Stainless Steel Inside Wall Parapet Roof Drain with Overflow

Thunderbird's 316 stainless steel inside wall parapet roof drain with overflow gives you a primary drain and a backup in one unit. The overflow kicks in when water depth hits a level that says your primary outlet is either clogged or overwhelmed — it routes excess water through a secondary path before ponding becomes a structural load problem. If you've ever gotten a callback because six inches of standing water turned a flat roof into a swimming pool, this is the product that prevents that conversation. Features: 316 Stainless Steel Construction: Marine-grade stainless that handles salt air, chemical exposure, and years of freeze-thaw without pitting or corroding. Won't stain your facade the way copper does over time. Sandblasted Flashing: Roughened surface profile bonds tight to waterproofing membranes. Lap your membrane over the flange and you've got a watertight connection — no sealant dependency. Built-in Overflow: Secondary drainage outlet mounted higher on the body. Sits dormant during normal rain and activates automatically when water reaches a depth that means the primary can't keep up. No moving parts, nothing to maintain. Multiple Outlet Sizes: 2", 3", and 4" to match your leader pipe. Size the primary to your calculated roof load; the overflow handles the margin. Made in the USA: Built and shipped domestically. Also available in TPO Clad and PVC Clad for direct heat-welding to single-ply membranes, or without the overflow if your primary system has enough redundancy on its own. Applications: Parapet Wall Drainage: Flat roofs with parapet walls where you want both primary drainage and overflow protection in a single penetration. The inside-wall outlet keeps plumbing internal — no exposed pipe on the building exterior. Spec this over the standard unit on larger roof areas, low-slope assemblies, or any job where the owner wants belt-and-suspenders peace of mind against heavy storm events. Same drain as the standard parapet unit, with the overflow built in so you're not cutting a second hole in the wall later when someone decides they want one. Pick your outlet size, match the flange to your membrane system, and you're covered for the worst rain the roof will ever see.