Are Eavestroughs for Commercial Buildings Effective: 10 Things to Consider

Whether or not to have eavestroughs for commercial buildings is a common question we get from landlords. In most cases, if the roof is flat, the answer is no. But in some cases, eavestroughs can be a good choice for commercial roof drainage and protection. 

But are eavestroughs the best solution for your property investment? Here’s the low-down on what eavestroughs for commercial buildings are, when to use them and when to avoid them. 

The purpose of eavestroughs for commercial buildings

What is the purpose of eavestroughs for commercial buildings? Let’s start with a short definition. Eavestroughs are horizontal channels that run across the outside edge of the roof, collecting rainwater and snowmelt. As part of a comprehensive drainage system, eavestroughs drive water into a downspout, which diverts it away from the building.

When well designed, correctly installed, and in the right situation, eavestroughs prevent costly damage, tenant complaints and more. The right type of gutter building can prevent cracks in the foundation, basement flooding, damage to exterior walls, soil erosion, and landscaping problems. On the other hand, eavestroughs that are poorly designed or installed incorrectly can lead to the reverse situation: damage and costly repairs.

Now it’s time to look closer at eavestroughs for commercial buildings.

How are eavestroughs for commercial buildings different from internal drainage rain water leaders?

You’ve seen eavestroughs for commercial buildings where the eaves overhang the perimeter walls. The question is whether eavestroughs are the right type of rain water collection system for your property. This external system is different from internal drainage systems or those integrated into the roof.  

Eavestroughs don’t operate as a solo drainage system for flat roofs. They typically work in conjunction with components like scuppers, elbows and downpipes.

When are eavestroughs for commercial buildings an appropriate solution?

Do eavestroughs and flat roofs go together? It depends. They are most common on low and steep sloped flat roofs, residential properties, or light commercial structures. At the same time, there are specific cases where they are appropriate for commercial roofs.

These 10 considerations help roofers determine whether eavestroughs for your commercial property are appropriate: 

1. Parapet walls and roof edge design

Parapet walls will block water from reaching the eaves. This makes eavestroughs for commercial buildings ineffective unless scuppers or overflow drains are added. However, if the flat roof has exposed drip edges, eavestroughs may collect runoff effectively. At the same time, this only works if the eavestroughs can handle the expected volume of run-off.

2. Slope toward the edge

Even flat roofs usually have a slight slope (minimum 2%) to direct water toward the roof’s edge. Eavestroughs might be able to manage the runoff. That is, with the right slope to the roof’s edge and without internal drains or scuppers.

3. Local building code

The Ontario Building Code (OBC) mandates specific requirements for gutters on commercial buildings. Of note, Ontario runoff can’t be diverted to stormwater drains. Gutters and downspouts on commercial buildings are primarily addressed in the OBC Part 7: Plumbing. 

 

4. Building size

Internal roof drains or perimeter scuppers with downspouts are often more appropriate for large commercial buildings. Still, eavestroughs may be able to handle water loads for small to mid-sized commercial buildings.

5. Exits and entrances

Eavestroughs may be appropriate for exits, entrances, and other smaller flat-roofed sections if water drains toward the edge. The solution must ensure that rainwater doesn’t pour over someone at exits and entrances. 

6. Complex roof designs

Eavestroughs for commercial buildings are generally inappropriate for roofs with multiple levels, equipment, or penetrations. 

7. Aesthetics

Eavestroughs might be visually attractive on commercial buildings depending on design choices, materials, and architectural style.  

8. Cost

Eavestroughs are easier and less expensive to install than internal drainage systems or custom-fabricated box gutters. They are also easier to dismantle if changes are made to the building.  They also prevent the rain water from coming inside the premises.

9. Maintenance issues

Eavestroughs are harder to clean or maintain on tall commercial buildings, often requiring ladders or lifts. Other factors include roof access, gutter location, weather conditions, and safety regulations.  The run off from downpipes can be a source of soil erosion and also a trip and fall hazard.

10. Climate and precipitation

Eavestroughs must be used judiciously in Ontario. High-rain and snow zones may require greater capacity drainage. Special protection, such as heat tracing, might be  required to protect the eavestroughs.

Can they withstand Ontario winters?

Ontario’s heavy rainfall, snow, ice, and the freeze-thaw cycle can cause backups, ice dams, and leaks. Here are several methods for preventing this from happening.

Waterproof self-adhesive bandages

Roofers can enhance waterproofing with self-adhesive bandages at the roof’s edge and downspouts. This method is particularly useful in areas prone to ice damming, water backup, and wind-driven rain. Effectiveness will vary based on the type of roof system and the downspout’s integration into the roof or drainage system.

Heat tracing with automatic temperature sensors

Heat tracing wire and automatic temperature sensors are critical as a de-icing system in snowy areas with freezing temperatures. When temperatures dip below zero, the sensors automatically activate and control the heat cables. Heat tracers can be installed in the gutter, downspout, and/or on the roof surface.

Leaf guards

Leaf guards help prevent debris from causing clogs, backups, and spills over the side of the eavestrough. They are especially helpful when trees are above the eaves line. Even with leaf guards, visually check that eavestroughs are kept clear. This is especially true before wintertime, when access is more difficult.  

Are eavestroughs the right solution for my commercial building?

Eavestroughs for commercial buildings can be effective when part of a well-planned, installed, and maintained roof drainage system. Project specifications for commercial, industrial and institutional buildings will include the drainage system. A qualified roofer can review the drawings and then provide input as needed, particularly about installation. 

Hire a high-quality roofing contractor for a high-performing roof

When your building is new or is being renovated, a well-performing roof is critical for protecting your property and enhancing its value. Look for a roofing contractor with a reputation for experience, knowledge and craftsmanship. Elite Roofing and Contractors have served the Toronto area for more than 60 years. Trust us as part of your construction team for commercial, industrial, institutional, and multi-residential properties. Get the #EliteAdvantage.