Modified bitumen is an asphalt based roofing material that comes in rolls and those rolls are either adhered to the insulation/roof deck with adhesive or hot asphalt. The seams between the asphalt rolls are torched and mated together. We don’t see alot of modified bitumen in New England, we assume the use of fire when applying the roofing plays a part. Bald asphalt has an asphalt layer with no gravel on top. After a certain amount of years the oils dry out and cause the roofing material to crack. Modified bitumen and bald asphalt roofs can either have more modified bitumen pieces torched onto cracks/holes/flashings or asphalt roofing cement with reinforcing mesh can be used. If the mesh is not used the asphalt roofing cement by itself shrinks and cracks. Coatings of petroleum based products (restaurants) or non-petroleum based products can be used to fill cracks over wide areas. These seem to last 2-5 years. Some coatings will take extra measures and may last into the 10 year range. Check for ponding (see special ponding section on other page).