Blocked or failing drains are the fastest path from a healthy roof to an interior water claim. We clear, repair, and replace internal drains and scuppers — and we address the ponding conditions that compromised them in the first place.
A commercial flat roof drain has one job: move water off the roof fast enough that ponding does not accumulate to a depth that stresses the membrane or overloads the structure. When a drain fails — through debris blockage, clamping ring corrosion, settling that breaks the bowl-to-leader connection, or simply age — it produces ponding that concentrates load at the drain location, stresses the membrane through repeated wet-dry cycling, and eventually finds its way through the assembly.
Dallas's storm intensity makes drain maintenance urgent in a way that gentler-climate cities do not experience as acutely. The National Weather Service records show that Dallas receives several rainfall events per year at intensities above two inches per hour, and events at one inch per hour are routine. A four-inch internal drain that is 30% blocked by debris cannot keep up with a two-inch-per-hour event — the roof surface fills before the drain can clear it. When the City of Dallas storm drainage system is running at capacity during a severe event, the backpressure in the storm trunk can temporarily reduce drain leader capacity below design flow. Buildings with marginal drainage are the ones that produce interior water claims on those nights.
We clean, repair, and replace drains across the full range of internal drain components used on Dallas commercial buildings. The most common internal drain manufacturers we encounter are Marathon (widely used on pre-2000 Dallas commercial construction), Zurn (the current dominant specification), and J.R. Smith (common on institutional buildings and municipal facilities). We stock replacement bowls, clamping rings, strainers, and body extensions for all three.
A drain bowl that has corroded through at the clamping ring seat — common on cast iron Marathon drains installed in the 1970s through 1990s that have been subject to standing water and chemical exposure — cannot be repaired by retightening the ring. The bowl has to come out. We core through the roofing system, extract the failed bowl, inspect the drain leader for corrosion at the connection point, install the new drain body with a compatible flashing ring, and integrate the new bowl into the membrane system with the manufacturer's specified flashing detail.
Drain leader connections are often the source of slow, intermittent leaks that look like roof leaks but originate below the roof surface. If a cast iron drain leader has separated at a hub joint, water entering the drain exits at the joint into the ceiling plenum rather than traveling to the storm system. We scope drain leaders with a camera when interior leak evidence is consistent with a drain location but the drain bowl itself looks intact.
Drain replacement on occupied Dallas commercial buildings — particularly multi-story office buildings in the Arts District and around the Reunion Tower corridor — requires temporary bypass draining while the new drain body cures into the system. We plan the production sequence around weather forecasts and temporary drainage provisions so the building is not left with a blocked drain during work.
Scuppers — the through-wall or through-parapet overflow openings that serve as secondary drainage on many Dallas commercial buildings — are chronically neglected. The primary drains get cleared; the scuppers accumulate debris, rusting metal liners, and bird nesting material for years. A scupper that cannot function as emergency overflow provides no protection when the primary drain is overwhelmed.
We clear scuppers of debris and inspect the metal liner and the exterior face of the opening. Scupper liners that have corroded or separated from the parapet face allow water to infiltrate the parapet wall assembly from behind rather than channeling it cleanly through the wall opening. We replace failed scupper liners with stainless or aluminum fabricated units sealed into the parapet wall with a backer rod and polyurethane sealant.
On buildings where scuppers serve as primary drainage (common on parapet-walled buildings without internal drains in some of the older warehouse districts along the Trinity industrial corridor), we size the scupper openings against the roof area they drain and verify they comply with the current International Plumbing Code drainage rate requirements. Undersized scuppers that were adequate for the original drainage design but have been compromised by parapet modifications are a recurrent finding on our inspection routes.
