How a built-up roof is made
- Base: insulation board or a base sheet over the deck
- Plies: usually three or four layers of fiberglass or organic felt, each set in hot asphalt or coal tar, or in a cold-applied adhesive
- Surface: a flood coat with embedded gravel, a mineral-surfaced cap sheet, or a reflective coating
The redundancy is the strength: several plies have to fail before water gets through. The 2021 IBC sets a minimum design slope for built-up roofs of 1/4 inch per foot, with 1/8 inch per foot allowed for coal-tar systems.
How BUR roofs fail
| What we find | What it means | Usual fix |
|---|---|---|
| Blisters | Trapped moisture or air between plies | Cut, dry and patch; leave sound blisters alone |
| Bare spots in the gravel | Wind and water moved the gravel; asphalt exposed to UV | Re-gravel or coat |
| Alligatored or cracked surface | Asphalt has aged and dried | Restoration coating if the plies are sound |
| Splits and ridging | Movement in the deck or insulation | Repair with new plies; check the deck |
| Leaks at walls, curbs and edges | Flashings fail before the field does | New base and counterflashings |
| Wet insulation | Long-term leaks | Replace the wet areas, or the roof if it is widespread |
We walk the roof, fly a drone for photos of areas that are hard to reach safely, and run drone thermal (infrared) scans that help show where water has gotten under the surface. We confirm with core cuts, which also show how many roofs are already on the building. Every inspection comes with a free digital photo report, so you see what we see.
Your options
- Repair: blisters, splits and flashings, when the roof is otherwise sound.
- Restore: a coating system over a dry, sound BUR, with the gravel removed or handled as the coating manufacturer requires. Asphalt-compatible products matter here. See the silicone and acrylic specs.
- Recover: a new roof over the BUR, only if code and a moisture survey allow it. Under the 2021 IBC reroofing rules, a new roof generally can't go over a water-soaked or deteriorated roof or over two or more existing layers.
- Replace: tear off to the deck and install a new multi-ply system (built-up or modified bitumen), or a single-ply TPO, PVC or EPDM roof.
Replacing BUR: which system?
| New multi-ply (BUR or mod bit) | TPO / PVC | Coating over the old BUR | |
|---|---|---|---|
| Puncture and traffic resistance | Very high | Good | Depends on the coating |
| Weight | Heavy, especially with gravel | Light | Adds little |
| Reflectivity | Low unless coated or with a white cap | High (white) | High (white) |
| Odor during install | Hot asphalt has odor; cold-applied less | Low | Low to moderate |
| Warranty | NDL available on qualifying systems | NDL available on qualifying systems | Coating system warranty by thickness |
We recommend one system for your building and explain why in writing. Compare more in the flat roof guide and read how NDL warranties work.
Older buildings: two things to check first
- How many roofs are on it. Two or more existing layers means a tear-off under the 2021 IBC.
- What's in it. Some older roofing materials can contain asbestos. On older buildings we recommend testing samples before tear-off so removal is planned and priced correctly.
Code sections and product standards are summarized in plain English from the published documents. Your building official and the manufacturer's current specification have the final word.
We're certified with GAF, CertainTeed, Owens Corning, Atlas, Johns Manville, Carlisle, Tropical Roofing Products, Mule-Hide and Enviroshake, and many other roof manufacturers. Both 10-year and 20-year manufacturer NDL (no-dollar-limit) warranties are available on commercial jobs. The price depends on which term you choose, and the manufacturer issues an NDL warranty only after its own inspection.
Commercial warranty: a workmanship warranty from 10 years up to lifetime, depending on the job, plus both 10-year and 20-year NDL (no-dollar-limit) manufacturer warranties (the price depends on which NDL term you choose). Manufacturer coverage depends on the product and brand, and on the project qualifying for that manufacturer's program. We put the exact warranty for your roof in writing.
Certified, with 30 years installing every major roofing brand, a family roofing business going back 75 years, and over $80 million in completed roofing projects. 5.0 stars on Google at all three of our offices.
Request a free inspection or call (817) 733-9228. Small repairs are welcome too.
