Flat roof materials question

Hi everyone! I am currently getting estimates from roofers and I am not sure which material would be best for my residential flat roof in NYC.

A roofer came in today and said that there is no need for a new roof, an overlay would be fine. He suggests either Firestone SBS cold applied roofing or Gaco silicone roof coating.

The roof gets very little foot traffic. The only time anyone goes up there is to clean the gutters. It does get a lot of sun, though.

Which material would be better? Is there another material that is preferable? I am a newbie at this and any advice would be appreciated. Thanks!

Please Upload some pictures.


Gaco is a coating, not a roof. Firestone SBS is a great product, might be more than you need. Make sure it has at least 1/8" per ft slope with the SBS.


Hi MPA, since I’m a new user I am only allowed to upload one photo.

It’s already aluminum coated, nothing is going to stick to it.

1 Like

To properly install a new roof or add a layor to the existing all of the coping tiles will need to be removed and reinstalled. Looking at the picture and the height of the skylight curb, it looks you already have several layors of roofing. Going over that roof would likely not meet code or be a good long term investment.

1 Like

Thank you Dtris and MPA!

I agree with you MPA. We asked the roofer about tearing off the layers. I also want to see if there is any rotting wood that needs to be replaced. He kept saying that it wasn’t necessary and an overlay was fine.

In regards to roof replacement, he said that we would need to find an asbestos removal company. I guess I’m on the search for a good asbestos removal company as well.

Another contractor is coming on Wednesday to give an estimate. I will ask for more details about doing a proper roof replacement.

I think He is a bullshitter.
I am not buying the asbestos.
That is hot mopped modified bitumen.
Did he take a core sample?
I think you still need to find a roofer.

Why are you wanting to replace this roof?
It might only need a new aluminum roof coating and repair around protrusions.


Totally agree with roof lover, is it leaking?. Your best bet might be to do some minor repairs and a new coat of aluminum coating. Silicone would be a waste of money imo, to properly convert to and install a silicone system, the required way to actually have a warranty, is not at all cheap. In my area guys who just throw another layor on top tend to not do a good job and normally doesn’t last more than 3-5years.

It is pretty rare that you need an asbestos abatement contractor on a residential roof. I think you should shop around for a different roofer.

1 Like

Hi roof_lover and MPA, you are right. Two more roofers came to take a look. Asbestos is not an issue.

The roof has a few layers already. The last layer was put in 1999. We do have a leak, but it may be coming from the facade of the building (brick pointing needed on all the cracks). And the leaking only occurs during very heavy rain. And not from the ceiling, but through one of the window frames.

Out of four roofers that have come to give an estimate, only one examined the ceiling to check if we had any evidence of leaks. When we told him we had three layers of roofing already, he was the only one who said that we needed a roof replacement. All others insisted that an overlay was sufficient.

I’ve been a member on roofing.com for a couple of days now. The site is letting me add more photos. We do have a lot of cracks on the surfaces.

Update on the flat roof project. A contractor gave me a quote of $10 / sq ft. This is for a roof replacement. Roofing material: GAF Ruberoid MOP Granulated (Black/White) SBS cap.

Along one side of the roof are shingles. It’s been many years since they were last replaced. The contractor gave me a quote of $1000 for 600 sq. ft.

It was originally $2000, but he said he gave me a discount. I have been reading about how roofing supplies are becoming more and more expensive. Is this a good deal, or should I negotiate further?