What Is a Downspout and What Does It Do?

Published March 6, 2015 by Whirlwind Team

metal buildings downspoutIt's raining, it's pouring..., and - if you've designed your building well - all that pouring rain is being directed off of your metal roof and away from your building into an efficiently designed drainage system. This system is comprised of multiple components, including waterproof or watershedding roofing materials, adequate gutters and downspouts. The latter component, the downspouts, are vertical attachments to the gutter that transport water from the gutters, down and away from the building's foundation and into your site's drainage system.

Downspouts Are More Than a Water Drainage System; They're an Investment in Metal Building Longevity

Your metal building's longevity is largely dependent on the quality of materials you select, as well as the level of "add-ons" and "accessories" you invest in. For example, a bare-bones metal building - sans gutters and downspouts - is much more susceptible to moisture damage and corrosion than one that includes these roofing accessories. Your downspouts are much more than hollow tubes that carry water from the roof to a final water drainage route; they are a means of keeping your building safe from rust, corrosion, mold and other undesirable side effects of a moisture-rich environment.

Let's step back a step and evaluate water drainage from top to bottom.

Water accumulates on a roof via rain, snow melt, ice melt or condensation. This is one reason why roofs are sloped. A flat roof allows these various forms of water to collect such that they place undue strain on the building's load and can begin to react with roofing materials, causing corrosion that leads to serious damage and/or the need for a whole new roof. Your roof's materials and slope encourage moisture to move down.

Next, the water needs to be collected so it doesn't pour off the sloped roof in sheets of water that drench residents, employees, guests or customers as they enter and exit the building. These sheets of water can also do damage if they are running down the side panels of the building and/or pooling around the foundation. Thus, gutters were invented to capture this water before it makes its way over the roof edge.

Finally, downspouts connect to the gutter system. The downspouts are fastened to the gutters via a hole and are installed vertically, along the sides of the building. The bottom of the downspout is typically angled out for several inches or more, depending on the water's final destination, to get the water away from the building's foundation. Failure to use a downspout system can result in flooding or standing water that compromises your building's foundation as well as building materials.

Tips for Getting the Most out of Your Downspouts

Install an Adequate Amount. If you skimp on downspouts, water will pour out of the gutters and over the roof's edge as if there are no gutters at all. The building rule-of-thumb is to have one downspout for every 20 feet of gutter as well as one at any corner that interrupts this 20 foot spread.

Maximize Their Distance Away from the Building. Getting the water down off the roof is important. Equally important is getting that water away from the building. Firstly, this will be done by installing the downspouts a few inches away from the building's surface. Secondly, the final end of the downspout should be angled and extended as far as possible from the building's foundation. These two steps will ensure that water makes as little contact as possible with your building's components and foundation.

Maintain Them as Per Manufacturer's Instructions. Metal buildings are incredibly durable and require very little maintenance when compared with traditional wood-framed counterparts. However, some level of maintenance is required and your gutters and downspouts are one of the items that should be checked on a semi-annual basis. Maintenance requires things like:

  • Installing screens or mesh filters where the gutter meets the downspouts to keep the water drainage system free of larger leafs, twigs and other debris.
  • Sealing and caulking joints and seams liberally to prevent leaking.
  • Inspecting gutters and downspouts for cracks, leaks, or holes and repairing them as soon as it is dry again.
  • Clearing gutters and downspouts of debris (most applicable during the fall and early winter when trees lose their leaves and higher winds are apt to blow dead branches, twigs, etc., onto the roof).
  • Replacing seriously compromised sections of gutter or downspouts so water runoff remains uninhibited.

Unless you are building in an extremely dry climate, odds are your metal building needs a gutter and downspout system. It's a simple and virtually foolproof way to protect both the interior and exterior of your metal building from moisture damage.

Contact Whirlwind to learn more about downspouts and other building accessories that are integral to your building's longevity.


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