A ballasted roof holds its membrane down with stone or pavers rather than fasteners or adhesive, and it still covers many older Raleigh commercial and industrial buildings across the Triangle.
We assess and repair ballasted assemblies with an eye on their two defining traits: the membrane is hidden under the ballast, and the building has to carry the weight.
How Ballasted Roofs Are Built and Where They Fit
In a ballasted system the membrane is laid loose over the insulation and held in place by a layer of smooth stone or concrete pavers. Because nothing penetrates the membrane to attach it, there are very few fastener leak paths, and the ballast shields the membrane from UV, which historically gave these roofs a long, low-cost service life. Much of the Triangle's older low-slope inventory carries this system.
The Trade-offs on Triangle Buildings
The ballast that protects the membrane is also the system's complication. It adds significant dead load, so the structure must be designed to carry it, and it hides the membrane, which makes leaks hard to locate because the water entry point and the interior stain can be far apart under the stone. At the perimeter and corners, where Raleigh's storm winds are strongest, ballast can be scoured away and expose the membrane to uplift. Inspecting and repairing these roofs means moving stone to read the membrane underneath.
What We Document Before Repair or Replacement
Our assessment of a ballasted roof pulls back ballast at suspect zones to inspect the membrane and seams directly, checks the perimeter for scour and uplift exposure, and cores to confirm the insulation is dry. Because these systems are labor-intensive to open and the structural load limits the options, the scope is honest about whether targeted repair under the ballast is realistic or whether the roof has reached the point for replacement with a lighter, more inspectable system.
Frequently asked questions
Why are leaks hard to find on a ballasted roof?
The membrane sits hidden under stone, so water can enter at one point and surface inside the building far away. Finding the source means moving ballast to inspect the membrane directly.
Can a ballasted roof handle Raleigh's storm winds?
The field is generally stable, but the perimeter and corners are vulnerable: high winds can scour the ballast and expose the membrane to uplift. Those edges are the focus of our inspection.
Should an old ballasted roof be replaced with the same system?
Often a lighter, fully visible system makes more sense at replacement. It removes the structural load and the buried-membrane problem, making future inspection and repair far easier.
