Is Your Roof Drainage System Protecting Your Building? 4 Things To Know

A properly installed commercial roof always features an efficient drainage system that quickly moves water away from the roof surface and into drains or gutters. Even if other elements of your roof may be performing well, an inefficient drainage system can compromise building integrity in a variety of ways, including causing water to pool on the roof surface. Eventually, a poorly planned or installed roof drainage system can cause serious leaks that can damage both your roofing system and your building’s interior.

Here are four key questions your roofing contractor should consider when installing your roof drainage system and when inspecting the one you already have.

1. Which is the condition of the metal used for gutters and downpipes?

Metal that’s used for gutters and downpipes on commercial buildings needs to be resistant to oxidation caused by water exposure — also known as rust. Steel may be stronger than aluminum, but aluminum fares better when it comes to consistent water exposure.

If the waterways of your drainage systems are allowed to rust, you’ll eventually have to deal with oxidative damage that can be hidden from plain sight. In the worst case scenario, fixing the problem could require ripping out interior drywall on several floors to replace downpipes that run behind walls —  a scenario that’s not only expensive but cause disturbances in the daily work environment.

2. What is the relationship of the roof to the ground?

The relationship of the roof system to the earth below is a crucial factor during installation — a roof drainage system must be able to carry the necessary “load” of water. Different roof slopes require different calculations but these two key factors that should always be considered:

• water load of the ground in relation to the water load of the roof
• depth, density and distribution of water on the roof surface

Not considering these factors can cause backups in the drainage system and, in addition, unwanted alterations to the ground caused by standing or flowing water. This is one of the reasons you should always have a commercial roof specialist and not building maintenance personnel inspect your roof and roof drainage system.

3. What is the drainage system water volume capacity?

The southeastern US can get a lot of rain! Because different geographical areas experience different levels of rainfall, you need a roof drainage system that supports the maximum recorded levels for all seasons in your area — and it’s a good idea to have a little wiggle room. If your roof drainage system isn’t adequate for the level of water it must transfer, water could pool during heavy rains and encourage leaks. Choose a roofing professional who’s local and knows what to expect in the wettest seasons.

4. Can you benefit from a roof that absorbs water?

Roof systems that naturally absorb water are best-known as green roofs or vegetative roofs. These roofing systems are covered with live vegetation and layer of soil underneath to support the plant root systems. With vegetative roofs, rainfall supports the roof system instead of potentially damaging it. And when water is absorbed by the roof instead of running off, many drainage issues can be avoided in the first place. Of course, vegetative roofs still need a good drainage system for when the soil’s water table is oversaturated. And if foliage-filled runoff from the roof clogs a downpipe, the clog can be “snaked.”

Does your roof need better drainage?

While the condition of metal, relationship of your roof to the ground and the volume of water your drainage system handles all play important roles in how your roof drainage system functions, leaks caused by roof drainage problems need to be assessed by a qualified roofing specialist. A water stain on your ceiling could be the least of your problems — the same leak can be causing serious damage behind your walls.
Sentry Roof Services can find any leak sources, assess your roof drainage system and either repair a problem area or offer other recommendations for remediation. Feel free to contact us if you have any concerns about your roof drainage system or would like a Sentry professional to come look at your roof.