Hide and Leak: Avoiding the pitfalls of concealed gutters

Gutters on modern buildings range from completely hidden to boldly expressed. The choice is influenced by the overall design objectives and the functional requirements of the building. 

Unfortunately for architects, there have been few good modern gutter options. Often costly custom-made solutions are required to achieve the design goals. Duragutter was invented by an architect to provide a broader palette of solutions. See how Duragutter extruded aluminum profiles are used as hidden gutters.

Many architects would prefer to do without gutters entirely, but given increasingly severe weather, this is often not an option. Hidden gutters provide the necessary function while not intruding on the design. The standard solution on many buildings is a parapet with a roof pitched towards a scupper or trough. This design has a few functional and aesthetic limitations.

Site-built troughs are labor intensive and prone to failure given numerous seams that are often submerged for long periods of time. The parapet requires expensive flashing on the top and inside, with visible seams every 10’  The scupper must be meticulously executed to prevent water from entering the wall cavity.  Typically the scupper drains into a collection box and downspout, which becomes a strong aesthetic feature for better or worse.

Site built troughs are labor intensive Custom copper troughs are costly

Duragutter has four profiles that enable a wide variety of hidden gutters for any slope roof.

The Trough (TR) is simply framed into a flat (low sloped) roof, with the “wings” sitting on top of the membrane and sealed in with cover tape.  The advantages over site-built troughs are:

1. Made from extruded aluminum, requires no support framing below.

2. Can be manufactured in lengths up to 40’, longer runs are made using the patented internal pin connection system.

3. Provides a clean look for troughs that are visible from upper stories

Trough (TR) profile in membrane roof

The Square (SQ) and Thin Line (TL) are troughs with grooves on the inside to lock in flashing and leaf guards. The ability to integrate flashing allows for flexibility in positioning the gutter and interfacing with a variety of adjacent materials.  In addition, the upper portion of the gutter is thickened to enable materials to be screwed directly into the gutter.  This is often used to conceal the gutter behind the exterior wall finish.

Both of these shapes stand apart from the trim, and cannot form continuous, uninterrupted lines.   For example, it is impossible to miter a copper gutter into a rake molding, a common detail on older homes. It’s also difficult to achieve perfectly mitered corners.  When going around a curve, copper gutters are usually composed of multiple short pieces soldered together, creating a faceted look that is subject to leaking.

Square (SQ) profile as traditional box gutter Thin Line (TL) profile behind soffit as fascia

The Wedge (WG) is a unique profile designed for sloped roofs.  While often used as a bold accent, it can also be contained within the roof/wall section.  The shape offers a great solution for designs where the roof and wall intersection is minimized.

Wedge (WG) profile flush with siding Wedge (WG) profile wall mounted as eave

A unique feature of all Duragutter profiles is the ability to place outlets in the back as well as the bottom of the gutter.  We custom make outlets to meet your design requirements, allowing more design flexibility to conceal downspouts within the wall section.

Square (SQ) profile with custom 4" round rear outlet

We are happy to provide technical drawings and create custom parts to help you achieve your design goals.

Copper Gutters Have Their Place (but it's probably not on your home)

Duragutter is made from extruded aluminum. We will explore why we chose to create a

new type of gutter to compete with copper

Copper has been used for centuries as a durable and attractive gutter material. It is highly resistant to corrosion, is easily formed, and when properly soldered is quite durable. It weathers to an attractive green/bronze patina which can be a nice complement to other building materials like wood and stone.

While it looks great on this French farmhouse, it's suitability for many American house styles is questionable.

Copper has a number of disadvantages. First, is the cost. While the price of copper fluctuates, it is generally quite expensive. Thus, thin sheets of copper are used to form gutters, which results in a relatively flimsy section, compared to the alternatives. Like roll-formed gutters, copper gutters require internal supports at regular intervals to keep them straight and protect them from collapsing under the weight of water, snow, or ice. From an installation standpoint, working with copper requires specialized skills, and the longevity of the joints is a function of the skill of the installer. With fewer people going into the skilled trades, finding a skilled worker to install and solder copper joints(or repair joints in the future)  is an increasingly difficult and expensive proposition.

External support brackets create a decorative element that may be at odds with the other design elements of the house. Internal support brackets make cleaning difficult.

Another issue with copper is the integration of the gutters as a trim element. While traditional wood gutters were used in conjunction with moldings to form an overall trim schema, copper gutters are generally only available in a “K” profile and a half-round.

 "K" style gutter Half-round gutter

Both of these shapes stand apart from the trim, and cannot form continuous, uninterrupted lines.   For example, it is impossible to miter a copper gutter into a rake molding, a common detail on older homes. It’s also difficult to achieve perfectly mitered corners.  When going around a curve, copper gutters are usually composed of multiple short pieces soldered together, creating a faceted look that is subject to leaking.

Advantages of Duragutter extruded aluminum: Extrusions are formed by pressing a molten blob of aluminum through a die under high pressure. 

Extruding gutters is a complex process- a hydraulic ram exerts over 100 tons of pressure. This process allows for intricate shapes that cannot be achieved through the simple bending process used to form copper, or roll-formed aluminum gutters. 

Duragutter extruded shapes have far more features than other gutters. The profiles above illustrate the system of internal keyways that all Duragutter profiles share. These allow for a variety of functions, including hidden internal connectors, built-in flashing, and snap-in leaf guards. The strength of the thick aluminum walls allows the gutter to be simply screwed in through the back wall, with no internal or external hangers or brackets.

Duragutter blends seamlessly with other trim elements, rather than standing apart like copper.

While we don't think copper is a great choice for gutters, it does make an attractive downspout :-)

Wellfleet Revisited

I vacation in Wellfleet every couple years, and while my wife is shopping or going to galleries I stroll around and photograph gutter details (I'm not sure how it came to this, but here we are...)

It's both depressing and annoying- so many fine homes ruined. Many of these botched jobs have been done by "experienced carpenters" who "take pride in their work". I'll let the pictures speak for themselves:

I guess the knowledge of how a gutter originally intersected a rake is almost completely lost. Out of about 60 houses, there were 3 that had the correct detail. I owe it to them to sing their praises.

The next one is a renovation by Hammer Architects. Kudos to them for getting it right! Tragically, they used wood gutters instead of Duragutter, so the system will drain about half as well and rot out in ten years, but at least they knew how to detail it correctly. Doesn't this look much nicer than all the botched attempts shown above? Shouldn't we all be trying to do it right? There are links to 3D models and drawings on the traditional detail tab that show exactly how to execute this detail.