OATEY 78036 6" PVC Roof Drain w/ ABS Dome & Dam Collar

The 78036 is a 6 inch PVC roof drain, so it drops into a 6 inch PVC drain line. The body is PVC, which means it solvent welds to PVC pipe rather than threading or clamping. If your roof leader is ABS or cast iron, you need either a matching ABS body drain or a transition coupling at the connection.

The ABS dome strainer is included, and so is the dam collar. The dome keeps leaves and debris out of the leader; the dam collar is the ring that holds water back so the drain functions as a controlled or secondary overflow point. You are not buying those as add-ons.

On the 78036, the dam collar sits around the drain body and ponds water to a set depth before it can enter the drain. Roofers use that on secondary or emergency drains, where the code intent is that the primary drain carries normal flow and the dammed drain only takes over when the primary backs up or the roof loads with water. If you are specifying the primary drain on the roof, you generally do not want the collar installed.

Take care there. The body is PVC and the dome is ABS, both thermoplastics, so direct flame or hot asphalt against the drain is not something the material tolerates the way a cast iron drain does. PVC drains are normally set on single-ply, modified bitumen with cold adhesive, or coated membranes. For torch work or hot kettle asphalt right at the sump, specify a cast iron drain instead.

78036 is the complete assembly, not a dome on its own. You get the 6 inch PVC drain body plus the ABS dome and the dam collar. If all you need is a strainer, ordering this part number means paying for a full drain.

Yes, that is what it is built for. It is a roof drain, meaning it sets in a sump in the low point of a low-slope roof, the membrane is flashed into the drain, and the 6 inch PVC outlet runs down through the deck into the leader. It is not a deck drain or a scupper, and it is not intended for a sloped shingle roof.

Most low-slope roofs are drained in pairs: a primary drain at the low point and a secondary or overflow drain nearby, set higher so it only runs if the primary plugs. The 78036 covers both cases because it ships with the dam collar, install the collar and it serves as the dammed secondary, leave it off and it serves as the primary. Buying two of the same part number for one roof sump is common practice.

It weighs 5.8 pounds complete, which is why crews pick a PVC body over cast iron for reroof and retrofit work. One person can carry several up a ladder, and the deck does not need the extra support a cast iron drain and its clamping ring would call for.