major insulation deliveries until December now and no one is holding their prices without a purchase order.

$8-$10 a foot for a tear off in NJ is also not going to happen from anyone who actually installs a roof correctly.

Silicone over asphalt is a bad idea, over coal tar pitch is even worse as the pitch will destroy almost any type of coating that isn’t asphalt based.

Is this gravel or smooth built up? Is it actual coal tar pitch or is it asphalt? What is the roof slope in the deck if there is any? Is the building climate controlled? How does the roof drain? How many and what kind of penetrations are there? What is the deck and does any need replaced?

There are tons of options for replacing flat roofs and what you need can only be determined by someone who goes out and looks at it and knows what they are doing. My advice is to contact your local Firestone representative and have them help you invite contractors and come up with a scope of work. Firestone has TPO, EPDM, just released PVC, APP, SBS, Fleeceback, and Metal roof systems.

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Without seeing the existing, you may consider SPF sprayed foam on top of existing. It will almost certainly require a layer of 1/2" product or a “base sheet” to seperate the foam from the asphalt.

It is self flashing around pipes ect. so no additional flashing required.

Light weight and good insulation too. Would need to coat with an elosomeric coating to provide UV protection.