Roofing types · Built-Up Roofing (BUR)
Built-up roofing: the original — and still hard to kill.
BUR — tar and gravel — is the oldest low-slope system in America, and buildings are still dry under 40-year-old installations. Managing one well comes down to knowing what’s under the aggregate — which takes the right instruments, honestly applied.
Schedule My Free Roof Assessment01 · The system
What built-up roofing is — and how it works.
Built-up roofing is alternating layers of asphalt and reinforcing felts — three, four, five plies — topped with a flood coat and gravel. The redundancy is the point: a puncture has to defeat every ply before your deck sees water.
The gravel that protects it also hides it. Surface inspection tells you little, and aggregate scatters the infrared signal — so on BUR we say plainly what most won’t: parts of this system need impedance scanning, test cuts, and core sampling to map honestly. We bring all three.
System profile
- Membrane
- Asphalt + felt plies (3–5)
- Seams
- Continuous mopped plies
- Attachment
- Hot asphalt, mopped
- Typical service life
- 20–30 years
- Surface
- Flood coat + aggregate / smooth
- Infrared candidacy
- Limited under aggregate — impedance/coring instead
02 · Straight talk
Where built-up roofing excels — and what to watch.
Where it excels
Deep redundancy
Multiple continuous plies; single-point damage almost never reaches the deck.
Ballast protection
Gravel armor shrugs off UV, hail, and foot traffic that would score a membrane.
Long, slow aging
BUR fails gradually and repairably — rarely catastrophically.
Repair heritage
Every commercial roofer’s grandfather fixed BUR; the methods are proven and materials available.
What to watch
Hidden moisture
Aggregate masks both visual and infrared inspection; unmanaged BUR can hide years of saturation.
Blistering and alligatoring
Exposed flood coat cracks with age; blisters mark inter-ply moisture or gassing.
Weight
BUR is heavy, and wet BUR is much heavier — a structural consideration on marginal decks.
Flashing age
The plies outlive the flashings; most BUR leaks are detail failures, not field failures.
On BUR we lead with the limitation: infrared alone can’t map it honestly — so we don’t pretend it can. Impedance scanning and core verification do the job instead.
03 · The lifecycle
How we manage built-up roofing — from baseline to replacement.
A combined survey — impedance scanning, test cuts, and cores — maps moisture under the aggregate; smooth-surfaced BUR sections get infrared too.
LionCare keeps drains clear (gravel loves to migrate into them) and watches flashings — where most BUR leaks actually start.
Mopped or cold-process patches by crews who know asphalt systems — diagnosed first, always.
Dry, sound BUR takes aluminized and reinforced restoration coatings — a common 10-year extension on smooth-surfaced sections.
When cores say saturation, replacement is scoped from evidence — including a structural look at what the wet assembly weighs.
04 · Questions
Frequently asked questions.
What owners ask about built-up roofing roofs.
Can you infrared-scan a tar and gravel roof?
Only partially, and we’d rather be straight about it: aggregate scatters the thermal signal. Smooth-surfaced BUR scans acceptably; graveled sections get impedance scanning and core verification instead. The map is just as definitive — the instrument is different.
My BUR roof is 30 years old. Is it done?
Not necessarily. BUR age matters less than moisture content and flashing condition — we’ve mapped 35-year-old assemblies that were bone dry, and 12-year-old ones that weren’t. Cores tell the truth.
Is the weight of BUR a problem?
Dry BUR was engineered into the original structure. The risk is wet BUR — saturated insulation and plies add real load. That’s a measurement question, and it’s part of any honest BUR assessment.
Evidence first
Own a tar & gravel roof? Find out what’s under the gravel.
Impedance, test cuts, and cores turn the most opaque roof system into a documented, quantified plan.
Schedule My Free Roof Assessment651-780-7663 · info@lionstarcommercialroofing.com