Friday, July 20, 2012

Built-in gutters: Inspection, maintenance and restoration


Built-in gutters may be the most complicated system in the building envelope, yet they are also the most elusive when you start searching for information on them. Sometimes called Yankee gutters, box gutters or even Philadelphia gutters, it’s no wonder they remain a mystery to many. Built-in gutter systems are actually part of the cornice structure and drain through internal or external leaders. They are not readily visible from the ground, further lending to the mystery of their design and function. Because they are integrated into the structure, built-in gutter linings that fail will cause extensive damage to the cornice and, in some cases, interior of the structure.

A plate from a Victorian era pattern book depicting built-in gutters as part of a mansard roof system. Source: Miller, Charles. Architecture: Designs for Street Fronts, Suburban Houses, and Cottages. Toledo: S. Bailey & Eager, Publishers, 1868.



In “Traditional Rainwater Conductor Systems of the 18th and 19th Centuries,” Karen Dodge of the National Park Service states that built-in gutters were first adopted in North America during the 18th century in high-style Georgian and Federal-style buildings, usually institutional or commercial, where refined architectural qualities were desired.  Built-in gutters while highly functional also serve an aesthetic purpose.  As structures were erected in the classical order with elaborate cornices and entablature, it became necessary to collect and channel rainwater without detracting from the architectural character of the building.  Built-in gutters served this function well, hidden from sight and shedding water to the exterior.

A detail from the same pattern book.

Built-in gutters, today, are typically constructed in the same manner as they have been since the 18th century.  They are wooden boxes with bottoms sloped toward the outlets where water is drained to leaders, or conductor pipes, that channel the water away from the building.  The first gutters in this style were actually troughs or box gutters, carved out of wood, and rubbed with linseed oil or painted to protect the wood.  Corners and seams were bonded with lead wedges.  Needless to say, maintenance was critical to their success or failure.  Later, the advent of sheet lead allowed for broader gutters, as linings covered the wooden troughs.  By the end of the century, copper became available in the United States and a popular choice for gutter linings because of its durability and the functional nature of the material in a sheet metal application.


Rebuilding the framework will be necessary if built-in gutter linings are not maintained. Photo from author.

Inspecting and maintaining built-in gutters

The most common sign of water penetration is peeling paint and decay in the wood soffit under the gutter. Other signs are dark stains and mildew, or deterioration of masonry.  Water infiltration may be visible in attic spaces or areas beneath the gutters where plaster and other interior finishes evidence water damage. The sooner a leak or area vulnerable to failure is addressed, the smaller the scope and cost of repairs.  Cleaning out leaves and debris from gutters as often as necessary is essential for durability and proper performance.


Careful inspection by a competent roofer is critical to the longevity and success of the system.  He will look for defects such as localized damage due to fallen limbs or other debris; cracks from expansion and contraction at joints or folds; or pinholes from corrosion.  Roofing tar and other bituminous compounds should never be used to parch, repair or coat gutter linings.  It makes the condition of the gutter indeterminable, corrodes metal linings, will crack and fail quickly, and cannot be removed without destroying the lining.  Ice damming is not uncommon in the winter but should not be removed with sharp tools for obvious reasons.

Restoring built-in gutters

Restoration of long-neglected built-in gutter systems that leak and have caused decay in the cornice and roof structure is often complicated and can be costly. But once the work is completed, a regularly maintained, well-detailed system can last 60 to 100 years or more, depending on the life of the metal lining. A preservation architect or consultant should inspect the building, propose treatment options, develop working drawings and specifications, and supervise bidding and construction. Temporary protection and permanent repairs should be performed by a roofer experienced in this specialty on historic buildings.


Gutter lining sections are seamed, riveted and soldered in a proper application. Photo from author

"We encourage restoration of historic built-in gutter systems," says Michael Devonshire, a building conservator and principal at Jan Hird Pokorny Associates in NYC. "The use of modern building materials as an adjunct to traditional materials boosts longevity." Devonshire describes the typical steps involved with a built-in gutter restoration:
  • Strip off old gutter lining and two feet of the above roof cladding;       
  • Where rafter ends or lookouts are rotted, install sisters (new rafter ends adjacent to old ones) or scarf in new wood and sisters;
  • Replace old wooden gutter bottom with kiln-dried-after-treatment (KDAT) plywood treated for resistance to decay, minimal expansion and contraction, and increased longevity, sloping bottom toward outlet;
  • Install gutter lining: an elastomeric ice-and-water shield on the bottom (not always required); building felt; a slip-sheet of rosin paper; and copper on top (16 or 20 ounce, depending on the dimensions of the gutter);
  • Install on the roof decking above the gutter two feet of elastomeric ice-and-water shield (or copper flashing) and roof cladding over it; and,
  • Repair or replace cornice moldings and interior structural elements as needed.

The Copper Development Authority and SMACNA recommend the use of copper sheet metal because of its workability and durability in a roofing application. Indeed, many linings have lasted one hundred years or more.  Lead coated copper and tin/zinc alloy coated copper may also be specified for a variety of largely unsubstantiated reasons and mere speculation.  Aesthetically, however, the water staining caused by sheet copper can be minimized or controlled by using one of these alternative materials.  Gutter linings are sometimes replaced with EPDM rubber or similar membranes because of a perceived cost factor.  While there will be initial savings, the linings will need to be replaced more often and—ultimately—cost more in the long run.  
Lead coated copper is an acceptable material for the gutter linings. Photo from author


Eliminating built-in gutters

It is not uncommon for the historic homeowner or steward of a landmark structure to look at the estimated costs to restore built-in gutters and consider eliminating them from the roof system.  Before doing so, they must consider the manner in which this will be accomplished:  Will this require the plane of the roof to be altered?  Will it be visible from the street?  If so, is the property in a local historic district and possibly impermissible?  Will new hanging gutters be added at the eaves, affecting the appearance of the cornice and further inciting the ire of local preservationists?


If not, what affect will the water have on the exterior of the building?  How will the envelope be impacted?  What problems could this cause in the basement or—worse—the foundation?  Once these questions are realistically answered, the preservation of the built-in gutter system seems more attractive, if not a necessity.  An architect or preservation consultant whose practice focuses on historic structure envelope should be consulted before any such alteration is undertaken.   

Detail of built-in gutters at the Olana State Historic Site in Hudson, NY. Photo from the Historic American Building Survey
Final thoughts 


Built-in gutters are a complicated system in the building envelope and certainly one of the most expensive to restore if maintenance is deferred.   Because they are integrated into the structure, built-in gutter linings that fail will cause extensive damage to the cornice and interior of the structure.   A significant feature of the structure’s architectural character, they should be regularly inspected, cleaned, repaired, and maintained.  Careful, regular inspection by a competent roofer is critical to the longevity and success of the system.  An architect or preservation consultant whose practice focuses on historic structure envelope should be consulted before any dramatic alteration commences.   


6 comments:

  1. Important additional note regarding expansion joints from John Chan of The Durable Slate Co.:

    Copper tubing is probably about twice as thick as copper gutters and only about 1/2"-2" in diameter, so the thermal movement vs. rupturing is VERY different than in box gutters. Generally copper tubing has 90 degree bends in it attached with copper clamps/bells to allow for this movement, but they have quite a different requirement for expansion (around 300' for a straight run I believe?).

    We learned this lesson the hard way, back in the late 80's; we had to bite the bullet and replace all the box gutters on a very large house 1 1/2 years after we installed them. We re-soldered it many times, but it would just keep breaking. Finally, we got a hold of the SMACNA manual. I can say that since that time, we've installed tens of thousands of feet of box gutters all over the US without a problem. This website would have been a tremendous asset to us back then.

    CDA link:

    http://www.copper.org/applications/architecture/arch_dhb/gutters_downspouts/hung _gutters.html

    SMACNA link:

    http://www.imarksweb.net/book/smacna+standard+for+expansion+joint+spacing+in+gut ters/

    Traditional Roofing link:

    http://www.traditionalroofing.com/downloads/TR6_expansion_joints.pdf

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  2. “Built-in gutters may be the most complicated system in the building envelope…” – Right! That is why when it is neglected and it starts to deteriorate, it can cause extensive damage to the structure of the building. It can cause decay to the cornice and roof structure, and repairing it can be costly.->Cody Charlebois

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  3. Having gutters is such a convenience especially if you have rain barrels to fill or you don't want parts of your exteriors getting wet. I agree with Cody because some tend to take their gutters for granted. It wouldn't hurt to seek some assistance to help you in cleaning them, right?


    Deshazo Roofing

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  4. If installed properly, built-in gutters can be one of the most durable types of gutters. Old houses and buildings mostly have built-in gutters, and it seemed very popular during the old days mainly because it is not visible outside the structure of a building or a house. This allows the home builder to have a better design aesthetic on the exterior of the house where the gutter should be located. ->North West Exteriors

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  5. Great post, I appreciate you and I would like to read your next post. Thanks for sharing this useful information.
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