Some of the manufacturing buildings and older industrial structures we work on around Macon were built for a gravel-surfaced built-up roof from the start, with structural framing sized for that load. We still spec BUR on those buildings rather than forcing a lighter system onto a deck designed for it.
A built-up roof alternates layers of asphalt or coal-tar pitch with reinforcing felt, typically three or four plies, finished with a gravel or mineral cap sheet. Each ply adds waterproofing redundancy, which is why BUR has stayed in use on industrial and manufacturing buildings even as single-ply membranes have taken over most new construction.
The gravel surface also protects the underlying plies from UV degradation and adds a measure of fire resistance and impact protection that a bare membrane doesn't offer, which matters on plants with rooftop equipment maintenance traffic or occasional hot work nearby. On older facilities, we still find BUR installations from decades ago performing acceptably with only minor flashing repairs, which speaks to the system's durability when it's installed and maintained correctly from the start.
Gravel-surfaced BUR is heavy, typically ten pounds per square foot or more, and that load has to be accounted for in the structural design. For a building already engineered around that weight, and plenty of the older manufacturing stock around Macon was, BUR remains a sound, cost-effective choice rather than a legacy system we're trying to talk owners out of.
For newer construction or buildings where the structural budget doesn't allow for the added dead load, we typically steer owners toward TPO or modified bitumen instead, which deliver comparable durability at a fraction of the weight.
The multi-ply, gravel-surfaced assembly holds up well against the wind-driven hail that comes through with Middle Georgia's severe thunderstorm season. The gravel layer absorbs some impact energy before it reaches the waterproofing plies underneath, which is one reason BUR has stayed a durable option on industrial roofs in this climate.
After a significant storm, we walk the roof to check for gravel displacement, exposed felt, and blistering, documenting any damage for the owner's maintenance record or insurance claim.
A lot of our BUR work isn't new construction, it's reroofing or recovering a system that's been patched for twenty or thirty years. We evaluate whether the existing deck and insulation still perform well enough to support a recover ply, or whether moisture has worked into the insulation to the point that full tear-off is the only responsible option.
Built-up roofs need periodic gravel redistribution where foot traffic or wind has thinned the surface layer over drains and low areas, and we check flashing at parapets and curbs on the same schedule, since that's where most BUR leaks originate rather than in the field of the roof itself.
We also watch for blistering, which shows up as raised bubbles in the felt layers from trapped moisture or air, and address it before it develops into a full leak path.
Plant roofs tend to accumulate rooftop equipment over the years: added exhaust fans, secondary HVAC units, conduit racks, and platform walkways for maintenance access. Every addition changes the load and the penetration count on a BUR system that was designed for a simpler original layout, and we account for that accumulated load before recommending a recover ply on an older roof.
We also flag where equipment curbs have been added without proper cricket or saddle flashing to divert water around them, a common source of ponding and eventual leaks on older industrial roofs we're asked to inspect.
On some of the older manufacturing buildings we've serviced west of downtown, the original 1960s or 1970s BUR is still partially intact under two or three later recover layers, and untangling that history is part of the moisture-survey work before we can recommend anything with confidence. Sorting that history out properly the first time saves an owner from paying for a recover assembly over a hidden problem later.
For buildings engineered to carry the additional weight and where owners want a proven, multi-ply system, yes. For most new construction, we more often recommend TPO or modified bitumen for the lighter load.
Service life varies with ply count, materials, and maintenance history. We evaluate condition on a case-by-case basis rather than quoting a blanket number.
Sometimes, if the deck and insulation pass a moisture survey. We'll core-sample the existing roof before recommending recover over full replacement.
It can if drains aren't maintained. We include drain strainer inspection and gravel-guard checks as part of our recommended maintenance schedule.
The gravel or mineral surface adds a degree of fire and impact resistance that a bare single-ply membrane doesn't offer on its own, which is one reason it stays specified on certain industrial occupancies.
