Flat roof advice needed, roofing old building becoming nightmare

[Johann Jells]

I'm putting a new roof on a 1,150 gross sf ft brick 100 year old rowhouse. I've had 2 highly recommended roofers in and my head is exploding.  Roofer #1 only uses PVC, and tells me he'll wrap it over the low parapets and put a metal angle over the outer edge and wrap the PVC around the chimneys. He tells the pond due to settling joists he'd abate by using thick insulation that he tapers down, but that there still might be a puddle but it won't matter because PVC is so great. He's got promotional materials for PVC and everything, a slick act.

Roofer #2 is less slick, tells me PVC is newfangled and he only uses modified bitumen (which has like 2/3 or less the life of PVC, I have no plans to sell). Then he point out that the parapets are crumbling, that the current impermeable roofing materials and paint caused the mortar to rot. I pulled out my Leatherman and put the blade into the brick joint to the hilt with no resistance. Roofer #2 also does masonry and included $7000 to rip down several courses of brick along 2 46' parapets and rebuild them. His price of $10,500 to rip the old roof and put down new seems about right, and I don't think he's hustling me for the masonry.

Does anyone have a constructive opinion on this situation? Too often owning old property requires you to become an expert in every field.

[Jamie Moyer]

@Johann Jells,

I have extensive experience with MB roofing on flat roofs in Chicagoland. IMHO it is imperative you rebuild the parapet walls before roofing. Tuckpointing only, will not be a solution that will last. Without seeing your roof, I can guess what has happened. You might not have noticed, but, I would be willing to bet that if you look closely at the parapet walls, you will notice that they have started to lean inwards toward the center of the roof. If you have clay coping tiles, they will be leaning inwards also. Some cheap contractors will try to sell you tuckpointing to fix this - it will fail within 5 years. To be properly repaired, the firewall (parapet) needs to be rebuilt down to the roofline so that it is plumb. The water from the coping tile should fall straight down to the sidewalk without landing back on the wall. Masonry walls need to breathe. That's why roofer 2 says not to wrap. The proper way to terminate a MB roof is with a termination bar wrapped with a counter-flashing. For more info regarding parapet and masonry walls I highly suggest heading over to buildingscience.com and check out what Joe Lstiburek and his colleagues have to say. Best of luck.