Types of Logs

A log cabin can be made from virtually any group of tall trees.

However, a log cabin that lasts must be made from a narrow selection of wood types that have the characteristics needed to craft a sound, visually appealing structure that will retain its strength, value and appearance for decades and beyond. The following describes the common and not-so-common types of logs used in log cabin construction.

The fact is that the logs used in construction of your log cabin by a local company will offer as its most cost-effective option logs drawn from regional sources. Ordering and transporting logs from great distances is expensive. Most consumers will rightly flinch at the cost when locally sourced timber can provide the right quality logs at an affordable price.

Cypress

cypress

The wood from these trees found in the lower Southeastern portion of the country have a fairly solid reputation for resistance to rot and infestation.

However, this resistance is pegged to its deep interior or “heartwood” of the tree. A tree’s heartwood is usually visually distinct from its outer sapwood, which is typically lighter.

The sapwood of Cypress is very light and nearly white. Its heartwood ranges from light yellowish brown to dark brown or reddish brown. A Cypress log for use in a log cabin may not be milled sufficiently to expose the heartwood. Therefore its self-preserving properties remain trapped in the log itself. When this happens a customer has paid more than 2 times more for the log but their log cabin does not have the protection that they hoped to buy.

Cypress logs offer strength and durability. The prohibitive drawback of Cypress is cost – and availability. A Cypress log cabin can cost as much as 2 times the cost of a Pine log cabin. And, it is so difficult to gather in sufficient quantity, a builder often has to compromise on which logs must be used.

For most prospective buyers, the sticker shock of a log cabin constructed from Cypress logs is enough to send them shopping for a cost-effective alternative.
Douglas Fir

douglas_fir

The Douglas Fir is perhaps best known as a Christmas tree in cabins across America. Full- grown stands of Douglas Fir provide provides strong and durable lumber for construction purposes, including plywood and high grade veneer, interior trim, cabinets, pallets, boxes, ladders and flooring. It is also a good and plentiful tree for log cabins. The tree is plentiful and moderately priced when locally acquired, i.e. the Rocky Mountains and the Pacific Northwest up into Alaska.

As seen here, the sapwood is white to pale yellow. The heartwood is orange-red with a definitive contrast between earlywood and latewood. Overall the wood is straight grained and moderately hard. It is a good building material but delivery costs to the Eastern states are prohibitive for most customers.
White Pine

white_pine

White Pine is an eastern tree that is also sometimes decorated outdoors as a Christmas tree. As one of the fastest growing northern forest conifers, it is frequently used in reforestation projects and remains one of the most widely planted trees in North America. Eastern white pine is found across southern Canada from Newfoundland south to southeastern Minnesota and northeastern Iowa; east to northern Illinois, Ohio, Pennsylvania, and New Jersey; and south mostly in the Appalachian Mountains to northern Georgia and northwestern South Carolina. It is also found in western Kentucky, western Tennessee, and Delaware.

Its color is very light, shading from white to a pale yellow color. It darkens toward a tan color within a few months of installation. As a construction log, White Pine holds its shape well and can be effectively milled. It also is easily stained. Mature trees typically have no branches on the lower half of the trunk, meaning few or no knots. “White pine wood has medium strength, is easily worked, and stains and finishes well,” accords to the U.S. Forest Service.
Green River Cabins exclusively uses white pine logs in constructing the exterior portions and main interior beams in our log cabins. The logs we use are acquired exclusively from Ellis Lumber Company and Logs in Shelby, North Carolina, which acquires and mills its logs for us to the optimal 4’’x12” commercial size (actual size is 3.5”x11”). Before the logs are cut and delivered to Green River Cabins, Ellis inspects each log for quality upon arrival and again before departure.
The logs arrive at Ellis green, meaning recently cut, usually from a growing area within 200 miles of the plant site. The logs are then air-dried on the yard for 90 days. Next they move to a kiln for a two-week drying that reduces the moisture content of each log to an equilibrium moisture content (EMC) of 19 percent. This process is critical in achieving a stable, usable log. Green logs should never be used in the construction of log cabins–or virtually any other commercial product for that matter. The moisture content of logs must be reduced to increase log strength and prevent future twisting, warping and shrinkage that otherwise would inevitably occur. A properly dried log is also less susceptible to biological deterioration from fungi and insects.

schematic_dry_kiln

Schematic of a dry kiln. (USDA Dry Kiln Operator’s Manual.
(See http://www.fpl.fs.fed.us/documnts/usda/ah188/chapter02.pdf )

dehumidification_drying_system

Dehumidification drying system. (USDA Dry Kiln Operator’s Manual.
See http://www.fpl.fs.fed.us/documnts/usda/ah188/chapter02.pdf )

NeLMA explains the grade as follows:

D & BETTER SELECT

NELMA’s Eastern White Pine grade rules define the limiting characteristics (knots, holes, splits, etc.) allowed in each grade (quality level). While the rules describe the poorest piece permitted within a grade, it is unlikely the maximum size or number of these characteristics would be present in any board. D & Better Select is a combination of the top two Eastern White Pine grades, C Select and D Select. Material of this high-quality grade combination is used for natural or stained finish applications, fine woodworking, or interior trim. Although the reverse face of D Select shall permit sound characteristics typical of Standard grade material, C Select shall only permit the characteristics of D Select on the back.

D Select, which is the lower of the two grades, allows pin knots (maximum size is approximately 1⁄2”) and limits the total number of pin knots to one knot per surface foot. Checks and shake are barely perceptible. The occasional pocket is very small. A split will not exceed 1⁄2 the width. Pitch, when present, is evident, but limited by surface area of the piece. Medium stain (blue or coffee) cannot exceed 3⁄4 of the face surface area in a clear board, and less if present with other limiting characteristics. A larger surface area is allowable if the stain is light. Skip is permissible on the back face or one edge of 20% of the pieces. Wane is limited to the back face. Occasional pieces may require a cut to yield all useable lumber for finish work (loss not to exceed approximately 5%). Characteristics in C Select are no larger and less numerous than those same characteristics in D Select.

The “Standard NELMA Grading Rules for Northeastern Lumber” shows all allowable grade characteristics, which is posted at: www.nelma.org.
After being properly inspected and approved, the logs are shipped to Green River Cabins, where they are further expertly custom cut to size and cut again to form our signature dovetail corner.
Yellow Pine

yellow_pine

Like its White Pine cousin, Yellow Pine is easy to work with but is stronger even though it is more prone to shrinking or warping. Yellow Pine makes good floor joists and Flooring. When you visit 250 year old house museums, it’s common to see original yellow pine floors. The U.S. Forest Service agrees, noting that yellow pine is “less susceptible to dents, scratches, and other signs of wear. To consumers, that means that it is better suited for such uses as flooring, furniture, and other applications where durability is important.”

Yellow Pine is also decay resistant. As its name suggests, it is darker and has a distinctive yellow hue. It is less accepting of stains. Yellow pine is relatively inexpensive.
Other Log Varieties
Hemlock:

hemlock

An evergreen that is a heavy hardwood that provides good strength and shape rigidity. Cost is a factor for shipping outside its habitat in the American west.
Oak:

oak

Strong, durable and typically cost prohibitive.
Red Cedar:

red_cedar

Widely known as the fragrant wood used in chests and closets to prevent moth infestation, Red Cedar has a trademark pink-to-brownish-red hue. It is light but durable, especially in wet climates. It is moderately expensive.
White cedar:

white_cedar

A moderately strong hardwood resistant to rot and insects. White cedar is a great wood for porch railings and posts. If one were to use a wood other than cedar in the lower rail of a deck rail shown in the photo below, it is unlikely to last more than a year before it rots.

Exterior Finishes

The last and most important component of a well-built, long-lasting log cabin is its exterior finish. A quality exterior finish on a log cabin should serve to achieve multiple goals, including protection from weather and sunlight (UV), deterring insect, mold and fungus infestations, and providing a uniformly attractive color/stain of the wood grain.
In frontier times, American log cabins were left exposed to the elements with perhaps a little white wash and a lot of prayer to keep the cabin from being destroyed by weather or insects. Today, a line of modern products can keep your log cabin looking as good as the day it was built for generations to come. The key is selecting the right products.

a log cabin left to the elements.
log_cabin_decay

Like all residences, log cabins must stand up to a number of threats from Mother Nature. First and foremost is weather. Wind-driven moisture, be it rain, sleet, snow or even just high humidity, poses the biggest danger to a log cabin. The exterior profile of a log cabin is inherently more vulnerable to the elements than a modern home wrapped in vinyl siding. Water will destroy poorly treated logs fast. Logs permeated by water can warp and twist. Cracks can appear in less than a year. Inevitably rot will set in, threatening the structural integrity of the log cabin. Repairing (or worse, replacing) rotting logs is an expensive prospect that log cabin owners can avoid if they choose the proper exterior treatment.

The sun can also deteriorate log cabins. Discoloration and fading are the frequent result of UV damage to log cabins. Sun damage, typically does not harm the structural integrity of the log cabin. But for most log cabin owners, the unsightly graying of logs is an unforgivable outcome that undermines the key component of a log cabin—the beauty of the logs themselves.

A wood-decaying fungus can also endanger log cabins. The U.S. Forest Service lists several pernicious fungal types that threaten log cabins, including soft-rot fungi, brown-rot fungi and white-rot fungi. Each of these decays wood, sometimes with little visible exterior signs of damage. In other words, a fungal rot can destroy the wood from the inside out. Fungal rot starts with a breach in the log, be it a surface break in the log’s exterior coating or worse a crack in the log that allows water and fungal spores to get started.

An example of brown rot fungus damage.
brown-rot-fungus

The fact is, any untreated (or unfilled) opening in a log cabin, invites trouble. A crack in a log opens it to water permeation, which invites fungus and rot. Worse, a crack can invite a wood-boring insect infestation—carpenter ants, carpenter bees, wood boring beetles or even a full-blown termite colony.

A termite damaged log cabin.
Termite Damage

Paint

Regrettably, some log cabin owners have chosen to have their log cabin painted with traditional exterior paint. This is (or should be) universally known as a grievous error by the owner or a conscious attempt to hide rot and/or other flaws in the log cabin’s exterior logs. Paint is never a good decision nor a sign of well-kept log cabin.
Simply put, paint is not manufactured for use on log cabins. And the logs used in log cabins are not designed to accept paint. Steer clear of this option when building a log cabin or buying one from a previous owner.

Latex Stain

A latex stain is a water-based treatment that does not penetrate the log as deeply as other stain options. As such, it acts similarly to paint in its application and durability.

Latex is an attractive choice for DIYers given its ease of application and clean up (soap and water). Latex is a water-based product, which means it typically will emit less fumes that can irritate eyes, breathing passages and skin. Fumes from these applications are technically called volatile organic compounds (VOCs) and raise some larger environmental concerns. The EPA defines VOCs as a “large group of organic chemicals that include any compound of carbon (excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate) and that participate in atmospheric photochemical reactions. VOCs are of interest in part because they contribute to ozone formation (U.S. EPA, 2003a).” They also pose some known risk to human health. Government regulation is trending against applications with high VOCs.

Latex stains dry relatively quick, allowing a recoat in an as little as an hour or so. The per-gallon cost is between $25 and $40. The durability of latex stain, however, is suspect. After two-years (up to five, at best), depending on weather conditions and sun exposure, additional applications are needed. “Latex-base semitransparent stains are film-forming finishes and will not perform like true penetrating stains,” according to the U.S. Forest Service.

Latex exterior stains are available in opaque and semi-transparent. The more transparent the coating the less protection against UV fading is provided. So the trade-off is between visual attractiveness and durability. An opaque application hides the grain of the wood but protects longer. However, both options are prone to flaking over time.

Latex stains are improving, mostly due to the increasing emphasis on limiting VOC content, which is spurring rapid research and development of these stains. Still, they lag in quality when compared to traditional oil-based products.

Acrylic Stains

Although they can vary widely in quality, acrylic stains generally represent a step up in quality from latex stains. They range from water-based to oil-based, with the oil-bases providing better durability. Acrylics show wear and ultimately the need for reapplication by noticeable graying of

Acrylic stains range in price up to about $70 per gallon and can last up to 4-5 years. Green River Cabins has co-developed a lower-cost acrylic stain that retails for just $40 per gallon. Produced exclusively by Carolina Solvents, this oil-based acrylic includes superior UV protection and additives that repel mildew, fungus and insects, including termites. Technically known as TG 10, this low-VOC product retails exclusively to Green River Cabin customers.

Oil Stains

The last (and best) option for preserving a log cabin exterior is an oil-based stain. Nothing matches its strength, durability and attractiveness. As its name suggests, these stains are made with oil, not water. They key ingredient is linseed oil, which penetrates the wood to form a hardened exterior that blocks moisture, while enhancing the appearance of the wood grain. Additional ingredients are added to ward off mildew, fungus and insects. A UV protector is also included to deter graying.

The U.S. Forest Service agrees that “oil is best” among all stains. “Oil-base semitransparent stains allow the wood to ‘breathe,’ so the finish doesn’t blister or peel even if the moisture content of the wood is high,” according to the U.S. Forest Service. “The pigment in a semitransparent penetrating stain greatly increases the durability of the finish by absorbing much of the UV radiation that would otherwise degrade the wood.”

Oil stains typically cost more up front than other finishes, but that cost difference narrows when the customer considers the long-term value. Oils stains cost our customers about $85 per gallon, but deliver between seven and ten years of protection, depending on sunlight exposure.
Low VOC stains are now available that deliver the benefits of oil stains with a dramatic reduction in environmental and health risks. These stains are also mixed to include anti-fungal and insect repellent properties to further enhance their durability.

Final Thoughts

No matter what exterior application is chosen, it is imperative that the logs be dry and clean of any mold, mildew, sap, dust or any other surface debris that can interfere with the bond between the log and the finish. Just as important, it is always a good idea to apply two coats of finish to ensure a uniform and strong application. Additional coats are an option and typically darken the visible grain. Consult with your builder and the finish manufacturer to determine what application is best for the color and sheen you desire.