Modified bitumen — mod bit — is a tough, multi-ply asphalt membrane found on many commercial buildings and residential porches across Atlanta. We repair it, coat it, and replace it.
5.0 ★ · 130+ Google reviewsA+ BBB RatingGAF Certified ContractorDuro-Last Authorized DealerAttic Armor Certified InstallerLicensed + Insured · GA GBL-0523-21153As seen on CBS46 · Better Call HarryOpen 24/7 · 365 days5.0 ★ · 130+ Google reviewsA+ BBB RatingGAF Certified ContractorDuro-Last Authorized DealerAttic Armor Certified InstallerLicensed + Insured · GA GBL-0523-21153As seen on CBS46 · Better Call HarryOpen 24/7 · 365 days
A finished modified bitumen roof on an Atlanta home, with new pipe boots set into the cap sheet.New metal counter-flashing where the modified bitumen meets the chimney - the detail that keeps a low-slope roof dry.
Common mod bit problems
Blisters from trapped moisture or poor adhesion
Open laps and seams
Cracked or alligatored surfaces where granules have worn off
Flashing failures at walls, parapets and rooftop units
Ponding water at low spots and clogged drains
Repair or replace
Localized blisters, seams and flashings are repairable. When the cap sheet is worn across the roof but the system is dry, a coating can restore it. When the insulation is wet or the roof has been patched over and over, we'll show you why replacement is the better spend — and compare mod bit, TPO and PVC so you can choose.
Frequently asked questions
How long does a modified bitumen roof last?
Commonly 15–25 years depending on the system and maintenance.
Is mod bit good for a residential porch roof?
Yes, it's a solid choice for low-slope porches and additions, as is TPO.
