Expert: Bruce A. Ryan II, RRO - 6/29/2009

Question
QUESTION: Can anyone tell me the long term performance differences, pros/cons of Modified Bitumen (MP) vs Dura-Last?

I'm looking to replace a 31 yr old flat roof that currently has asphalt and gravel. The roof is approx. 1250 ft2

MP quote was $7K, Dura-Last was $8K. MP quote would put double membrane near flashing while Dura-Last would put ply over the roof and replace the flashing.

Any comments would be greatly appreciated. Thanks

ANSWER: Dan,

The old roof should be removed regardless of the system you choose.  I do not see a whole lot of price difference and from your description, I am struggling to see an advantage or disadvantage of either system.  

I will ask you this though, how long do you want the new roof to last?  If you want it to be there for another 31 years, replace the old roof with a new one that is exactly the same.  You will be lucky to get 20 years from the Duro-last.  You may also be dissatisfied with the aesthetics of the single ply roof, so that should be considered as well.

I hope that helps,

Bruce Ryan II, RRO
Professional Roof Consultants, Inc.

---------- FOLLOW-UP ----------

QUESTION: Hi Bruce. Thanks for your response.

I would like the roof to last as long as possible with minimal negative effects from exposure to a bitter northern winter.

I've been asking and everyone has their own opinion.

The duro-last quote states a 3/8" duro-board will be fastened to the underlying deck. 50 mil duro-last will be fastened the surface of the duro-board. Seams will be hot air welded, no flame. All flashings will be replaced.

The mod.bit quote uses 4 mm APP Esha membrane, reinforced to 8mm at flashings and protrusions. A flood coat of hot asphalt will be added to resaturate the roof felts on the original roof. Damaged areas will be replaced by cutting through deck and replacing with foam insulation. No flash replacement.

As I have no roofing experience, any help would be greatly appreciated. As you mentioned, the price difference is comparable. As mentioned, I am looking for something that can withstand ice and snow.

If you need more info, I can scan and e-mail you the line per line description in each quote

Regards

Dan

Answer
The Mod Bit system will be more durable now and over the long term.  My point was that if you did not have to replace the asphalt built-up roof system for 31 years, why question it?

send me the quotes and we will go from there.  bruce.ryan@professionalroofconsultants.com