Roofing & Exterior
When the Roof Is Big, the Gutter Has to Be Bigger
Custom box and commercial gutter systems fabricated to fit real building geometry and move the water a large PNW roof actually sheds — built to be maintained, not just installed.
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Signs to watch
Is this you?
Standard gutters can't keep up with the roof
A commercial roof plane sheds far more water than a K-style trough was ever sized for. When the volume is real, the gutter has to be fabricated for it, not pulled off a residential roll-former.
Overflow at parapets or internal drains in heavy rain
Internal box gutters and roof drains back up when they're undersized or clogged — and on a commercial building that water goes inside, not over the edge where you'd see it.
The building shape doesn't fit an off-the-shelf profile
Long runs, unusual fascia depths, and mixed roof levels need gutters made to the building. Custom fabrication exists exactly for the situations a stock profile can't cover.
No safe way to service what's up there
A gutter you can't inspect or clear is a gutter that will eventually fail unnoticed. Access has to be part of the design, not an afterthought once it clogs.
Your options
Fabricated to the building, sized to the volume
We fabricate box gutters and commercial profiles in the metals and gauges a large roof needs — both external systems hung at the eave and internal systems built into the roof structure. We size the trough and outlets to the roof area and the concentration points, not a default, and we design for maintenance from the start so the system can be inspected, cleared, and kept working over its life. This is owner-led commercial work; we scope each building on site rather than quoting a profile blind.
The method
How we do it
- 01
Assess the building and the volume
We walk the roof, measure the drainage areas and concentration points, and map how water moves off the building before anything gets fabricated.
- 02
Fabricate and install to spec
Gutters and outlets are made to the building's geometry and gauge, then installed as an internal or external system with the outlet and downspout capacity the roof volume demands.
- 03
Test flow and confirm access
We run the system and verify it drains under load, then confirm the maintenance access points are usable so the building can actually be serviced later.
Straight numbers
How commercial gutter pricing works
Custom box and commercial gutter cost is driven by the building — roof area and volume, metal and gauge, run length and height, whether the system is internal or external, and access. Because those swing widely, we scope each building on site and quote it specifically rather than guessing from a profile. You get a defined number for a defined scope before any fabrication starts.
Where we do this work
Box & Commercial Gutters: straight answers
What's the difference between a box gutter and a standard gutter?
A box gutter is a larger, custom-fabricated rectangular trough built to move high volume, often integrated into the roof structure rather than hung at the eave. Standard K-style gutters are formed from stock profiles for residential roof areas. When the roof is big enough, the box gutter isn't an upgrade — it's the only thing that keeps up.
Do you do internal and external gutter systems?
Yes. External systems hang at the eave and are easier to service; internal systems are built into the roof structure and route water through the building envelope. Which one fits depends on the building's design and where the water has to go. We scope both on site and recommend based on the structure, not a preference.
How do you size a commercial gutter?
From the actual drainage areas, the roof pitch, and where water concentrates — then the trough and, just as importantly, the outlet and downspout capacity are sized to carry that peak flow. Undersized outlets are a common reason a big gutter still overflows, so we size the whole path, not just the trough.
Can the system be built so we can maintain it?
That's central to how we design it. A commercial gutter that can't be safely inspected or cleared will eventually clog and fail where no one sees it. We plan maintenance access into the system from the start so it can be kept working over its full life.
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