please help this new homeowner w/4 y.o. roof

Old 09-30-01, 02:32 PM
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Join Date: Sep 2001
Location: Philadelphia, PA
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I just bought a big townhouse. It has a 15 X 40 flat roof. It also has drywall screwed directly to the roof joists so there is no ventilation between joists - or anywhere for that matter.

During the purchasing process, I walked the roof and it was alligatored from front to back. The seller cold-coated the roof to appease me. Three months afterwards, the coat he put on is still semi-liquid. He must have put it on really thick because it's 1/4" thick or more in spots. I think he said he applied 40 gallons to the roof. It is starting to alligator again with liquid inside each one.

Two questions:

1. Am I forever doomed because the roof has no ventilation?

2. Should the cold coat still be liquid in the middle?

Thanks for your help.

Old 09-30-01, 11:50 PM
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Most cold-applied roof coatings will cover from 3-5 squares per 5 gallon container. In your case the roof is 6 squares so two 5 gallon pails should have been plenty. Some coatings will stay soft and pliable for quite a while especially if it is common asphalt roof coating. Asphalt is not UV resistant so if left exposed to the sun it will continue to alligator. This is because the oil properties of the asphalt are drying out and it is shrinking into itself. Asphalt must be protected with either an aggregate such as gravel, or a coating like aluminum coating. The cheapest thing you can do right now is to let the existing coating cure until you can walk on it and then coat it with fibrated aluminum roof coating. The fibers will help to bond the material together especially over bad areas. Ten gallons should do it! As far as venting the area under the roof, there are breathers made for flat roof applications but you would need one between each joist. You will have to find some way to vent the area through the eaves or exterior walls. It may not be easy though.

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