How To Install A Drain On A Commercial Flat Roof

We recommend hiring a professional.

Why Hire a Professional?

A flat roofing professional will typically install a drain in five steps.

Step 1: Survey the Rooftop

Once areas are marked out on the rooftop, the next step is to go inside and verify that the drains can be placed in those locations.

Step 2: Inspect the Roof Underside

For example, the drain line you want to install might have to run in a specific direction, but a large steel beam is in the way. You can’t cut through the beam, as that would weaken the building structure. You also don’t want to go underneath it, as it would disturb the finished look of the building. This is where those additional marked puddles come in. Hopefully, one of those is past the beam or helps you avoid it in some other way.

Step 3: Create a Sump

Mark out a square for the sump, either 4×4 or 8×8 feet. Insulation manufacturers now make sumps out of pre-cut insulation. These are convenient but not strictly necessary if you know how to use tapered insulation to build a cricket. A sump is essentially an inverted cricket, where the water is directed to the center of the pan rather than away, as in a cricket.

Step 4: Install the Drain

Step 5: Plumb and Test

In Conclusion

While understanding the steps involved can be helpful, hiring a professional is the best way to guarantee a reliable and code-compliant installation. With the right expertise, your flat roof drainage system will function efficiently and protect your property from water-related issues.