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C.06 · Commercial roofing

Built-up roofing in Tulsa.

Built-up roofing has been on Oklahoma commercial buildings since before single-ply membranes existed. Multiple plies of reinforced felt and hot asphalt, topped with gravel ballast. Thick. Redundant. Proven. Still the right call for certain buildings, and still something we install when the job calls for it.

3 and 4 ply systemsHot-mop or cold-appliedGravel or smooth surface20-30 year lifespan

Q: What is built-up roofing (BUR) and when is it still the right system?

A: Built-up roofing (BUR) is a multi-ply system of alternating layers of bitumen and reinforcing felt, finished with a flood coat of asphalt and embedded gravel. It has been used on flat commercial roofs for over 100 years. BUR remains the right choice for industrial and chemical facilities with specific compatibility requirements, buildings where an engineer specifies multi-ply redundancy, and applications where existing BUR is being repaired or replaced in kind. For most new commercial construction, modified bitumen or single-ply membranes are now the modern equivalent.

There are still a lot of built-up roofs on Tulsa commercial buildings. Older warehouses, industrial facilities, schools, and retail centers built before 1990 often have two, three, or four-ply BUR systems that were installed when that was the commercial roofing standard. Some of those roofs are still performing well. Others are at the end of their service life and need either repair or replacement.

We handle both. For BUR systems that are structurally sound but showing localized failure, repairs using flood coat and aggregate extension can extend life several more years. For systems past their service life, we evaluate whether a modified bitumen cover system can be installed over the existing plies, or whether full tear-off and replacement with a current system is the better path.

We also install new BUR systems when the project calls for it. Certain industrial applications, chemical facilities, and engineer-specified projects require the multi-ply redundancy and chemical resistance that BUR provides. If your project specifies BUR, we have the equipment and the crew to install it correctly.

BUR condition indicators

Signs your BUR roof needs attention.

BUR systems fail differently than single-ply membranes. These are the specific signs to watch for.
01

Alligatoring on the flood coat

Surface cracking that looks like alligator skin means the asphalt flood coat has dried and oxidized. It no longer protects the plies below from UV. Repair or re-coat before water works through.

02

Gravel displacement

Gravel that has washed to the drains or is piled unevenly leaves portions of the flood coat exposed to direct UV. Redistributing gravel is a maintenance item; ignoring it accelerates coating degradation.

03

Blistering between plies

Blisters on BUR indicate moisture or vapor trapped between plies during installation or from a long-term slow leak. Large blisters and extensive blistering indicate deeper insulation saturation.

04

Flashing separation at walls

BUR flashings at parapet walls and curbs are often the first failure point. Felt plies shrink and pull away. Re-flashing with a modified bitumen cap sheet is a common repair.

05

Active interior leaks after rain

BUR leaks often present far from the actual entry point due to water migrating between plies. An active leak inside the building needs immediate diagnosis, not a patch at the interior stain.

06

System past 20-25 years

BUR systems past 20 years are approaching end-of-life in Oklahoma conditions. Proactive replacement planning avoids the emergency scenario of a major storm finding an aged roof at its worst.

Our BUR process

Four steps for repair or new installation.

Whether we are repairing an existing BUR or installing new, the sequence is the same.

01/04

Inspect and core-cut

We walk the entire roof, photograph deficiencies, and pull core samples to count plies, check insulation condition, and assess substrate moisture. BUR core cuts also tell us how the existing plies are adhered and whether a recover is feasible.

Free / same week
02/04

Scope: repair vs. replace

Based on core cuts and inspection findings, we give you a clear recommendation: repair, cover system, or full replacement. For BUR specifically, a modified bitumen cover can often extend life 15 to 20 years over existing sound plies without tear-off. We show you both numbers.

Clear recommendation
03/04

Install or repair

New BUR installs use asphalt kettles, experienced hot-mop crew, and controlled application temperatures. BUR repairs use flood coat and aggregate extension at failure areas. Modified bitumen covers use torch or cold-applied cap sheet over prepared substrate.

Crew-supervised
04/04

Document and maintain

Written close-out documentation, material specs, and photos. For ongoing BUR maintenance, our bi-annual program includes gravel redistribution, drain clearing, and flashing audits, the items that matter most for BUR longevity.

Documented close-out
BUR system components

Plies, bitumen, and surface options.

A built-up roof consists of three main components: the base sheet or vapor barrier, the reinforcing plies in hot asphalt, and the surface treatment. The ply count, bitumen type, and surface finish are specified based on building use, foot traffic, and local wind and hail exposure.

Three-ply BUR is the standard commercial specification. Three layers of reinforcing felt in Type III or Type IV asphalt provide adequate waterproofing for most commercial flat roofs. The flood coat and gravel finish protects the plies from UV and provides fire resistance.

Four-ply BUR is specified for high-traffic roofs, industrial applications, and buildings with chemical resistance requirements. The additional ply adds puncture resistance and redundancy. It is heavier and costs more, but for the right application it is the correct specification.

Smooth-surface BUR uses an aluminum coating or cap sheet instead of gravel. It is lighter, easier to inspect, and better suited for sloped-to-drain applications. Used on some retail and light commercial buildings where gravel ballast adds unnecessary load.

Cost considerations

What drives BUR cost.

BUR costs more to install than most single-ply membranes because it requires more materials, more labor time, and specialized equipment. Hot-mop application requires asphalt kettles, temperature control, and a larger crew than single-ply installation. Those costs are real and show up in every honest BUR bid.

For buildings where BUR is being replaced with a modern system, the tear-off cost can be significant. BUR roofs are heavy. Multiple plies of asphalt-saturated felt and gravel ballast can add up to several pounds per square foot of material to remove. Disposal costs are higher than single-ply tear-off.

The most cost-effective option for many aging BUR roofs is a modified bitumen cover system over the existing plies, if core cuts show sound underlying construction. This avoids tear-off entirely and can extend roof life 15 to 20 years. We will give you both numbers at the bid stage so you can make the right call for your building.

BUR on your building? Get it assessed.

(918) 978-2660Talk to a commercial project managerRequest a commercial bid
Why AE Roofing for BUR

Fewer people know how to do this right.

Hot-mop BUR is a skilled trade. Asphalt application temperature, ply interleaving, drainage slope, and flood coat depth all have to be right. Most newer commercial roofing crews have never run a kettle. The market has moved to single-ply, which means BUR experience has narrowed to contractors who have been doing it for a long time.

We have that experience. Our crew has installed and repaired BUR on Tulsa commercial buildings including industrial facilities, schools, and older retail centers where the original system is still worth maintaining. We also know when to stop repairing and when to recommend a modern replacement that will serve the building better over the next 20 years.

BUR roofs that are well-maintained last a long time. Our bi-annual maintenance program includes the specific tasks that BUR systems need: gravel redistribution, drain clearing, and flashing audits. For multi-property owners, our asset management program tracks condition across all buildings on a single report.

Service area

We install and repair BUR across Tulsa and these surrounding cities:

Broken ArrowCoverage
OwassoCoverage
BixbyCoverage
JenksCoverage
Sand SpringsCoverage
SapulpaCoverage
ClaremoreCoverage
CatoosaCoverage
Built-up roofing FAQ

Questions about
your BUR roof.

Not on the list? Call us. A human picks up. Usually on the second ring.

Ask us directly
A properly installed BUR system with three or four plies and gravel ballast lasts 20 to 30 years in Oklahoma conditions. The thick multi-ply construction handles hail better than most single-ply membranes. Key variables are drainage quality, regular maintenance to keep gravel in place, and whether the flashings are maintained over time.
BUR is less commonly specified on new commercial construction than it was 30 years ago. Single-ply membranes and modified bitumen are generally faster to install and carry better warranty terms from manufacturers. That said, BUR remains the right specification for some industrial, chemical, or high-traffic applications, and for buildings where an architect or engineer specifies it. We install it when it is the right system for the job.
Built-up roofing uses alternating layers of reinforcing felt and hot asphalt, topped with a flood coat and gravel. Modified bitumen is a factory-modified cap sheet applied over a base sheet. BUR has more plies and uses loose gravel ballast. Modified bitumen is faster to install and carries more predictable factory warranties. For new builds replacing aging BUR, modified bitumen is often the modern equivalent.
Yes, if the existing plies are sound and the insulation is dry. BUR repairs use flood coat and aggregate at failure areas. We can also apply a modified bitumen cap sheet over an existing BUR system as a cost-effective upgrade. Core cuts at the inspection tell us which option makes sense for your building.
Yes. Hot-mop BUR requires asphalt kettles, mop carts, and experienced crew members who know how to control asphalt temperature and application rate. Cold-applied BUR avoids the kettle but requires adhesive management and weather-appropriate conditions. We have the equipment and the crew for both methods.
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