doors, windows, hardware

Wall of Windows

The scale of a main street window restoration can be daunting, but the results are worth the effort, according to an historic window specialist.

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The historic five-story Porteous Building in Portland, ME, features Chicago-style windows on the second through fourth floors. The fifth story above the cornice forms a fully developed “attic” with a row of arch-topped double-hung windows. When the Maine College of Art began restoring the building, it decided to rehabilitate the historic windows. Photos: John Bald

By John Leeke, Historic HomeWorks

When the Maine College of Art began renovating the Porteous Building in Portland, ME, the historic wood windows had fallen into a state of disrepair, and internal renovations had blocked natural light from penetrating the building. After briefly considering replacement windows, the decision was made to restore the original windows, while also renovating the interior to allow light into the building. The result not only brought back an historic building, but also enhanced the main street of Portland’s central shopping district.

Built in 1904-06 as a department store, the Porteous Building rises five stories above Congress Street in Portland. The front façade is richly decorated with terra cotta and wood in the Renaissance Revival style. The Chicago-style windows on the second through fourth floors are flanked by Classical pilasters. The fifth story above the cornice forms a fully developed “attic” with a row of arch-topped, double-hung windows. The original function of this wall of windows was to capture light and feed it deep into the building to illuminate the goods for sale. This was a time when natural light was considered more beneficial than the rudimentary electrical lighting of the day. The department store kept up with new merchandising methods as they developed throughout the 20th century, making use of improving artificial lighting and controlling the customers’ shopping experience. Several interior renovations eventually led to building partition walls just a few feet inside the front façade, excluding all natural light.

The Maine Historic Preservation Commission had identified the front façade and its windows as making a significant contribution to the character of the building. The façade is built of terra cotta, wood and glass. This principle historic feature had remained largely unchanged over the decades.

Field notes provided information on the condition of each window.

Project Development
In 1993 the Maine College of Art began adapting the building to the new use of arts education. The project started with planning for interior renovations. Often, the planning and implementation of these projects are spread out over several years into phases as funding becomes available and as the program for building use develops. Working together, the college, the architect and the commission developed a separate phase of work with a strong historic preservation philosophy to save the architectural character of the front façade. The window work was done in 1998, as part of the façade project.

Natural light is of paramount importance in the visual arts. Because these windows were originally designed and built to maximize natural light, bringing that function back was a matter of peeling back the later renovations. The interior partitions were removed so natural light could once again fill the interior spaces. The existing windows had been largely ignored over the last half century, which was both good and bad. Good because all the original parts and systems were still there; bad because they were mostly inoperable. The one type of maintenance they had received was painting – many, many coats of paint – that had sealed most of the windows shut and was now failing and peeling away.

“Daylighting was also critical to the success of meeting energy-efficiency design requirements,” says Richard Renner, AIA, project architect, of Richard Renner Architects in Portland. “We could have replaced these windows with modern units that would have saved heating dollars, but the façade just would not have had anywhere near the character as with the original windows.” Keeping the continuing cost of building operations as low as possible was important to the college and saving the original windows leads to that goal by saving on the cost of electrical lighting. “Once we had arrived at the decision to save the old windows, we needed an expert opinion on the validity of doing that in general, and then in particular, how to do it,” says Renner.

My work as the project’s historic window specialist was to assess conditions, suggest methods for refurbishing the windows and then help determine if that fit into the overall scheme of the project. Then I wrote detailed specifications for the window work, which the architects folded into their overall project manual.

The transom lights on the windows for the second, third and fourth floors are filled with “Luxfer” prism glass with zinc and lead cames. These ribbed panes are designed to send the exterior light deep into the interior space. Photo: John Leeke

Assessing Conditions
I followed my standard practice of first determining what we had to work with before even thinking about what specific treatments should be used, giving each window individual consideration. I began with a quick survey of all windows to determine the types of windows and general conditions. This helped me focus my detailed comprehensive assessment, which included an inspection of every one of the 105 windows in the façade. The strategy that each window should be given separate consideration and individualized treatment has the most effect on project costs and success. Here is my assessment procedure: 1. Determine the windows’ construction type, details and materials. 2. Survey the condition of all the windows, considering each window separately. 3. Identify the types of deterioration, their location and extent. 4. Determine the causes of deterioration, which are usually related to moisture and movement. 5. Prioritize the windows into three groups according to their condition: poor, high priority; fair, medium priority; good, low priority. The central lights of the Chicago-style windows are filled with thick plate glass and flanked with casement sash that operate on vertical pivot hinges. Transom lights above are filled with “Luxfer” prism glass in zinc and lead cames. These ribbed panes are designed to bend the exterior light as it passes through the window and send the light deep within the interior space. The fifth-floor arch-topped windows are double hung on chains and weights. Many of the sash were painted shut, and most of the sash chains were painted stiff. There was extensive paint and putty failure on the woodwork, with some limited broken and missing glass. Of course, the heavy paint buildup contained lead, which presented heath risks. But the woodwork of the windows was generally in good condition under all the paint. There were a few places where the windows had to be cut for installation of exterior lighting, flag poles, etc., and many very localized deteriorations such as pockets of decay and split wood near pivot hinges.

Once I knew the windows and their condition, I selected an approach that would contribute to the overall project objectives. These included: preserving the architectural character, providing effective lighting for art studio and library study needs and contributing to energy efficiency and long service life with effective maintenance options. I considered complete replacement (but not for long), spot repairs and maintenance (which would have a relative short maintenance cycle) and a few other approaches. It appeared all the windows would respond well to a round of complete refurbishing.

The general procedure to refurbish windows includes the following steps.

  • Removing most of the heavy paint buildup in place using lead-safe methods.
  • Removing sashes from frames and installing temporary weather panels .
  • Moving sashes to on-site or remote workshop.
  • Detailed cleanup of frame and sill.
  • Repairing sills, paint sills and frames.
  • De-glazing (remove glass) sash, removing paint and cleanup.
  • Milling out stock for replacement sash parts.
  • Cutting and fitting stock for each sash repair.
  • Repairing wood of sashes.
  • Re-glazing and painting sashes.
  • Moving sashes back to site and distributing to window locations.
  • Re-installing sashes in frame with weatherstripping and tuning up for proper operation.

Then I turned to developing the specific treatments and repairs and to writing specifications for the work. I know that it is standard practice for architects to “stand at arm’s length” from the work and simply specify products and not get involved in “means and methods.” Simply saying “install these products” may work for building construction in general, but it is no assurance of quality and success in window preservation work. Practically all of the success in window work comes from the knowledge and skill of the workers, their methods, procedures and the even nuances of each individual’s techniques. How can this be controlled to assure quality? One way is by sampling the work during a separate testing and development phase and then making the sample a formal part of the specification. Another is through the selection of a contractor with qualified workers.

Specifications showed where repairs were needed for each window.

We wanted this window work to be done by knowledgeable tradespeople and contractors. One requirement commonly included in specifications is that the contractor has at least five years' experience and can provide contacts for at least three similar projects. I like to go beyond that to consider how many windows and how many projects they have done. From my own past experience as a tradesman, I know that if I have done something once it only proves it can be done, and the results will be unpredictable at best. If I have done it 10 times, I know the procedure and have experienced a few, but not all, possible results. When I have done it 100 times, the immediate outcome is under my control. After 1,000 times, the long-term outcome is under my control. I call this “The Orders of Experience.” So, when assessing the abilities of tradespeople and contractors I ask simple questions: How many pieces of wood have you cut to size? How many sashes have you glazed? How many projects have you done? With these answers, I am better able to predict the outcome of their work.

The project implementation was on a fast track. All of the local and statewide historic window specialists with this “order of experience” were booked months ahead and not available, which did not bode well for the project’s completion schedule. The contractor did have carpentry and painting crews available. Clearly, there were some on the crews with strong woodworking and painting skills, though none with historic window experience.

There were enough workers willing to learn something new that we set up a training component in the project. The window specifications not only listed the products, but I also rewrote sections with detailed procedures, and this became their training manual. I gave the workers formal training in the special methods needed, such as wood-epoxy repairs, and they picked right up on it. After training, I worked along with them for the first week or two, so they could see the rhythm of the work and step up their productivity. With this formal training and its repeated practice, I was able to bump the workers' order of experience up to a level acceptable for this project. Effective methods and proven procedures are experienced by the workers with this sort of training so they actually take them to heart and develop their own effective techniques. By mind, hand and heart they learn the art.

The tradespeople, contractor, architect and owner were able to follow through and complete all the window work. Paul Attardo of Portland, ME, was the project manager.

The immediate outcome of the work was excellent. All the windows looked good and operated correctly. But the real story is always learned in the long-term performance. After eight years, I have returned to the Maine College of Art to examine the windows and determine how they have held up under the severe Maine coastal weather and demanding institutional use.

My first step was to interview the facilities manager, Doug Doring. “There have been no problems with the windows whatsoever,” he said. Amazing! I examined the windows myself and found some evidence of active use, a little wear and tear, but all the sashes were square; and the paint and putty were holding out the rain. Every window I tried opened and closed with ease. I did find that one 3-in. stop-block – which keeps the sash from opening too high – was split. Not too shabby – small damage out of 105 windows. I also interviewed a few art students, who were happy to have the natural light.

I asked Richard Renner what were the two things that have lead most directly to this success. He replied, “The intrinsic quality of the windows and that the work of their restoration was done so carefully to begin with.” He offers this advice to fellow architects and building owners: “Don’t have the reflex action to simply specify new windows. New windows would have radically altered the appearance of this building. If you’re willing to balance energy efficiency with the essential character of the building, it’s worth taking a close look at maximizing the performance of what’s there, rather than tearing the windows out.”

John Leeke has been restoring historic windows since 1971 and advising on window preservation projects since 1985, most notably at Carnegie Hall, NYC; Jefferson Building, Library of Congress, Washington DC; Philadelphia City Hall and at many other state and local sites. John shares his window knowledge in his Save Your Wood Windows publication. He can be reached at 207-773-2306,

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