James Dulley, Published August 21 2009
Lumber-framed houses are still quite popularDear Jim: I plan to build a new house. I know a traditional lumber-framed house is not the most efficient, but I have a cheap source of lumber. What are some tips for building an efficient house with standard studded walls? – Pat L.
Dear Pat: Many houses in the United States are still being built to code with traditional
2-by-4-inch studded lumber walls. Within the past several decades, there have been many newer efficient building methods developed, such as foam blocks, SIPS (structural insulated panels), domes, etc., but they have not dominated the new housing construction market.
There are many reasons for this even though traditional lumber framing is typically not the most energy efficient. Lumber is relatively inexpensive, renewable, and these construction methods are simple and well understood. Also, building codes are often slow to change to accept new, more efficient house construction methods.
Since you have an inexpensive source of lumber, building a lumber-framed house would make sense. Even though lumber is a renewable resource, good-quality lumber is not always in the greatest supply. Luckily, the most energy-efficient framing methods also use the least amount of lumber. Energy-efficient engineered lumber can also often replace solid lumber.
People often think wood is a good insulator because it is full of pores and it floats. Although wood conducts less heat than metal or some other materials, it certainly is not a good insulator as compared to Fiberglas batts or rigid foam board. Every square inch where there is lumber instead of insulation inside a wall cavity, energy will be wasted.
The key to building an efficient lumber-framed house is using the proper-sized lumber sparingly. For example, building a framed wall with
2-by-6-inch studs on 24-inch centers is much more efficient than with 2-by-4-inch studs on 16-inch centers. When you see an old house, which was built before energy concerns, it is amazing how much excess lumber was used in the walls.
During the design conception stage of your house, plan the sizes of the exterior walls and interior rooms in 2-foot increments. This minimizes the amount of wood wasted because lumber is typically 8, 10 or 12 feet long. This also minimizes the need for extra support pieces in the walls, leaving more room for insulation.
Locate the doors and windows so one side lines up with an existing wall stud. This minimizes the need for extra opening framing studs. Even better, size the windows so their rough opening fits perfectly between two existing studs. Your insulation contractor will also appreciate this because it minimizes the need for odd-shaped pieces of insulation.
When building a two-story house, design it with stacked wall framing so the second floor studs line up over the first-floor studs. This is strong and stresses the headers less. Use two-stud corner construction instead of traditional three-stud designs for more insulation and less voids. Cover the walls with foam board insulation so the lumber mass is inside the insulation envelop.
Dear Jim: I have been getting ads in the mail about installing solar panels on my roof for electricity. Can these do-it-yourself solar panels produce 240 volts to run my central air conditioner on hot afternoons? – Ed J.
Dear Ed: There are tax credits now for installing solar cell panels to produce electricity, so there is a lot of marketing hype. Technically, the direct current output from solar cells can be converted to 240-volt alternating current with an inverter.
Practically, though, it would require a huge array of solar cell panels on your roof to produce enough wattage to run a central air conditioner. It could be done, but the installation cost would be huge with a long payback period.
Send inquiries to James Dulley, The Forum of Fargo-Moorhead, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com