For most South Florida flat roofs, TPO is the choice for reflectivity and cost, modified bitumen for toughness and foot traffic, and built-up roofing for redundancy on roofs already built in asphalt. The right one depends on how the roof is used, what’s on it now and how it drains.
Side by side
See also:Commercial & flat roofing →| TPO | Modified bitumen | Built-up (BUR) | |
|---|---|---|---|
| Typical life in Florida | 15 to 22 yrs | 15 to 20 yrs | 15 to 25 yrs |
| Heat | Highly reflective | Depends on surfacing | Depends on surfacing |
| Foot traffic | Moderate | Strong | Strong |
| Repairability | Hot-air welded patches | Torch or cold-applied | Hot asphalt patches |
| Seams | Heat-welded | Lapped and sealed | Multi-ply mopped |
How we choose
- What the existing assembly is and how many layers it has
- Whether the insulation is dry
- Rooftop equipment and foot traffic
- Drainage and ponding history
- Budget and how long the owner plans to hold the building
We identify the existing assembly first, then recommend, not the other way around.
Whichever membrane you choose, the complete assembly must carry a product approval valid for the High-Velocity Hurricane Zone.
TPO in more detail
TPO is a single-ply thermoplastic membrane with heat-welded seams. Its light color reflects sunlight, reducing rooftop heat gain on Florida buildings. It can be mechanically attached or fully adhered, and patches can be welded in years later.
Modified bitumen in more detail
Modified bitumen is an asphalt-based sheet reinforced with polymers and fabric, installed in multiple plies. The layered build is tough under foot traffic and around equipment, which suits roofs that see regular service work.
Built-up roofing in more detail
Built-up roofing, also called hot mop, layers hot asphalt and reinforcing felts to create a thick, redundant membrane. It has a long track record on flat roofs and is a natural fit when re-roofing over or replacing an existing built-up assembly.
Drainage matters more than the membrane
Standing water shortens the life of every flat roof system. Tapered insulation, crickets behind equipment and clear drains often do more for a roof’s life than the choice between membranes.
Frequently asked questions
Which is better, TPO or modified bitumen?
TPO for reflectivity and cost; modified bitumen for puncture resistance and foot traffic.
How long does a flat roof last in Florida?
Typically 15 to 25 years depending on the system, installation, drainage and maintenance.
Can a flat roof be recovered instead of replaced?
Sometimes, if the insulation is dry and code allows another layer.
What is hot mop?
Another name for built-up roofing installed with hot asphalt.
About the author
Roshy Rajan has worked in Broward County real estate and construction since 2006. He founded SafeTech Roofing and Windows (SafeTech Builders Inc.) after a hurricane left a friend with roof and window damage and the referrals kept coming. Florida Certified General Contractor CGC1537934 · Certified Roofing Contractor CCC1336954 · BBB Accredited.
