Please help decipher these re-roofing bids for flat roof

I am looking for advice to help understand the bids I received to re-roof an old bldg in Chicago, flat roof approx. 1800 sf. It leaked recently when 1 foot of snow melted, but doesn’t leak with rain or a little now. The bids seem to propose different process/products that’s too technical for me to compare. Please help me compare the following bids:

  1. tear off to deck, 1/2" rigid roof insulation board, 43# base felt and fiberglass base felt, single ply heat applied resilient modified bitumen membrane, new flashing, reseal skylight with plastic roof cement, aluminum fibrated roof coating, 12 year warranty. $13,000

  2. overlay, new modified bitumen membrane, flash curbs and penetrations, fibered silver coating, coping and skylights excluded. $9,500

  3. overlay, dibiten modified bitumen membrane (in rolls 39" wide and 4mm thick), lashing base of all walls and other roof curbs and penetrations with dibiten membrane, aluminum coating, warranty 10 year labor, 20 year material. $6,000

  4. overlay, modified rubber system on entire roof and flashing walls, plastic roof cement aournd stacks and skylights, non-fiber aluminum roof coating, warranty 20 years. neighborhood contractor, $5,600

  5. overlay, base sheet, torch down modified bitumen over roof and parapet walls and other obstructions, warranty 5 year labor 10 years material, $4,400

  6. overlay, tear out blisters and 40" of flashing, apply asphalt primer on brick, install Gomco granulated modified roof torch applied over roof and parapit walls. install termination bar, apply solar seal at tops of termination bar. neighborhood contractor, $4,100

See the wild range of pricing makes me nervous. Are these bids trully different in quality or I’m just confused with the industry jargon? I know the tear off is probably the best but I plan to sell the bldg in a couple of years so only need something relatively trouble fee for 5-10 years.

Please help me analyze these bids. Also do I need to ask for a copy of their license and insurance (they all claim to be insured and licensed). Anything else I should ask them?

Thank you very much.

Im not a flat guy but to answer the question of insurances and licenses, i would ask for a copy of both and call the carrier of the insuracne to make sure it is still valid and is the proper type for the scope of work you are having done. As far as the license i would call the satte to make sure that they are still legal to work in that state and they have not had a problem with there license.

As far as going over roofs i dont ever suggest that. I would always start fresh. But im not a flat roof guy so i can really help that much.

go wth # 1 .
you dont want to recover your flat.


1…but absolutly do not let him use plastic cement on the skylights.thats a hack job in the making. dont forget if you live in the city itself your roof MUST by ordinance be white,alumimum coated,or covered with gravel or plantlife.

#1 is not a single ply. “rigid” roofing board? Who makes 43# anymore? He’s bullchitting you.

#2 is going to flash the curbs with what? What about gutter details? What about termination getails? What about base sheet and base sheet attachment?

#3 will not last 20 years…he’s lying.

#4 sounds like he’s not goimg to flash anything…the solvents in roof cement can degrade the modified.

#5 is another overlay bid…why dont these “roofers” want to tear it off and do a proper job?

#6 doesnt sound too bad, if you only have one smooth flat-lying roof on now. At least he specified aq termination attachment.

The first thing to ask for is their State of Illinois Roofing license. He is required by Illinois law to produce it upon request by ANYONE. If he doesnt have one, there is a reason for that. Also, ask for a certificate of insurance sent to you directly from their insurance agents with anopen flame rider attached, and tell the insuranc eagent that you MUST have this before they start torching your roof. If they do not have this coverage, they will most certain ly be excluded if they burn your building down.

they dont want to tear it off because of logistist difficulty,its a typical chicago 2-flat ill bet with no real access to the building.

north side or southside?

Gonna learn a few things about Chicago here…

'Da Bearsss…

I agree with roofboss, but since the contractor wants to use plastic cement on your skylights it scares me. Also, I’d want more than 1/2" thick organic wood fiberboard for insulation, which is what I’m sure they are bidding. Being in Chitown, I would think you would want to upgrade your insulation, and reduce your heating and A/C costs.

If its a typical two flat, then they probably have a cold roof assembly. Additional insulation would do no good, which is why I dont recommend you know what. I have done a bunch of these, and it can be tricky, but logistics can be worked out by the right contractor not afraid to do the work.

How much BUR is on there now? I bet there’s a lot.

Check this out.

Thanks for everyone’s suggestion so far. I got some further things to ask:

a) Is the modified granulated roof (suppose to have 12 year manufactor’s warranty) really maintenance free like the contractor #6 claimed and need no additional aluminum coating?
b) Can the granule wash off and block the gutters? Is it more difficult to apply for a tight seal since it’s not a smooth surface?
c) I have caught the neighbor’s tenants stepped onto my roof from the window of their apartment. I called the cops on them of course but you never know if they may do it again. Can the modified roof be easily damaged by occasional traffic?
d) Are additional roof vents necessary?
e) Based on your experience, are the pricing I received sound out of whack? It seems they all propose similar work with similar material, but with 100% difference in pricing.

Thanks so much. I really learned a lot and will sure make a better decision with your help!

BTW, the building is a two story (very tall though) on the south side of Chicago.

I would not say maintenenace-free, but definitely less maintenance due to not having to apply a reflective coating for a long while (about 15-20 years down the line you might consider an elastomeric acrylic, if there is no lleakage by then.

A skilled torch roofer can do it just the same…an additional step, and more time, but I do not consider it more “difficult”, just a little more time consuming.

Any roof can be damaged by foot traffic, but the granulated surface should provide better protection than the smooth.

If you overlay, I would DEFINITELY install one way breathers to release any moisture in the system if it is VERY minimal (another reason to tear off if it has been leaking)

That roof I posted pics of was sold at 15,757.00 two years ago. I think that is a good price for the tear off. I am leery of the rest.