Water is the number one cause of roofing damage. Leaks can create mold or pest infestations, weakened internal building structures, damaged insulation, and many other critical issues that only worsen if left untreated. Preventing water from penetrating your roof is therefore of utmost importance for the safety of your building, people, assets, and, ultimately, your business as a whole!

Thankfully, your commercial roof drainage system is designed specifically to handle this crucial task, and it will continue to operate flawlessly as long as you keep it in tip-top shape. Keeping your drains clean and clear of clogs that could create leaks is the most effective thing you can do to maintain the drainage system. Follow this step-by-step guide to understand how to clean your commercial roofing drains.

Clear Away Debris

First, you’ll want to clear the entire rooftop of debris. It’s easy for leaves, sticks, animal left-behinds and other kinds of dirt to accumulate and gather around the drains. Use a broom or brush to sweep away anything blocking the drain domes so that you can open it up without allowing more clogging agents to find their way into the internal piping.

Inspect the Drain

Once the surface of the drain is clear, you’ll be able to take off the dome according to the manufacturer’s instructions. Use a flashlight to peer inside the mouth of the pipe. This inspection is a key step because you don’t want to send water or cleaning tools into the opening if something is already blocking it. Keep in mind that small critters and birds might have made your roof drain their new nest. If that’s the case, it’s best to call your local animal control service to relocate the creatures without hurting them. Otherwise, make sure to wear work gloves to protect your hands as you manually remove any other debris from the opening.

Use Specialized Tools For Removing Clogs

There may be clogs further along the pipe in areas you can’t observe from the surface of the drain. If that happens, there are a couple of methods you can attempt to remove them.


Feed a regular plumber’s snake, found at any hardware or home improvement store, into the drain and rotate gently to loosen up the clog. Do not use a long stick as a snake since it may break inside the pipe or cause expensive damages. Repeat the insertion as many times as needed.

Power auger

A power auger can also help loosen up tough clogs. If you don’t have one, many hardware stores rent them out. Just be careful not to crack your pipes with it.


Do you have a standard garden hose you could bring in? Or does your facility manager or custodial crew know where to find one? Insert the hose into the drain until you feel the blockage, then turn on the water full blast to force it out. You may find the water gets backed up until it overflows from the drain mouth. That’s perfectly fine because it means the water pressure is building up. Eventually, the clog will break loose, and the water will flush away with it.

Pipe brush

If the water pressure alone doesn’t work, you can supplement the job with a pipe brush. Insert the brush as far down the drain as you can until it breaks down the stoppage point, then flush with water. A pipe brush is also a handy tool for cleaning the sides of the drain.

If none of these options work out, it may be best to call your roofing maintenance contractor to take a look. While there are other methods to clearing clogs, such as using a sewer jetter or blow bag, the risk of damaging your drainage system is higher if you do it yourself. Professional help at this stage is a wise move.

In Conclusion

Make sure to clean your commercial roof drainage system at least once every three months and every month during your most inclement weather-prone seasons. While you’re at it, you might as well do a brief inspection of your roof as a whole. Are there any noticeable areas of damage like ponded water, sagging, or holes in the roof membrane? If so, you’ll need to call your trusted roofing contractor to perform a formal inspection and make the necessary repairs. Otherwise, cleaning your roof drains is a free and simple way to keep your commercial property in pristine condition.

By Punit