Epoxy roof drain lining in Denver, Colorado

What a roof drain system is and why it fails

Epoxy roof drain lining in Denver, Colorado deals with a pipe most building owners never think about until it stains a ceiling tile. A flat commercial roof drains through bowls set into the deck, each feeding a vertical leader, often cast iron in older buildings, that drops through the floors, turns horizontal above the lowest ceiling or below the slab, and joins the storm sewer. The leader carries rainwater only: empty most of the year, full during a storm, empty again. That cycle is what kills it. Lead and oakum hub joints open as the pipe expands and contracts with roof temperature, the wall rusts in a ring at every hub where water lingers, and ponding loads the bowl and first joint for days. When the leader leaks, it leaks inside a wall or above a finished ceiling, floors below the actual defect.

Why replacement is so disruptive in an occupied building

Cutting out a vertical leader means opening the chase on every floor it passes, working over tenants, and closing everything up again, often around electrical and data sharing the chase. On a multi-story building the ceilings, paint and lost occupancy outweigh the pipe. Lining reverses that: the liner enters through the roof bowl and the whole run is rehabilitated from the top, with the crew staging on the roof and at the base cleanout rather than in the offices between.

Lining a vertical pipe from the roof down

The sequence differs from a horizontal lateral. Gravity helps the liner in and works against the resin afterward, so the process is built around holding the liner in place while it cures.

• Inspect and measure. A camera is lowered from the bowl and the run is recorded, with every hub, offset and the base turn logged by depth.
• Descale. Cast iron leaders carry heavy tuberculation. A chain flail run from the top removes it, followed by jetting and a second camera run to confirm a sound wall.
• Remove the bowl. The roof drain bowl and clamping ring are lifted so the liner can enter the leader straight.
• Invert or pull. A felt tube wet out with epoxy is inverted downward with air pressure or pulled down with a bladder inside. The bladder is inflated to press the liner against the wall and stays inflated through the entire cure.
• Cure. Epoxy is chosen for leaders because it bonds to descaled iron, produces low odor in a building full of people and cures at ambient temperature or with warm water circulated through the bladder. Temperature is checked at the base, where a vertical run is coldest.
• Finish the ends. The top is trimmed flush and the bowl reset with new flashing. The bottom is cut back at the base cleanout or the first horizontal fitting and the camera records the finished run.

An explanation of epoxy roof drain lining in Denver shows the bladder and inversion head in use, which makes the sequence easier to follow from the roof.

Offsets, overflow scuppers and the base turn

Few leaders drop in a straight line. An offset where the pipe steps around a beam is common, and a felt liner will negotiate a pair of forty-five degree bends once descaling has removed the ledge at each hub. Two tight ninety-degree bends may call for two shorter liners meeting at the offset, or a sectional repair at the bend with full liners above and below. Overflow scuppers are a separate system and are not lined, but where a secondary drain ties into the primary leader below the roof, that connection is reinstated with a robotic cutter after the cure, as a branch would be on a horizontal lateral. The base turn is the most damaged point in the system, because debris collects there and the elbow wears from inside. The liner should run through that turn into the horizontal pipe, never stop above it.

Working without disturbing finished ceilings

The crew needs the roof, the base cleanout or lowest chase, and a stairwell for hoses and camera cable between them. No water is shut off, because the drain carries only rain, and the occupant impact is descaling noise and a mild epoxy odor near the base for a few hours. A dry forecast matters more than any other factor; a storm during the cure fills a bladder-blocked leader and the scupper has to carry the roof. Property managers comparing how vertical drain stacks are lined from above across a portfolio of flat-roofed buildings in Denver usually find leaders a better candidate than the storm laterals under the parking lot, because the access saved is inside the building. The crew should show its certification on the epoxy system proposed and its record on vertical work, and verified CIPP installers serving Denver is where to confirm both before the bowl comes off.

What the report should contain

Ask for the pre-lining video by depth with each hub and offset noted, the post-cleaning video, liner and resin data sheets naming the ASTM F1216 or F1743 basis, a cure log with temperatures at top and base, post-lining video showing the bowl connection, any reinstated secondary drain and the base turn, and a roof plan marking which leaders were lined. Colorado jurisdictions generally regulate storm drainage under the plumbing code, and a permit and inspection may be required in Denver, so the report should include the permit number where one was pulled.

Common questions in Denver