Log Cabin Primer
Consider these 14 essential things before committing to building or buying a log home.
Locating a site suitable for building your log home is step one. A professional realtor can help walk you through the selection, from access to water and sewer lines, soil evaluations and contacting the local building inspections department.
When you build new, you must acquaint yourself with covenants and restrictions on the structure's size and the building materials permitted.
And then there's the look and feel. Are you building for privacy, convenience or a great view? Once you've settled on the site and the finances, you'll be ready to select a design.
Are you building a weekend getaway or your primary residence? How many bedrooms do you need? Are you an active, outdoorsy family that needs lots of rooms for equipment?
All these questions, and many more, need to be answered well before you put pen to blueprint. List your priorities, such as big kitchen, privacy, porches, etc., and then work from there. And make sure that your design fits well with the size and terrain of your site.
Many types of woods work well for log construction. Consult with experienced log home builders and designers who can walk you through the pros and cons, as well as the individual characteristics, of specific types of wood.
You can certainly choose a combination of woods in your construction, depending on factors such as expected roof load, climate conditions, insulation requirements and simply the availability of certain woods. One of the key determinants will be shrinkage.
4. Log Shrinkage
Pardon the pun, but this is no small matter. Moisture in the wood slowly evaporates and shrinks the girth of the logs. This is part of the normal settlement process as a log home matures. Don't worry, it happens to everyone.
An experienced log builder can make the appropriate accommodations, such as using settling boards in window and door openings. These are pieces of trim sized to span the settling space. There are tricks to installing them, so get professional advice in advance. This is where experience really counts.
5. Dry Logs or Green Logs?
Green logs are those that have a moisture content of 19 percent or greater. They should be allowed to shrink about 3/4 of an inch for every foot, or about 6 percent. Generally they shrink more in diameter than in length. It takes time for them to settle completely, about five years as part of a heated home. But settling is dependent on many factors, including wood species, initial moisture content, temperature, humidity and log diameter, to name a few.
Expect dry logs to shrink as well, but not by the 6 percent standard as the greenies.
6. Handcrafted or manicured?
Milled logs have been put through a mill, planer or lathe to be cut into a specific profile. All the logs used in a milled log home are generally a uniform shape and they are usually air or kiln dried. Manufactured log homes use logs milled to strict tolerances, often tongue-and-groove, and come numbered and packaged with the materials needed to build the structure.
Handcrafted log homes are constructed by skilled craftsmen who will strip, shape and custom-fit each log.
7. Gaps Between Logs
Inevitably, as logs shrink, the gaps between them widen. That can make it awfully drafty -- time to get out your caulking gun. Make sure, however, that the caulk you choose is specifically designed for log homes. Technique is going to be important as well. For example, a lot of professionals will advise using backer rods in log joints to ensure that the caulk adheres. Coincidentally, they're also good insulators.
There are several types of foundations, including a concrete slab, a foundation wall to allow for a basement and a pier piling approach. The pier foundation is the easiest and the favorite of first-time log cabin builders.
Regardless of your approach, the tenets of a good foundation are its ability to safely support the load and its resiliency in the event of an earthquake or gale-force winds. The terrain, drainage and the soil character will factor in to your foundation approach. And don't forget to look into local building codes as well as the standard engineering practices.
9. Sill Logs
A few special considerations need to be addressed for these logs, which are the first logs above the foundation.
First, like all wall logs, they need to be at least 8 inches in diameter. Next, the entire bottom side of their bearing length will need to be flattened, and they should be set on a vapor, weather and air barrier – not in direct contact with masonry. Positioned at least 12 inches above the grade and firmly anchored, they will also need flashing attached or drip-cut to protect against water damage.
10. The Roof
For roofs that are constructed from logs or timber, the International Log Builders' Association says that you should only use "straight-grain, or moderately right-hand spiral grain material" due to its superior bending strength.
Constructing roofs with wide overhangs will protect the log beams and walls of the house, depending on the height of the wall. The roof beams that extend outside of the structure need special protection from the weather and insect infiltration.
11. Plate Logs
Plate logs, which should be made of straight-grained logs, are those that are at the top of each wall. The roof frames rests on these. Because they are prone to twisting, special precautions must be taken to firmly secure plate logs.
"Square notches and lock notches can provide restraint, as can any number of methods using bolts, threaded rod, and pegs," according to the construction standards of the International Log Builders' Association. It's also a good idea to permanently seal ceiling vapor retardant to the plate logs.
The rule of thumb when it comes to constructing a fireplace is that no combustible materials should be closer than 2 inches to a masonry chimney. That includes the log walls.
You also have to make adjustments for settling. As the log structure settles, the roof will lose elevation while the chimney stays at the same height. Make sure there is enough flashing to protect against water and weather even after the structure has fully settled.
13. Log Walls
There are, of course, several materials standards to follow as you construct the walls of your log home.
Basically, you can use green or dry logs, though you should be aware of their different structural properties and shrinkage expectations. Your plans will have to address that right at the top. Also, make sure you are aware of the grains of the wall logs, with particular attention to recommendations for using green logs. And remember, all your wall logs must be at least 8 inches in diameter. Lastly, strip the bark off to help prevent insect infestation.
14. Log Extensions
The the parts of logs that extend beyond notched corners are often called "log overhangs" or "flyways." If they are very long and not protected by roof overhang, they are prone to decay. If they are too short, they are prone to cracking.
Interior log extensions are those that project inside a building, and exterior log extensions extend toward the outside of a building. The stability of a dovetail corner does not depend upon log extensions and is not susceptible to having wood split off, so it's exempt from any minimum length requirement.