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.

See our CAD images section

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 imediately on top of the flange (and the patch belneath 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.

See the CAD images here

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:

D1 is the diameter of the outlet drainage hole

D2 is the height of the (recessed) outlet drainage hole from the horizontal level

D3 is the inner diameter of the shank or outlet pipe at the bottom

L is the length of the pipe or shank

F1 is the width of the border flap or flange around the underside of the outlet hole

F2 is the height of the border flap or flange to the left and right, and above the outlet hole

F3 is the width of the flange or border flap across the face

Angled TPE corner outlet fittings

These TPE corner fittings are an alternative design to the regular corner fittings featured earlier.

They are manufactured with a 45° angle at the mouth of the outlet to help catch and direct more water into the outflow pipe off the roof. They have a square or rectangular opening at the mouth of the pipe. The flange is slightly inclined around the shank so that the outlet hole itself “juts out” away from the wall. Acting in the same way as a fillet in the junction between wall and floor, this angle pulls the water coming down the wall away from the corner and directs it into the mouth of the pipe or shank more effectively.

This corner fitting is suitable and ideal for both horizontal and vertical drains.

Although the flange is not perforated in the same way as other outlet designs, these outlet fittings are manufactured with a ribbed flange which will achieve a good bond to the bituminous roofing felt or adhesive.

We recommend a sandwich installation; so that one coat of waterproofing membrane, or one layer of felt / adhesive, is laid onto the bare concrete; the outlet is installed in place; then the second coat of adhesive / membrane is laid on top. The liquid will spread into the grooves and grip the outlet surround, also bonding to the other coat of membrane around the edges of the unit. This ensures a proper, secure fit. To improve adhesion the connector and the surrounding concrete should be prepared with a coat of primer.

They are available in two versions, with the mouth of the outflow pipe being either 65 x 100mm, or 100 x 100mm for a greater amount of water flow

The shank is 425 mm long and is capable of crossing walls of up to 40 cm. Connections can be made easily to HDPE pipework for seamless, waterproof drainage systems.

The resilient TPE material is UV stable, tough and flexible and there is no risk of becoming brittle in cold temperatures. The mechanical properties are maintained in the long term. They are compatible with APP and SBS prefabricated bituminous felts and bitumen coats.

They are measured as follows:

A is the height of the outlet drainage hole

B is the width of the outlet drainage hole

L is the inner length of the shank or outlet pipe

F1 is the width of the border flap or flange in front of the outlet hole

F2 is the height of the border flap or flange above the outlet hole

F3 is the width of the flange or border flap across the face

CAD drawings can be found in our CAD images section for these and all our roof drainage products.
See the CAD images here