Careful attention to sealing your new timber frame or log home during construction will help achieve an air-tight envelope for the life of the home.
Emphasis on energy efficiency in the construction of log and timber frame homes is nothing new. Building an energy-efficient home reduces utility costs, minimizes environmental impact, improves indoor air quality, increases comfort, and enhances long-term property value.
The evolution of energy efficiency continues to influence the design and construction of log and timber frame homes. The opportunities to take advantage of emerging technology, and best practices are more robust than ever. Energy efficiency in homes is influenced by insulation, windows, HVAC systems, energy-efficient appliances, building materials, air sealing, climate, orientation of the structure in relation to the sun and prevailing winds, and proximity to coastline or high altitude.
“With homes in the high mountains or at high altitude, for example, you typically have a range of atmospheres from intense sun in the summer and winter snow to very cold weather,” says Joseph Hochstetler, sales consultant with Hochstetler Homes (Loudonville, OH). “According to climate and location of the property we would recommend appropriate design features. So, if the home is in Colorado at 8,000 feet elevation we would recommend large overhangs for protection from the sun in the summer and offer R-60 attic insulation, to keep snow from melting and prevent ice damming. For windows, a smart sun glass or specialized glazing on certain sides of the house will provide enhanced energy efficiency as the home stays cooler in the summer and warmer in the winter.”
Energy efficiency is a straightforward proposition, but clarification of terms is important to understanding the process that achieves such standards. Log homes are naturally energy efficient and maintain more consistent temperatures than conventional 2×4 or 2×6 framed homes.
As a building material, wood offers benefits to homeowners, including R-value and thermal value. In short, R-value measures resistance to heat passing through the material while thermal value relates to the ability of the material to store energy. In log construction, the size of the logs, their structural fit, and quality chinking affect energy efficiency along with the species of wood. Research indicates that softer wood species such as “slow-grow” Eastern White Pine and Western Red Cedar may be more energy efficient due to their enhanced thermal values. Some log home suppliers have experienced quality performance with 6- or 8-inch diameter logs in climate extremes, while others may advocate logs up to 14-inches in diameter.
The Log & Timber Homes Council, part of the National Association of Home Builders, has noted in its recent energy performance white paper, “In practical terms, log homes may be expected to perform from 2.5% to over 15% more energy efficient compared to an identical wood-frame home, considering annual purchased heating and cooling energy needs.” Additionally, referencing the latest editions of the International Code Council publications provides insight in decision-making when it comes to the energy efficient factor. These include ICC-400 Standard on the Design and Construction of Log Structures and relevant sections of the ICC-700 National Green Building Standard.
Practical assessment of energy efficiency opportunities considers cost, complexity of construction, and aesthetic appeal. Placing the efficiency effort in perspective, consider that more than 30 years ago insulation was added to the discussion to raise R-factor by filling spaces where heat and cooling air might escape. Builders and homeowners recognized the importance of an essentially “airtight” envelope. Regular structural maintenance and upkeep including annual inspections to identify areas requiring caulking, sealing, reapplication of finishes, and other essentials became standard. These days, energy efficiency includes greater attention to the regulation of heating and cooling demand coupled with the utilization of renewable energy sources such as solar, wind, and hydro.
“These will help cover our growing use of appliances, entertainment, and communications devices that require power,” explains Rob Pickett, of Rob Pickett & Associates (Burlington, VT) a consultant on behalf of the Log & Timber Homes Council. “It doesn’t matter whether the house is log, timber frame, adobe, concrete, or stick frame – all can achieve the same results if they are properly designed and constructed.”
A significant note related to timber frame construction is the utilization of structural insulated panels or SIPs to enclose the frame. These components consist of a foam core that insulates and is contained between two structural facings, usually made from oriented strand board (OSB). According to the Structural Insulated Panel Association (SIPA), “SIPs are manufactured under factory-controlled conditions and can be fabricated to fit nearly any building design. The result is a building system that is extremely strong, energy efficient, and cost effective.”
SIPs are documented to provide roughly 50% more energy efficiency than conventional framing, says SIPA, while “a SIP building envelope has minimal thermal bridging and delivers excellent airtightness, which lends itself to LEED (Leadership in Energy an Environmental Design) and net-zero-ready building standards.”
SIPs are further recognized in enhancing air quality as their airtight envelope limits incoming air to controlled ventilation systems that filter allergens and contamination. Sustainability is highlighted with the reduction of CO2 emissions, and both construction and labor are accomplished with lower costs and shortened timelines.
Familiarization with local building codes and energy efficiency standards is a must in the construction process. Most building inspectors will not be familiar with log or timber frame construction. If inspectors need more information on energy performance, the log or timber frame producer you selected can provide appropriate building code information to educate them.
“One of the biggest challenges is getting governmental agencies in some areas to understand the effects that thermal mass plays in log homes,” notes Brad Neu, owner of Montana Log Homes (Kalispell, MT). “Log homes do require a bit more diligence on the part of builders to seal around windows and doors and properly seal checks in the logs. However, today there are great systems and products available that have simplified and improved weatherization in these structures.”
For homeowners who wish to evaluate the energy efficiency of their structure, evaluations are available from energy consultants. For example, a blower door test is ideal for detecting air leakage that can deplete energy efficiency and drive up heating and cooling costs.
A thorough evaluation of energy efficiency is standard practice in the construction of log and timber frame homes, as well as the assessment of efficiency in existing structures. Taking time to consider strategies pays dividends for years to come.