Solving Chronic Gutter Overflow at Monadnock Indoor Tennis Club

Large buildings often reveal gutter problems that are easy to miss until water starts getting inside.

At the Monadnock Indoor Tennis Club in Peterborough, New Hampshire, the existing gutter system was struggling to handle the amount of water coming off the building's large flat roof. The symptoms were clear:

• Overflowing gutters during heavy rain
• Water getting behind the gutter system
• Damaged fascia boards
• Interior leaks
• Basement water issues
• Sagging gutter sections

The solution wasn't simply replacing old gutters with new ones the same size. The building needed a drainage system designed around the size of the roof, the length of the gutter runs, and the weather conditions common in New Hampshire. In December 2024, we completed a full commercial gutter upgrade built to correct the drainage problems and hold up for the long term.

The Problem: An Undersized Commercial Gutter System

The original gutter system was undersized for the demands of the building. The facility had long gutter runs but only small 5-inch gutters and four 2x3 downspouts located at the corners. For a residential home, that setup can work fine in a lot of situations. For a large commercial building with a flat roof, it created a drainage bottleneck.

Commercial Gutter Inspection Findings in Peterborough, NH

When we inspected the building, several issues pointed to the same underlying problem: the gutter system wasn't designed for the amount of water the roof actually produced.

Undersized Gutters

The building had 5-inch gutters installed along large sections of the roof. Sizing a gutter system correctly takes more than matching it to the building footprint — roof size, roof pitch, drainage paths, rainfall intensity, and outlet locations all factor in. This building had a large flat roof collecting significant runoff, and the existing gutters simply didn't have enough capacity during heavy storms.

Too Few Downspouts

One of the biggest problems was the downspout layout. The long gutter runs were sending large amounts of water toward the corners, where only small 2x3 downspouts were available to remove it. Water can only leave the gutter as fast as the outlets allow it to. When too much water is forced through too few downspouts, the gutter itself becomes the bottleneck — and the result is overflow, especially during intense rain or fast snowmelt.

Sagging Gutters and Poor Support

The existing gutters were also sagging in areas. A gutter that isn't properly supported can develop low spots where water collects instead of flowing toward the downspouts. As water sits in those spots, the added weight puts more stress on the system, creating a cycle of sagging and overflow. For a commercial building in New Hampshire, proper support matters even more, since gutters have to handle rainwater plus snow and ice loads.

Water Behind the Gutter

Another concern was water getting behind the gutter system. When water doesn't enter the gutter properly, it can run behind it and soak into the fascia boards. Over time, that leads to rotten fascia, wood damage, interior leaks, and higher maintenance costs. A gutter system needs to work together with the roof edge and drip edge to direct water where it belongs.

Why the Original Gutter System Failed

A large flat roof creates a different drainage challenge than a typical home. Water concentrates into long runs and needs enough capacity and enough outlets to move away from the building efficiently. The original design had three main limitations:

• The gutter size was too small for the roof's demands
• The downspouts were too small and too limited in number
• The long gutter runs let too much water collect before reaching an outlet

The building needed a complete drainage solution, not just a replacement gutter.

The Results: A Properly Sized Commercial Gutter System

The completed system addressed the original drainage problems. The Monadnock Indoor Tennis Club now has more gutter capacity, better water flow, more efficient drainage, stronger support, and better protection against fascia and foundation damage. The system was designed specifically for this building, not a one-size-fits-all replacement.

Six Months Later: How the System Performed Through Winter

A gutter system shouldn't only look good on installation day — the real test comes after it's been through New Hampshire weather. This project was completed in December 2024, right before winter conditions arrived.

After a major winter storm, we returned to the property to help clear snow from the flat roof. Even with a properly designed gutter system, flat commercial roofs still need snow management when loads get heavy. While we were there, we inspected the gutter installation. It held up as expected — the gutters stayed secure, the added support points were performing properly, and the drainage improvements were working as designed.

That follow-up visit matters to us. Finishing the installation is only part of the job. Watching the system perform through a real New Hampshire winter is what confirms the design choices were right.

What Other Commercial Property Owners Can Learn

A gutter system isn't just a metal channel bolted to the edge of a roof — it's a drainage system, and the right design depends on roof size, roof shape, gutter length, downspout placement, material strength, and local weather conditions. When a large building has drainage problems, replacing the gutters with the same size system rarely solves it. The better question to ask is: why did the original system fail? Once you know the answer, the right solution gets a lot clearer.

Built for New Hampshire Conditions

Commercial buildings across New Hampshire deal with heavy rain, snow accumulation, ice, and freeze-thaw cycles all in the same year. That's why we design gutter systems around the building and its environment, not a standard template. For this project, that meant larger gutters, stronger materials, more drainage points, better support, and long-term protection. The goal was simple: build a gutter system that still works when the weather gets difficult.