Every stage of construction or remodeling presents choices, often about dozens of different products and materials. On top of that information overload, there are fundamental design decisions -- sometimes stumpers that have no absolutely right or wrong answer.
Last week we looked at three of these debatable decisions about heating systems.
This week we'll consider three basic questions about construction: whether to build up or out when you add on; whether converting attics or basements for living space makes more sense; and choosing the most efficient roof design.
Building up or out
This complicated decision depends on many potentially limiting factors. On a small site, for instance, building out with a new foundation can conflict with zoning restrictions that control minimum yard sizes and the maximum footprint of buildings on the overall lot size.
Unless you fancy a skyscraping turret, you're not likely to run into height restrictions in the course of building up, adding dormers or an additional story.
Cost-wise, it's most economical to use undeveloped space you already own, which usually means the attic, cellar or garage. They are already closed in and typically require no excavation or foundation work.
When the choice is between building up or out, it is almost always cheaper to build up, assuming the existing foundation can take the extra load, as most can. You save the substantial cost of excavation and preserve existing landscaping (earthmovers can really carve up a yard), at the expense of a larger basement. That's generally not a problem because homeowners are looking for more living space, not more basement or crawl space.
Building up also has the advantage over small additions where existing heating, cooling, plumbing and wiring can be extended into the new space. It all depends on the capacities of existing systems, of course, but a first-floor addition reaching into the yard typically requires longer runs for pipes, ducts and wiring, and often its own small versions of new utilities.
To minimize hassle, building out on a new foundation is the way to go because most of the work can be cordoned off until the last minute when the new and old spaces are joined. Building up, contractors will be swarming through the house day after day, probably for months.
Converting attics or basements
Maybe bedrooms should be upstairs and rec rooms down, but for cost-conscious homeowners the most easily convertible space is probably the winner. But which one: attic or basement?
Economy depends a lot on what you have now. In the basement line, a walkout is generally best because a door, decent-sized windows and at least one wall at ground level reduce the cave-dweller feeling. It's sometimes a stretch to turn a mostly buried cellar with only a few foundation windows into a cheerful room, even with artful lighting and a lot of mirrors.
As attics go, the prime candidates already have headroom, at least in a room-sized area down the center. Adding skylights is easy and building dormers not too far behind. But stripping off a low-slope roof and erecting sidewalls under a new, higher roof is a much bigger project -- more like building an addition than converting storage space into living space.
If there is a crawl space and no headroom, or if the attic, whatever the height, is blocked by a maze of roof trusses, think basement.
In either location, unfinished (no drywall) areas are best. But as most utilities and their mechanical lines originate in the basement, it has the nod here. Plumbing installed below the soil pipe (the main drain) can require special equipment, such as a pump to elevate wastes for drainage. But finding space to run plumbing pipes, air-conditioning ducts and other lines through living spaces up to an attic is typically more complicated and costly.
Unfinished spaces also make it easier to install insulation and vapor barriers, and in some cases, additional framing. Downstairs, foundations already hold up the house and rarely need structural help. Upstairs, attics often do.
Building codes make a distinction between living space and storage space, which means many unfinished attics have smaller floor joists than the rooms downstairs. To meet code, you may need to beef up the floor, for instance, adding 2-by-10s next to existing 2-by-6s.
Building big or small overhangs
Some roofs have distinctive architectural lines. But most are interchangeable hats for houses that can be steeper or flatter with overhangs to suit conditions on site.
But there is no universally best design, even in the same climate. In the mountains, for instance, one classic if dated design is the snow-shedding A-frame. But traditional trapper cabins have surprisingly low slopes to keep in heat and wide overhangs to keep snow away from the building.
Both extremes have limitations. Steep slopes tend to have short overhangs that offer minimal protection to siding and windows. When a steep roof is extended too far, the overhang starts to block windows. On the other hand, steep slopes provide more attic headroom, aside from better weather shedding.
A low-slope roof won't shed snow as well, but the overhangs can extend well past the walls to better protect windows and walls. That's why it's a common design in hot and rainy climates.
If you want maximum protection, consider a hip roof. Unlike a typical gable design (an inverted V-shape that overhangs two walls), this configuration provides overhang protection on all sides of the building.
