Roof Leaks on Commercial Buildings – Part 2

Roof leaks on commercial buildings can often be sourced to poorly installed air conditioning units. In Part 1 of this series we demonstrated how roof leaks on commercial buildings can be caused by too many ac unit pipes running through one penetration. In addition, we showed how roof leaks can also be caused by the ac unit being positioned on treated pine timber struts.

Air Conditioning Flashing

In Part 2 of our series, our video shows poorly installed air conditioning unit flashings. The result is, of course, a leaking roof.

Roof flashings are a vital element of the roofing system as they are used to transition from the roofing material to something that is not a roof. Typically on a metal roof the flashing is also metal.

In the case of an air conditioning unit, metal flashings are required to create a watertight join between the unit and the roof sheets. The metal flashings need to be riveted and sealed into place to prevent water entering between the joins. Ideally, the silicone sealant should be applied to the underside of the flashing join to limit the breakdown of the sealant which naturally occurs over time with exposure to weather.

See our pics of flashings we’ve installed to rectify leaking ac units. Flashings are a permanent solution for this type of problem. The application of a liquid rubber membrane is an alternative cheaper but short term solution for this type of problem. We’ve included some pics of this fix too.

Roof Leaks on Commercial Buildings – Part 1

Roof Leaks on Commercial Buildings | Taped AC Pipes to Prevent Water Ingress | Melbourne | Roofrite Commercial

Roof leaks on commercial buildings

Roof leaks on commercial buildings can have many causes but time and again, as Roof Plumbers, we see roof leaks caused by poorly installed air conditioning units. Let me clarify that statement a little. The ac unit has been installed properly in that it does its job – heating and cooling. But the actual placement of the unit on the roof and through the roof is usually where the problems occur.

Air Conditioning Units

This short video (just under 2 minutes) shows two primary problems: too many ac pipes running through one roof penetration and the unit itself sat on treated pine support timbers.

Problem 1: Multiple Pipes through One Dektite

When more than one ac pipe at a time is fed through the roof, water can capillary down between the pipes, enter the roof cavity, and then drip onto the ceiling below. AC pipes should be cut through the roof one at time. That is, one pipe per Dektite!

Problem 2: Treated Pine used for AC Support Base

AC units generally need to have a support base for the brackets. All too often, we see treated pine used for this purpose. The problem with treated pine is that the chemicals leach out of the timber and react with the metal roof. As the video shows, the result is a fast track to rust.

The Solutions

Fortunately, both of these situations have a relatively easy and low cost fix. The pipes can be separated and run through individual dektites or taped to severely inhibit water ingress.

The treated pine can be removed and a metal cover (hopper flashing) can be made to run across the rusted area to prevent future rainwater entering the rusted area.

Call Roofrite today if you suspect this is the cause of your leaking commercial building.