Wallbarn TPE Corner Roof Outlet (Perforated Flange)

Wallbarn TPE Corner Roof Outlet (Perforated Flange)

Wallbarn supplies a pre-cast corner fitting for drainage holes on roofs, balconies and terraces which is situated between the horizontal deck and the parapet wall or upstand. Contractors need to be sure that the area around these holes, which will have to contend with a great deal of water run-off, is completely waterproofed and protected from puncture damage and stresses caused by building movement.

The drainage outlet connector (1) is designed to be sandwiched between two layers of bituminous membrane (2) using the perforated flange design for the over-and-under secure bond.

They ensure that the area is completely waterproofed around and into the drain pipe, so that there is no risk of water creeping behind the drainage hole and causing a leak.

The manner they are fitted is described in this example:

The outlet was installed into the drainage hole over an existing layer of bituminous felt in this instance, where a new bituminous membrane was being installed on top of insulation. A patch of felt was installed (right) on top of the existing membrane and torch bonded to it. It is important that the bitumen on the top of this patch is exposed. The upper side of the patch was also torch-heated so that the bitumen became tacky on the upper side.

The outlet was then placed on top of the patch when the bitumen was still tacky and pressed into it firmly. Some of the bitumen oozed through the perforations.

A second layer of felt was installed immediately on top of the flange (and the patch beneath it) whilst the bitumen was still tacky and again was torch-heated so that the bitumen on this upper layer also liquified slightly.

This means that the two layers of felt bonded to each other around the edge but also through the holes in the flange of the outlet, giving an extremely strong “over-and-under” bond.

The entire roof deck and the upstand was finished with a layer of torch-on felt whichhad been laid over the outlet. The area around the outlet hole was dressed with the felt membrane so that the whole area was sealed and the roof had a suitable fall into the drainage hole.

The spigot pipe is round and slightly recessed, with a small drop form the horizontal border flap to encourage the water to flow into the pipe immediately and not pond around the mouth of the pipe and possibly creeping back behind the outlet.
The pipe or shank is slightly angled down to create a “fall”, encouraging faster flow of the water down the pipe. The shank is 500mm long, so it can cross through 45cm of wall before having to be connected up.

The TPE connector is extremely tough, and resistant to UV deterioration and chemical salts.

They can be fitted to vertical downpipes at the edge of the retaining wall, or on a horizontal plane through the upstand or wall to then connect to the external downpipe.

They are measured as follows: