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Log Home Basics
Log homes may be site-built or pre-cut in a factory
for delivery to the site. Some log home manufacturers can also customize their
designs. Before designing or purchasing a manufactured log home, you
need to consider the following for energy efficiency:
In a log home, the wood helps provide some insulation. Wood's thermal resistance or resistance to heat flow is measured by its R-value. The higher the R-value, the more thermal resistance.
The R-value for wood ranges between 1.41 per inch (2.54 cm) for most softwoods and 0.71 for most hardwoods. Ignoring the benefits of the thermal mass, a 6-inch (15.24 cm) thick log wall would have a clear-wall (a wall without windows or doors) R-value of just over 8.
Compared to a conventional wood stud wall [31 D2
inches (8.89 cm) insulation, sheathing, wallboard, a total of about R-14] the
log wall is apparently a far inferior insulation system. Based only on this, log
walls do not satisfy most building code energy standards. However, to what
extent a log building interacts with its surroundings depends greatly on the
climate. Because of the log's heat storage capability, its large mass may cause
the walls to behave considerably better in some climates than in others. Logs
act like "thermal batteries" and can, under the right circumstances, store heat
during the day and gradually release it at night. This generally increases the
apparent R-value of a log by 0.1 per inch of thickness in mild, sunny climates
that have a substantial temperature swing from day to night. Such climates
generally exist in the Earth's temperate zones between the 15th and 40th
Log homes are susceptible to
developing air leaks. Air-dried logs are still about 15–20% water when the house
is assembled or constructed. As the logs dry over the next few years, the logs
shrink. The contraction and expansion of the logs open gaps between the logs,
creating air leaks, which cause drafts and high heating requirements. To
minimize air leakage, logs should be seasoned (dried in a protected space) for
at least six months before construction begins. These are the best woods to use
to avoid this problem, in order of effectiveness:
Since most manufacturers and experienced builders know of
these shrinkage and resulting air leakage problems, many will kiln dry the logs
prior to finish shaping and installation. Some also recommend using plastic
gaskets and caulking compounds to seal gaps. These seals require regular
inspection and resealing when necessary.
Since trees absorb large
amounts of water as they grow, the tree cells are also able to absorb water very
readily after the wood has dried. For this reason, a log home is very
hydroscopic—it can absorb water quickly. This promotes wood rot and insect
infestation. It is strongly recommended that you protect the logs from any
contact with any water or moisture. One moisture control method is to use only
waterproofed and insecticide-treated logs. Reapply these treatments every few
years for the life of the house. Generous roof overhangs, properly sized gutters
and downspouts, and drainage plains around the house are also critical for
Building Energy Code Compliance for Log Homes
Because log homes don't have
conventional wood-stud walls and insulation, they often don't satisfy most
building code energy standards—usually those involving required insulation
Building & Restoration of Log Cabins
The foundation of a log cabin is made of stone pillars. The stones provide a sturdy base to support the cabin and act as a barrier between the cabin and the earth. The stones may settle over time and the foundation is carefully examined for damage or wear and subsequently repaired during restoration.
The walls are made of logs, placed either vertically or horizontally, depending on the style and size of the cabin. The logs are notched at the corners to allow them to fit together. Corner notching is a notable characteristic of log cabin construction because it provides stability by locking the log ends in place, enabling the logs to fit together in a secure manner. Many different methods of corner notching exist, ranging from simple "saddle" notching to the common "V" notching or "steeple" notching, which get their name from the shape of the notch cut into the wood. These notching methods are marked by a cut into the wood that allows another cut piece of wood to fit together like a puzzle piece. Another commonly used technique, "square" notching, differs in that the logs are secured with the addition of pegs or spikes.
The number of logs used per wall varies with the size of the cabin. The spaces between logs are usually filled with a combination of materials in a process known as "chinking" and "daubing." This process seals the exterior walls, protecting them from weather and animal damage.
Log cabin roofs are often gabled and are comprised of hand-split, wood shingles. The roofs often develop damage and leaks over the years and are commonly included in restoration.
Many log cabins have both a front and rear door. Due to the many times the doors are opened and closed over the years, the doors are often not in good working order and require repair during restoration. Both doors on the cabin can be comprised of boards that are hand-dressed, open inward and are fastened to the log structure with pegs.
The cabin features two windows, located on either side of the chimney. The windows hold glass panes, which most likely need to be replaced during the restoration of the cabin.
The cabin has a chimney that sank and deteriorated into many different pieces over the years. The chimney was rebuilt during cabin restoration.
Handcrafted log home
A home that is constructed of logs that are
individually fit together.
Milled log home
Constructed of machine-lathed logs, and is also
used to describe a log home built from a kit.
Insulated log home
Constructed with half-logs attached to a standard
2x6 frame structure.
The mixture used to fill the gaps between logs -
can be natural materials or synthetic.
The normal loss of diameter in logs as they lose
The downward movement of log courses as the logs
The natural cracking of logs as they shrink.
Occur when two logs are placed end-to-end.
One layer of logs placed atop the entire foundation
of the home.
Log wall exterior
The inspector shall inspect interior surfaces of log walls, when such surfaces are visible, looking for:
In addition to the items specified in NACHI Standards of Practice 2.1 and 2.2, the inspector shall inspect:
In addition to the items specified in NACHI Standards of Practice 2.4 and 2.6, the inspector shall inspect: