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Design Strategies for Building Additions and Alterations

April 5th, 2016 by

When architects are tasked with designing an addition or alteration to an existing building, the attitude and orientation of the new to the old is critical to the success of the design.

Should the new relate to the old? Should it boldly proclaim its difference or discreetly extend the look of the original? The answer, of course, depends on lots of factors: the age and quality of the original building, the replicability of its features, the size and scale of the addition relative to the original structure, the functional and site constraints dictating the location of the addition, the material and textural qualities of the original, whether the original is worth preserving, and more. What follows are a few very basic design strategies for deciding what form and appearance a building addition or alteration should take depending on the situation.Contrast: Respectful Difference
In cases where the existing building is historic or otherwise desirable to maintain as part of the finished product, the most effective design strategy for a new addition is a clear contrast between old and new.  The temptation to try to copy or extend a beautiful historic building is strong, but the realities of 21st century construction make it nearly impossible to recreate the intricate details, ornate ornamentation, or aged/obsolete materials and features of historic buildings without generous budgets. Attempts to do so usually result in pale imitations that manage to detract from both the old and the new.

It seems counterintuitive, but the best way to respect and celebrate a beautiful historic building is usually to design with contrasts in mind. An addition to an ornate masonry building might feature lots of glass, crisp volumes, or contrasting colors. A rough textured wood siding might be paired with a smooth, sleek material. An architecture of mass and weight could be contrasted with light floating planes and volumes.

These considerations are exemplified by the renovation of the Park Plaza building facing Baltimore’s historic Mount Vernon Place. In 2010, a five-alarm blaze damaged most of the interior and the entire existing roof of the historic 19th-century mansion. The owners used the opportunity to enlarge the top floor (formerly a cramped attic) and provide a more open and prominent entrance lobby at street level.  To make an effective contrast with the old masonry building, the rooftop addition is clad entirely in glass and set back from the front and back of the building to give a clear visual break (and create dramatic outdoor terraces), topped off with a thin plane of a roofline that seems to hover above the massive old building. The new lobby mimics the rooftop design with an all-glass entrance and thin ceiling plane that floats out over the sidewalk for an entrance canopy.

Park Plaza Entry
Engulf: Transform the Old

When tasked with adding onto a building that’s ugly, unloved, or in poor condition, the simplest strategy is to conceal it and start fresh with a new design that transforms the old building into part of the new. This of course depends on the size and scope of the alteration: it needs to be extensive enough to visually suppress the old building.

The expansion of the YMCA in Catonsville, Maryland, shows some strategies for “burying” the old building. In this case, the old was a solid, gray, windowless concrete block swimming pool building that was a valuable functional asset on the inside, but completely featureless and ominous on the exterior, at odds with the friendly, welcoming image desired by the YMCA.  The expansion nearly doubled the size of the old building, taking on a completely different aesthetic of glass, stone, and clapboard siding.  Aside from its scale and proportions, the pool building facades were treated as a kind of blank canvas in which to integrate elements of the new architecture: a series of large new windows (both outside facing the parking lot and inside facing the new lobby), and a bright, welcoming yellow paint color.

Before_After Catonsville Y

Harmonize: Blending Together Old and New
Perhaps the most difficult design challenge is attempting to weave together old and new: trying to “harmonize” a new design with an existing one. This is often necessary when program or budget dictates an addition or alteration of similar size or scale to the existing building, or when the new and the old demand to be closely linked or integrated due to site constraints. This makes it challenging to set up an effective counterpoint strategy because hierarchy between the parts is difficult to establish and/or demarcation between them can be blurred.

An example of these constraints can be seen in the Charlestown Square community building expansion at a senior living facility in Catonsville, Maryland. The program called for new lobby spaces, expanded dining rooms, activity rooms, and swimming pool in a site constrained by surrounding buildings, and existing service and circulation functions to be maintained. This meant that a substantial portion of the 1980s building would be present in the final form: the prominent green hip roof, dark ribbon windows and pinkish brick would have to be reckoned with.

But since the program was not large enough to “engulf” the old, nor the existing building large or attractive enough to be celebrated in a contrasting relationship, the solution was to respect the centralized symmetry and scale in the addition to maintain the existing vehicular drive, drop off, and connection to existing elevators and internal functions. And because the addition is flanked by “wings” of the original building, we chose to extend some of the language and materials — the green hip roof, low brick volumes, cast stone sill lines — while leaving behind the dated dark ribbon windows, postmodern pediments, cupola, and pink brick color. Rather than simply copying what was there, decisions had to be made as to what was worth harmonizing with and what should be suppressed, and in what proportion.

Before_After CharlestownAfter Photo Credit: Kevin Weber

Also important to the harmonizing strategy is the degree to which the existing can be replicated or rhymed with effectively. Unlike Park Plaza, the existing Charlestown Square building was a relatively simple, recent building with elements like standing seam metal, brick and cast stone that were easily matched in the addition.

Most alteration projects are a delicate combination of all of these strategies, but choosing a general disposition of new to old is the critical first step to an effective composition.

Read more about Marks, Thomas projects involving additions and alterations by visiting our library of case studies.