Bitumen Roof Installation Recommendations

I am looking to install a GAF Ruberoide Bitumen Single Ply Roof and need some advice. I have two quotes that are more or less the same with one exception. The first is going to install 30lb felt and the other is not. Is the felt needed? Did someone overlook something? Is someone padding something?

Thanks, Josh

Too little detail to know.

What is the roof slope? What's the substrate...concrete, wood deck, other smooth surface......is it nailable, not nailable? How will it be applied? Hot ashpalt, cold asphalt, torch down or heat weld?

Josh

That is a low-slope roof, nailable wood deck.

How are they going to apply the bitumen roofing material?

I actually don't know. I think they are using heat of some sort since they said that the reason they don't use felt is that it is flammable. Josh

OK Josh -

There are many variations on bitumen roll roofing systems, ranging from one ply to 5 ply or more.

First, the base sheet (usually a felt, but sometimes a more expensive non-organic (i.e. fiberglass) sheet is used. The base sheet has to be attached to the deck. For plywood decks this is usually done with nails (ring-shank preferred) and 'tin caps', round tin circular washers through which the nail is placed. The base sheet is then covered with one or more plies of modified bitumen "cap sheets". It sounds like your contractors are proposing heat welding of the cap sheets, which can provide an excellent water-tight layer if done properly.

GAF's warranty periods generally increase with the number of plies. Here is a shopping list of the choices: