Chimney, Duct & Exhaust Stack Waterproofing for Metal Roofs in Saudi Arabia

Why leaks start around chimneys and ducts

A stack passing through a metal roof is attacked from three directions at once. The flue or duct runs hot, the fan or process equipment makes it vibrate, and its outline rarely matches the profile of the sheeting around it. Sealant beads and cut-to-fit metal collars are rigid, so after a few summers of heating, cooling and shaking they crack or pull away, leaving a gap exactly where rain collects.

In the Eastern Province the problem is made worse by humid, salty air. Water that sits around the base of a duct in Dammam, Jubail or Al Khobar turns into rust on the upstand and the surrounding sheets, and every Shamal-driven shower pushes more water sideways into the opening. Sealing the joint properly also stops that standing water, so it protects the steel as well as the building below.

Warning signs at your roof penetrations

• Drips or stains on the ceiling or insulation around a flue, extractor or duct
• Cracked, hardened or missing sealant at the base of the stack
• Rust streaks on the upstand or the roof sheets next to it
• Water pooling on the uphill side of a wide duct after rain
• A metal collar that has been re-sealed several times and still leaks
• Loose or rattling flashing around vibrating exhaust fans

How ETCE seals a chimney or duct penetration

1. Survey and heat checkOur engineer inspects each stack, notes its shape and operating temperature, and records it with photos in the written survey report.
2. Strip and cleanFailed sealant, loose collars and debris are removed, and the steel around the opening is cleaned back so the adhesive bonds to a sound surface.
3. Cut EPDM to the shape1.2 mm EPDM is cut to suit the stack and the roof profile around it, whether the duct is round, square or irregular.
4. Wrap all four sidesThe membrane is bonded with Promax Bonding Adhesive up the stack and out onto the sheeting on every side, leaving no gap for water to enter or stand.
5. Final inspectionEach wrapped penetration is checked for full adhesion and photographed before the zone is handed back.

Materials & workmanship

• 1.2 mm EPDM membrane that stays flexible under vibration and UV exposure
• Promax Bonding Adhesive, rated for surface temperatures up to 120 °C
• Stacks running hotter than 120 °C receive a newly fabricated flashing instead
• Up to 15-year warranty on the EPDM system, with a 24–48 hour after-sales response

Photos from ETCE projects

Site photos from ETCE projects in Saudi Arabia and Bahrain. Tap to enlarge.

Frequently asked questions