Roof Drains Scuppers in Houston, TX

Roof Drains and Scuppers for Houston Commercial Buildings
A low-slope commercial roof is only as good as its ability to get water off itself, and on the Gulf Coast that is the part most often overlooked until a ceiling tile gives way. We design, install, repair, and retrofit the full drainage system on flat and low-slope roofs across the metro: interior roof drains, through-wall scuppers, overflow provisions, and the leaders and conductor piping that carry water away. When drainage is right, the membrane above it lasts the way it was supposed to. When it is wrong, even a brand-new roof starts failing from standing water within a few seasons.
Why Drainage Is the Weak Point Here
This region absorbs some of the heaviest rainfall in the country, and it arrives in short, violent bursts rather than steady drizzle. A summer thunderstorm can drop several inches in an hour, and a tropical system can dump far more. When Hurricane Harvey stalled over the area in 2017, the volume of water that landed on rooftops exposed undersized and clogged drainage on commercial buildings all over town, and ponding that should have cleared in minutes instead sat for days and found every weak seam. Drainage that was specified decades ago, for rainfall assumptions that no longer hold, is one of the most common problems we find on older roofs across the metro.
Standing water is not a cosmetic issue. A roof was engineered to shed water, not store it. An inch of ponded water weighs better than five pounds per square foot, and a wide pond adds load the structure was never meant to carry. Trapped water also accelerates membrane aging, breaks down adhesives and seams, and in our long, hot cooling season it bakes and grows algae between storms. Get the water moving and most of those problems never start.
What a Complete Roof Drainage System Includes
Drainage is a system, not a single fixture, and each part has to be sized and detailed to work with the others:
Primary roof drains: The interior drains set at the low points of the roof field, fitted with strainer domes and clamped tightly into the membrane to carry the bulk of the water into internal conductor piping.
Scuppers: Through-wall openings at the perimeter parapet that let water escape over or through the wall, often the simplest and most reliable path on buildings with parapets and exterior leaders.

Roof planning guidance

Overflow drainage: A required secondary path, either overflow drains set slightly above the primaries or overflow scuppers cut above the design water line, that opens up if the primary system clogs or is overwhelmed. Tapered insulation and crickets: Built-up slope in the insulation layer that steers water toward the drains and breaks up the dead-flat areas where ponds form behind curbs and equipment. Leaders and conductor piping: The internal or external piping that moves the collected water down and away from the building to the storm system.

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Overflow Drainage Is Not Negotiable

The single most important safety feature on a flat roof is the one that only does its job on the worst day. Overflow drainage exists for the moment a primary drain chokes on debris during a downpour, and it has to be there before that moment arrives. We see buildings where the overflow scuppers were never cut, or where someone sealed over the old overflow drains during a re-roof. On a parapet-walled roof with no working overflow, a clogged primary drain turns the roof into a shallow pool with nowhere to go, and the water climbs until something fails, usually the roof deck or the wall flashing. Every drainage retrofit we do confirms that a real secondary path exists and is set at the right height above the primary line.

Sizing for Real Houston Rainfall and County Rules

Houston Energy Corridor commercial buildings

Drains and scuppers have to be sized to the rainfall intensity this area actually produces, not to a generic national default. We size primary and overflow capacity to local design storm rates and to the area of roof each drain serves, so the system clears a hard Gulf Coast rain instead of backing up at the strainer. Drainage work here also lands in the middle of Harris County Flood Control District expectations, and on many sites the rate and volume of stormwater leaving the roof ties into detention and site drainage requirements that tightened after Harvey. We coordinate the roof side of that so what leaves the roof is sized correctly and connects cleanly to the site system rather than overwhelming it.

Common Drainage Failures We Correct

Most drainage calls trace back to a short list of recurring problems, and each has a real fix:

Roof planning notes

Roof Scope Notes

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Drains set too high: Drains mounted above the surrounding roof plane leave a permanent puddle; we reset them into a proper sump.

Ponding from inadequate slope: Dead-flat fields that never drain get tapered insulation and crickets to move water to the drains. Failed drain-to-membrane seals: The flashing where the drain meets the roof is a classic leak point; we rebuild it with the correct clamping ring and target sheet.

Where This Work Matters Across the Metro

Missing or sealed-over overflows: We cut or restore the secondary drainage path the roof is required to have. Talk with a Houston commercial roofing team