Maintenance of Log Homes

Restoration, Protection and Maintenance of Log Homes by
Jim Renfroe

Builders and designers of log homes generally do a good job of anticipating shrinkage and settling. They offer help in construction techniques that are unique to log homes, like scribing drywall around logs, running electrical and plumbing chases. But when it comes to initial and ongoing care and maintenance of log homes, there is more bad information given than good.

The initial wood treatment is often a coating that like paint is designed for adhesion to the wood and offers little or no protection to the wood below the surface. These film building coatings can cause a multitude of problems until they are removed, or wear off. Many films are very hard, so when the logs move, the film cracks. Water gets between the film and the logs and mildew begins. The film becomes like a greenhouse, incubating the fungus and trapping water inside the logs. This process has contributed to wood rot bad enough to necessitate log replacement in as little as 10 years.

Another problem is the use of dead standing trees for log home construction. Some of these trees have been dead for so long, they have internal wood rot that has begun. Combine existing rot pockets with a film forming finish and you have a recipe for problems.

It boils down to this:
Once you cut a tree down or it dies, you cut off its abilities to defend itself against its natural enemies. Mother Nature’s job is to return all things to the earth, including dead trees. If dead trees become house logs, you have to be very proactive in your approach to treatment. The best treatments are borates because they have no smell or color and are virtually nontoxic to mammals. They can be applied by pressure treatment, dipping, by brush or spray, or inserted internally using solid borate rods. CCA is another highly effective wood preservative that can only be applied by pressure treatment.

I have had several calls recently from people buying their first log home. However, unlike many first time log home owners, these people are buying a log home that’s 10 years old or older. They want to know what they can do to cure the problems with their log homes and to make them look better. Many of the problems are purely cosmetic in nature. My usual response is that these problems are only skin deep on an un-maintained log home, and just below the surface layers of mold, mildew, dirt and aged wood, is beautiful pristine wood. You just have to use the right combination of chemicals and techniques to get there. I also help them inspect for internal problems like rot and insect attack.

I have seen some pretty bad looking log structures be transformed from grunge to glory with a little effort and so I know that it can be done. One house I was recently involved in was built in 1915. They had put everything from pentachlorophenol to marine varnish on this house over the last 80 years or so and it looked pretty bad. There were areas that never got direct sunlight and areas that got full sun. The homeowner’s hobby was restoring old cars and he knew he could do the same thing for his house. The old finish was stripped off, the old logs were brightened, some logs were replaced, others were treated with a borate based preservative, then it was stained with TWP® ® and chinked. Now the house looks like a million bucks and the homeowners are delighted.

The restoration process consists of 4 basic elements:

  • Surface Preparation
  • Preserving
  • Staining
  • Sealing

All four steps are important but surface preparation is the most involved, most critical and often the most overlooked. Lack of proper surface preparation is like not washing a car before you wax it. House logs need to be clean, bare and dry before you go too far, otherwise, you will end up doing it all over again because the new finish didn’t penetrate or in some cases adhere. Also, the best time to tackle a project like this is when the temperatures are above 60 degrees. Not only will the job go faster because of reduced drying times, but cleaners, strippers, stains and preservatives all seem to accomplish their respective tasks more efficiently in warmer temperatures. However, the process can be done in much cooler weather, it just takes longer.

Surface Preparation and Stripping
Stripping is not always necessary. As a rule of thumb, there are four circumstances that dictate when stripping is necessary: When there is any type of film or coating on the wood, When there’s a build up of old finishes When there is any area of the house where the old finish is peeling or cracking When there is a glossy finish on the house If the old finish is acrylic or latex, make sure the stripper you use is designed to remove it. Most strippers work well on oil-based stains and paints, but the latex chemistry requires a different stripper. If however the house has had penetrating finishes applied to it or it has never had anything applied to it, or if a gentle breeze blows bits of the finish away, you can skip the stripping process and pressure-wash instead. Usually, a log home will collect dirt on the top side of the logs and that can be easily rinsed away. A home will usually have a line of discoloration mid-log on the exposed areas and along the bottom few logs where rain water from the roof hits the ground or deck and splashes back. Corners and exposed purlins often darken or turn black due to mildew or mold growth. The damaging effects of the sun manifests itself in gray wood.

Cleaning the logs
Bleach and water with a little detergent has been a long-standing recommendation for cleaning dirty wood. It works pretty good, it’s pretty fast and it’s cheap. However, there are a few drawbacks to bleaching wood. One, bleach can destroy the cellulose in the wood when left on the surface too long. Two, some researchers tell me that bleach inhibits the wood’s ability to hold a finish. Also, while the wood will get significantly cleaner, it often still looks gray or an unnatural washed out color. The other drawback of homemade bleach solutions is they are very difficult to completely rinse from the wood. Remember the last time you got bleach on your hands? It’s hard to rinse off and wood soaks up a lot more than your hands will. Also, household bleach only remains active for about 15 minutes once it’s mixed with water, so you have to use it quickly. However, if you insist on making your own bleach solutions, use it quickly, rinse it immediately after the job is done, rinse it well, then rinse it again.

Prepared Cleaning Solutions
When you buy a prepared wood solution from your friendly neighborhood mass merchandiser, look for the active ingredient of Sodium Percarbonate, Sodium Hypochlorite, or Calcium Hypochlorite. These are all bleaches. However, most store bought products contain buffers to ease the wood damage and surfactants to help wet the wood quicker and allow it to rinse off easier. Also, when spraying bleach on a wall, start from the bottom and work your way up. This will minimize streaks, which are difficult to remove. If the wood is just discolored, and has no significant areas of mildew, look for a wood cleaner containing Oxalic Acid. This is a mild acid that restores much of the wood’s original color. It is especially good for redwood and cedar, which darken pretty quickly due to extractive bleeding. Oxalic acid based wood cleaners will also remove gray weathered stains, metal or nail stains as well as water stains.

Regardless of what you do, remember to protect your eyes and skin from contact with any chemical and be careful with ladders. Read all label instructions (before you begin OK?) and follow them. Also, wet down any plants or shrubs with water. Cover them during the application, then wet them down again as soon as you’re done. This will help prevent any damage that could occur to delicate plants that could be misted with overspray.

Pressure Washing
Pressure washing is a very efficient way to rinse off a stripper or wood cleaner. However, you must exercise extreme caution when using a pressure washer or you will cause damage to the logs and possibly force water through the logs to the inside of the home. Here are a few pointers for pressure washing: Use no more than 2500 psi Use a pressure washer that delivers at least 3 gallons per minute, preferably 4 gpm. Keep the tip of the spray wand at least 12 inches from the wood surface. Do not hold the spray in one place. Keep it moving back and forth along the grain. Start the spray with the wand pointed away from the wood and move it onto the log. Never point the spray pattern at your skin. It will puncture skin and mandate a hospital visit. Be careful on ladders with a pressure washer. The force may throw you off balance. Do not concentrate the spray in corners, around doors or windows and between logs. Move quickly past those areas. Always have someone stationed inside the house with towels and plastic prepared to catch any water coming into the home.
TWP® is a registered trademark of Amteco, Inc.

Fuzzy Logs
Wood is made up of lignin and cellulose. The lignin is the “glue” that holds the wood fibers together. It is the first part of the wood to get destroyed in the aging process. Therefore, if you power wash the house with incorrect techniques, like too much pressure, holding the stream too close to the wood or leaving it in one place too long, you can blow the lignin away. This will leave loose wood fibers, partially attached to the surface and mostly unattached, which look like hairy logs. Even with proper technique, there will likely be some fuzzies that show up on the wood. The good news is that these fibers sand off easily and do not indicate long term damage.

If there are visible signs of rot, they need to be addressed right away. However, you probably won’t be able to detect any decay visually. Rot usually occurs from the inside of the log and is not visible from the outside.

A simple technique to help you locate any areas of rot or decay is by tapping the logs with a hammer every few feet. Sound wood will have a nice resonate tone. Rotten wood will have a dull thud. The best preservative family for house logs are the borates. They are less toxic to humans than table salt, they don’t change the color of the wood, they have no smell and they poison the wood as a food supply to just about every wood destroying organism know to man, including decay fungi, beetles, and termites. However, there are limitations. Wood needs to be retreated about every 5 years when it is in contact with the ground. The wood needs to have some moisture to allow for proper diffusion and you must apply and maintain a water repellent finish over the borate treated wood to keep them from leaching out. Given these few limitations, Borates become very inexpensive insurance against a host of problems. Borates disperse into wood through a process called diffusion.

A moisture content of 20% or more is generally required for diffusion to take place. If the logs are dryer than 20%, then the borates will not diffuse much further than where they were applied. However, rot can’t survive in dry wood either. Applying a borate preservative is always a good idea in my opinion because it’s there in reserve if the logs ever get moist enough to rot, and it doesn’t break down or become inactive if the wood is dry. There are currently three types of borate preservatives on the market today.

Timbor, or Penetreat is a dry white powder that is mixed with water and applied to the wood using either spray, brush, injection or dip treatment. Since this article deals with restoration instead of initial construction and treatment of new logs, the only logical methods of application to an existing log home are spray, brush or injection into beetle holes or holes that you drill. Bora-Care or Shellguard is a concentrated form of Timbor, in a mixture of glycols solution that helps to promote diffusion in dryer wood. Impel Rods are a solid form of the borate preservative who’s use originated in Europe several decades ago. They come is diameters of either 1/2” or 3/4” and lengths of either 3” or 4”. They are inserted into holes you drill deep into the logs that either have rot or have the potential for rot. When the moisture reaches about 25% they begin to dissolve, releasing the highest concentration of borate preservative available. Each rod will treat an area about one cubic foot. It is a good idea to use Impel Rods in combination with the other borate preservatives as an “internal log treatment”, treating the inside of the log while either of the other forms of borate for the corners, open end grain and checks.

Wood Finishes
There are several hundred types of wood finishes and deciding which one to use is a confusing process. They all say the same thing because all are supposed to do the same thing, which is to protect the wood against organic growth, water absorption and UV damage. You can’t research these products by reading the brochures and talking to salespeople that get paid to sell you this stuff. Otherwise your decision will be based on the design and wording of the brochure or the salesperson’s ability to convince you that his is the best.

There are a few common denominators about all wood finishes. One is the solids content. Solids can be defined as active ingredients or what’s left in and on the wood after the finish dries. Solids are components like resins, binders, pigments, fungicides, etc. Most over the counter finishes contain less than 10% solids. Therefore, 90% of what is in the can dissipates into the atmosphere a few hours after application leaving 10% of what you paid for, to protect the wood. These low solids finishes are cheap and ineffective. Most won’t even last one year.

A high quality wood finish will contain at least 30% solids and the better ones contain over 60% solids. The disadvantage of these products is that they cost more per gallon and the dry time is usually longer. However, instead of having to re-stain your dream home every year, a higher quality finish will look good and protect the wood for 4 - 5 years between maintenance coats. The payback comes in labor savings, good looks and protected wood.

Texas A&M University has conducted extensive tests on wood finishes. They found that most finishes failed between 7 and 18 months of exposure. Of over 200 products tested, only three finishes offered a natural look for 2 to 5 years before refinishing became necessary. TWP® , Sikkens and Seal Treat II. Seal Treat II is no longer available. Sikkens is a film builder and we already learned about film builders. Charles Stayton from Texas A&M stated that “TWP® last about 5 years and may be the best way to achieve an attractive natural wood look.”

A natural wood finish should be maintained whenever there are visible signs that the wood is aging. Examples are discoloration between the top and bottom of a log on the sunny side of the house, or when the wood no longer beads water. This should be part of a walk around inspection of your home at least once a year. New wood does not accept a finish nearly as well as wood that has been exposed for a couple of years. However, it is important to apply a wood finish as soon as possible. The first application will not last as long as subsequent applications and may have to be reapplied in the first or second year. The key to keeping a home looking good is to have a finish that can be reapplied without extensive surface preparation. Film builders will break down sooner or later and require stripping or sandblasting. Therefore, I strongly recommend penetrating finishes. They look more natural and they are much easier to maintain.

The last thing to do is to seal areas of the home that allow air and water transmission. The most obvious places will be where water seeped in during the cleaning process. Other areas where leaks often occur are in the corner notches, around doors and windows and at the top of the walls. These should all be sealed from the outside, not the inside. There are many high quality caulks on the market and caulking is much less visible than chinking. Caulk is also a very good way to fill and seal checks or cracks in the logs that may collect precipitation and lead to rot. It is a good idea to fill each check with a borate based liquid before you seal it up. This will take care of any rot or decay that may be active in the check. Just because you have a few air or water leaks doesn’t mean you have to chink your home. However, any log home can be chinked and if the leakage is extensive, chinking may be a very good alternative.

Chinking is usually applied over a backer rod, which fills the opening and allows for greater elasticity. Chinking must be applied at least 1/4” thick and the bead width should be at least 1”. The chinking bead should be continuous, around every corner, and log joint on the outside. Butt joints can be caulked with clear or wood colored caulk so they don’t stand out as much. If you feel the need to chink, give considerable thought to having it done professionally. Chinking is a very meticulous process and if it’s not done right it will not perform. Also, spend some time with the chinking contractor and get him to teach you how to make repairs or fix minor splits that may occur.

In conclusion, log home restoration can be avoided with systematic and ongoing maintenance. If you’ve just purchased a log home that’s a few years old, then restoration should only have to happen once. After it’s done, maintain the wood in your home just like you maintain your body or your car. Remember, house logs are really just tree cadavers. Once a tree is cut down, it’s life support systems are discontinued, and there is a host of natural process that begin attacking the wood in a attempt to return it to the earth. It’s nature’s way of recycling. You have to take a proactive approach to interrupt these natural processes and postpone them for as long as possible. Wood can last indefinitely with proper care and periodic maintenance. Taking care of the wood you own is an investment, not an expense, and it’s smart money.