Instead of re-roofing your old flat or low sloped roof, consider a roof coating. A roof coating creates a liquid applied, monolithic, fully adhered, and elastic waterproof surface.
Roof coating is seamless, permanently protecting against leaks, ponding water, and the damaging effect from the Sun and severe weather.
Many roof types can be coated. Metal, single-ply, and modified bitumen are most common. Ballasted and gravel surfaced roofs can be coated after removing the ballast and spray foaming the surface.
Coating a roof is better for the environment. The old material is not removed and transferred to a landfill.
Learn more about roof coating.