Roof Leak - When it is an HVAC Problem and Not the Roofers

It is raining heavily in California right now and the phones are ringing again; not for air conditioning, or heating, but for....you guessed it...for water leaks! Tis the season for those stained ceiling tiles. The complaints and confusions about the causes and responsibilities for water leaks got me thinking this would be a good topic for an article.

Water leaks during rain storms are always a tricky problem. One would think that if it's raining and the roof is leaking then it must be a roofer's problem. For commercial buildings it probably is 90% of the time. But occasionally it is not and that is when we are called to respond. If not installed properly, packaged rooftop air conditioners and heaters can be plagued by water leaks. So where is the water coming from? Here is our top 5 list:

Cracked roof seams around the platform which hold the unit

This is the most common cause of water leaks from HVAC units and really it can be solved by a roofer but we are often called out to patch such situations. HVAC platforms typically sit about 3 feet above the roof and the roofing material wraps up vertically to cover the platform. The point at which the roofing material bends to go vertical, over time, will crack and then leak. The easiest solution is to apply Henry's roofing tar to patch.

Improper flashing around the platform

This second most frequent cause is due to a common error made during installation. All platforms, because they are horizontal, should have a metal cap over them and that cap should overlap the roofing material. If they don't, water will seep under the roofing material and into the store.

Exposed ductwork on roof with leaking seams

If at all possible exposed ductwork on the roof should be avoided. It is very energy inefficient and ductwork exposed to the elements is hard to keep water tight. When water seeps in through the seams it can travel down the ductwork right into the store through the supply air ducts. What a mess.

Rusted out drain pan and or cap on platform

This situation gets a little trickier because it's sometimes hard to tell where the water is coming from. Air conditioning units sit on a platform which is covered by a cap. A typical ten ton unit can weigh close to a thousand pounds. So if there are any areas of rust and erosion of the cap or drain pan, the unit is not easily raised to find the source of the problem. No matter which way you do it the cost to repair is high and often the most affordable solution is to expedite the change out of the unit.

Drain pan leak

It does happen! It's raining cats and dogs outside, of course you think the roof must be leaking but the technician gets out there and low and behold the drain pan is leaking. Roofers and HVAC technicians love to play the blame game when it comes to commercial roof problems so just for the record I'll say it here.

Sometimes it is purely an HVAC issue!