Roof Leaks Caused by Air Conditioners

Roof Leaks caused by HVAC roof-mounted systems.

Air Conditioners on roofs that leak can cause hundreds of dollars in repairs. The problem is finding the responsible party. I can’t tell you how many times, year in and year out, how I have been blamed for a leaky roof I installed, only to find out that someone installed an AC on the roof poorly years after I did the roof.

When it leaks, who do you call, the roofer!

The photo to the right shows how an HVAC contractor from the Sacramento area has bent, broken and stuffed his roof mount HVAC stand poorly into this roof. There is no way this roof would not leak, and it did, and who did the homeowner call? Yep, you got it, me. Winner~Winner, Chicken Dinner. The shingles and underlayment needed to be repaired and during this job, a broken rafter was discovered and replaced. As you can see to the right the unit’s stand on the bottom left is extended more than the right side to make up the sag in the roof. The HVAC contractor cut a rafter and it loaded too much weight on what is called the cripple rafter which had no purlin support. { A cripple is a rafter that runs from a hip to a valley}

This HVAC contractor that did this horrible job is a large company that does a lot of advertisement, but will never get a referral from me because of this type of work.

There were many issues with this installation and don’t get me wrong because for the most part HVAC contractors are great. This installation was very poor and did not get inspected by the Building Department. I have seen many maintenance issues on an Air Conditioners that also caused leaks. I hate having to tell the customer they need to call the HVAC Contractor that works on the roof recently to come back out and fix this problem. Did you know I have seen small 1/2 holes stabbed into the elbow so the HVAC contractor can temp/test the return air, then leave that little hole. Yep, that leak. I could go on and on but I think the point is made. This area of the roof is most important to get right and hiring the best to do the two jobs is critical.

As a roofing contractor, it is good to have a few you can trust and use because things can really go well if the two know each other and work well together. The reason why is this, when the roof and HVAC are being done at the same time, both contractors that have worked together both understand each other's job responsibilities. Of course, having both jobs done by the same contractor would have the best results. There are not too many contractors that cross overtrades, so having the two contractors having past experience together is a good scenario. It normally goes like this.

The old HVAC removed. The roof is removed. Exposing the roof can be useful to the HVAC contractor setting the new curb or stand. Having the heavy AC unit off the roof the roofer can install the roofing easier and making a clean good looking job. The HVAC contractor then lifts the new AC and sets it on the stand and seals the unit to the plenum. Best of both worlds, if both are done at the same time. If not I advise an inspection of both contractors to make sure this area of the roof performs well for years.

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