Best Practice in Managing Membrane Roof Penetrations

In the perfect world of waterproofing, no roofs would have any penetrations…but we don’t live in a perfect world. Roofs need to accommodate aerials, pipes, solar panels and the like. Poorly detailed roof penetrations can lead to water ingress. Membrane roofs have lower slopes than pitched roofs, so theoretically should be more susceptible to leaks. But fortunately, membrane roofing has evolved a long way in this regard, thanks to the development of a series of clever accessories for penetration detailing. Having said this, the compatibility of the accessory and the roofing material for the duration of the roof’s warranty period and beyond is important to Viking Roofspec who will only distribute its materials as a tested ‘system’.

Below is a list of accessories distributed by Viking Roofspec which manage penetrations beautifully:

Solar Panel and Air Conditioning Unit Mounts

An EJOT bar is a length of aluminium box-section encased in TPO (thermoplastic roofing material) including a TPO flange which heat-welds onto a TPO membrane roof; In Viking’s case – an Enviroclad TPO membrane roof. This allows solar panels and other forms of plant to be fastened to the roof without penetrating the membrane, simply by screwing into the box section with an appropriate self-tapping fastener. The wind uplift resistance of each length is up to 2.7 kilonewtons and of course, the overall resistance of the ‘system’ improves with a greater frequency of bars installed as the load becomes increasingly shared.

Evo Solar Mounts
The principle of this extruded aluminium system is similar to the EJOT bar except it has been developed specifically for torch-on membrane systems and the extrusion has a channel into which the solar panel stands are secured.

Acoustic Mount Blocks
This Kiwi-made item is a treated timber block, waterproofed with factory-applied shredded rubber. An aluminium channel on the surface serves a similar purpose to the channel of the Evo system, accommodating the feet of various forms of plant. Acoustic mount blocks can sit on any membrane type and are perfect for supporting very heavy plant such as air conditioning units. For very high wind zones, a specific fastening detail would be required, otherwise, these blocks just sit on the membrane.

General Penetration Detailing

Pourable Pockets
A pourable pocket provides an effective way of detailing around roof penetrations. In the case of the Enviroclad TPO membrane pourable pocket, it’s simply a proprietary TPO upstand which surrounds the penetration(s) and its flange is heat-welded onto the Enviroclad membrane. Then a specially-formulated rubberised sealant is poured into the surround; thus sealing around the penetration(s) whilst also providing 50mm of contingency above the critical junction.

Pipe Seals
A pipe-seal is a proprietary TPO-weldable flashing shaped like a witch’s hat with a series of diameters to which it can be cut to suit the pipe size. Like the above-mentioned pourable pocket, it also has a flange which is welded to the Enviroclad membrane. The top of the flashing is also waterproofed with sealant and a hose-clamp.

So, to conclude, a waterproofing membrane doesn’t simply leak in the middle of the sheet unless it has been penetrated. It’s therefore left to the skill and care of the installer to ensure that the penetration is sealed and that it will remain watertight for the duration of the warranty period and beyond. But these days, a lot of the risk of water ingress is minimised via the correct application of proprietary (and compatible) accessories to keep water out of the building for good.