Heres my problem. I own a 30-year-old, two-story, 2,500 sq. ft. developer-built Colonial on a shady lot surrounded by a wooded set-aside. Since the rear windows are small and there is only one single rear door that opens to a deck, the inside of the house is cut off from many lovely views and sight lines. Lately, Ive been thinking about adding a very modern, appreciably all-glass family room off the rear (and maybe enlarging other windows). How can I assure such a project would work architecturally? Specifically, what are some guidelines to help me appropriately reconcile the old and the new? I want to add not only winning views and glass, but also value.

– FT, Great Falls, VA

We are seeing a lot of interest in converting the well-located production house into a customized variant with improved sightlines, indoor-outdoor continuum and well-defined focal points. It is apparent that local homeowners dont want to simply occupy their homes; they want to enjoy them. Here are some practical considerations to the project youve described:

Views, privacy, sun control
For starters, orient the new rooms windows towards the best views of the wooded site. You are literally framing focal points which can add immeasurably to the rooms special appeal. But dont forget to screen out neighboring homes. Placing windows high in the wall or using appropriate window treatments can provide a strategic protection that will still keep sightlines open where desired. Also, French doors or sliders should be located for easy access to the back yard, patio or deck.

Since you are considering an all-glass room with tree cover, consider the potential heat gain from southern and western exposures. If your new room is exposed to direct sun you may want to consider glazing that reduces heat gain. Roof overhangs and slatted pergolas can curb sun penetration. Heat build-up, sun glare and wide temperature variances are the primary challenges in all-glassed-in rooms. When done correctly, though, an all-glass room is a real delight that offers life-enhancing connectivity to a pretty setting. 

As a footnote: our most successful postmodern additions have been minimalist utilizing floor-to-ceiling glass and carefully calibrated HVAC. A one-story rear addition should handily integrate with the two-story home youve described, and can offer considerable distinction and architectural interest. Some other considerations for marrying the traditional and the original:

Appropriate scale
Based on your homes size, structure and style, an appropriate square footage for the proposed addition would be about 16 x 20. Review all your functional requirements: the number of people you want to seat, furniture placements, media wall, circulation, access to outdoors and integration with the adjacent rooms. Functional requirements will dictate how the new room should be integrated with the existing house. If your existing home has an 8 ceiling height, consider a new room with 9 ceilings. A new space that drops down two steps creates an even more dramatic cathedral ceiling effect and improves outdoor site lines. Dont add steps if you will be regularly carrying food into the new space, however.

Tying off the roof
A sure way to integrate the new with the old is to replicate your homes existing roof slope. Matching rooflines help to visually reconcile newly added space, stressing the cohesion and unity of the whole. When exploring modern idioms, there are many roofing options. We have sometimes designed roofs that are slightly sloped to shed water. Flat roofs, on the other hand, are famously dramatic, but to stay watertight must typically be constructed in flat-seam copper which is more expensive. In a situation similar to yours, we recently specified a butterfly roof, which has a reverse pitch sloped up toward the wooded site, then designed a top-of-the-wall transom to maximize the visual linkage to treetops. If the design suits the house, add skylights or a distinctive cupola. 

Exteriors
Copying existing exterior cladding materials is generally both cost effective and architecturally appropriate. Two or three different exterior materials provide the palette needed for the new addition. For example, if you have a brick faade with wood clapboard siding on the other elevations, use brick up to the height of the new additions window sills with siding above. Of course, if you maximize windows there will be very little siding.

When your existing house has only one siding material, a different, yet complimentary, material gives the whole a welcoming visual variance. To create clean-lined, paneled exteriors that work well in new additions with large window walls, we often use cementitious panel products.

Following these design guidelines, your new room will be aesthetically integrated with the existing home, suit your functional requirements and maximize the market value of your home. When properly designed, your new family room will capture the unrealized potential of your lovely wooded site.

Bruce Wentworth, AIA, is the principal of Wentworth, a residential architecture, interiors, and construction practice. For question about architectural style considerations in the greater Washington area, consult our free resources.

Editors Note:  Before you make any addition to your home, be sure to contact the Alexandria Department of Planning and Zoning at 703-838-4660.