Backer Rod FAQs

  • Q: Can I use anything other than backer rod or Grip Strip as a bond breaker?

    A: Yes! Clear packing tape (or any other kind of mylar tape) is also a common form of a bond breaker. If you are already at the desired depth, just place a piece of tape over the back of the joint and apply your caulking or chinking. You can also use duct tape or polyethylene tape (like Poly Masking Tape).

  • Q: Do I have to fill all the tiny cracks?

    A: It is good practice to seal with caulking or chinking (and backer rod) checks and cracks that are 1/4″ wide or wider, especially on the upper curvature of logs. Prior to sealing them, make sure to apply a good wood preservative (like Penetreat) to prevent insect and fungal damage. The very small micro-checks that are barely visible can usually be sealed adequately with whatever stain is applied to the surface of the logs. The most problematic checks are the “in-betweeners” – smaller than 1/4″ and larger than the micro-checks. Other than applying some wood preservatives to these types of checks, there is no really good way to treat these types of checks yet.

  • Q: Do I have to use backer rod when chinking?

    A: Yes. In order for the chinking to expand correctly, it is necessary to have some sort of bond breaker applied. If the joint is not very deep (less than 1/2″), clear packing tape will do the trick. In addition, you need a bond breaker behind the chinking to maintain the warranty on the product.

    When movement is known to be minimal (as with many older homes that have undergone the majority of their shrinking) using backer rod is still best, but usually less critical.

  • Q: Do I need to chink or caulk my “chinkless” style log home?

    A: Yes, at least in some areas – if not now, then later.

    Here’s why: Often, log home manufacturers design their homes to fit tightly together – no chink line is required. This is a look that appeals to many customers. Generally, when the logs are stacked, an “internal” seal is installed (either a bead of caulking between the logs, a butyl tape, or something similar) to insure a water – and air – tight home.

    Then, nature takes its course. As the logs dry out to their final moisture level, they move. This movement sometimes breaks the original internal seals between the logs allowing cold air, bugs, and water to come into the home. It is difficult to tell exactly where the seal is broken, so spot repairs are sometimes not effective. It is at this point that some homeowners choose to caulk the home between log courses to fully seal it up. Conceal is an ideal product for caulking these joints because it is textured and matched to the popular stain colors out there. So the Conceal caulking is truly “concealed” to insure the desired “chinkless” look.

    Also, as the logs dry out checks will appear and get bigger. These checks (on the home’s exterior) will need to be treated with Penetreat to prevent rot, stained to prime the inside surface, and then caulked (using backer rod behind the joint). Caulking these checks is essential to preventing rot, prolonging the life of the stain, and keeping water out of the home.

  • Q: How should I treat my checks?

    A: First make sure that the check is clean and free of any unsound wood fibers. This generally means sanding the area. Next, insert a backer-rod or some form of bond breaker in order to get the joint to the proper depth. Apply the caulking with a high-quality caulking gun (either bulk loading or cartridge style). Lastly, tool or smooth the caulking into the joint, making sure it is flush with both top and bottom surfaces.

    Refer to the data tec application instructions for the specific product your using for more in-depth information.

  • Q: I have a full scribed (“chinkless”) log home. Do I need to caulk?

    A: Yes, at least in some areas – if not now, then later.

    Here’s why: Often, log home manufacturers design their homes to fit tightly together – no chink line is required. This is a look that appeals to many customers. Generally, when the logs are stacked, an “internal” seal is installed (either a bead of caulking between the logs, a butyl tape, or something similar) to insure a water – and air – tight home.

    Then, nature takes its course. As the logs dry out to their final moisture level, they move. This movement sometimes breaks the original internal seals between the logs allowing cold air, bugs, and water to come into the home. It is difficult to tell exactly where the seal is broken, so spot repairs are sometimes not effective. It is at this point that some homeowners choose to caulk the home between log courses to fully seal it up. Conceal is an ideal product for caulking these joints because it is textured and matched to the popular stain colors out there. So the Conceal caulking is truly “concealed” to insure the desired “chinkless” look.

    Also, as the logs dry out checks will appear and get bigger. These checks (on the home’s exterior) will need to be treated with Penetreat to prevent rot, stained to prime the inside surface, and then caulked (using backer rod behind the joint). Caulking these checks is essential to prevent rot, prolong the life of the stain, and keep water out of the home.

  • Q: My chinking / caulking is torn. How do I fix it?

    A: Repairing torn chinking is really rather easy. First, use a razor knife to slit the chinking a bit further and release pressure on the bead. Then, clean the surface by wiping it down. Gun chinking over the torn area, tool the chinking feathering it out onto the exisitng chinking in the joint. If no backer rod was applied, you may need to cut out the torn area, install backer rod, and then follow the remaining steps as noted above.

    Now the question is, why did this happen and how do I avoid it in the future?There are a number of reasons why chinking or caulking can tear:

    a) The chinking / caulking line is too small for the log diameter. In general, the sealant should be 15% of the diameter of the log. (i.e. a 10 inch diameter log should have a 1.5 inch wide bead installed.) If you choose to go with a smaller bead for aesthetic purposes, you’ll need to do at least some repairs until your home is done with the majority of its shrinking and aclimating to its new enviroment.
    b) Improper application. Be sure you’ve followed the application instructions set forth in the data tec informational brochure.
    c) There are generally a few “maverick” logs that have a higher moisture content than the majority of logs used on your home. Typically, once the mavericks have dried and caused their damage they don’t move much after that and the repairs are quite durable.

  • Q: What are checks? What do I do about them?

    A: The word “check” is another way of describing the cracks that develop in inpidual logs. Most checks develop within the first one to two years after construction of the home, caused by the home drying out.

    Checks generally form along the grain of the log and can range in size – they can be tiny hair-line cracks up to 2″ or wider. Sometimes, but not often, they can appear in a spiral fashion, swirling around the log. Checks should be caulked if they are over 1/4″ wide and if they are either on the upward curvature of the logs or if they spiral into the home.

    In order to fill the checks, make sure that they are clean and free of any unsound wood fibers. The easiest way to ensure this is to sand the inside of the check, then wipe it down with a damp cloth. It is critical to determine that the moisture content of the wood is below 19% in order to minimize further log movement and reduce the occurrence of blistering in the caulk. Insert backer rod or some form of bond breaker to the proper depth (between 1/4″ and 1/2″) and then apply a bead of caulking into the check. Finally, tool the caulking smooth so it is flush with the log.

    Read the data tec information sheet for the product you’re using before doing any caulking to ensure you’re applying it properly.

  • Q: What can I do in the planning stage of my home to minimize maintenance later?

    A: The best thing to do, first and foremost, is your homework! Don’t overlook the important things:

    – As much as possible, locate your home on a site that affords some protection for the log walls from the weather.

    – Construct roof overhangs that are wide (like 2-3 feet) to protect the walls from moisture, wind & provide a sort of “sun shade.”

    – Keep the bottom course of logs at least 18” above the ground

    – Plan your landscaping so that sprinklers do not splash on the log walls. In addition, shrubs and mulch should be kept at least 2 feet away from vertical surfaces.

    – Find a log home supplier who uses a good design for the joints between the logs so that the joints can accommodate backer rod (which allows the caulking or chinking to perform as designed).

    – Apply wood preservatives as early in the game as possible, such as Sashco’s Penetreat or TimBor. Wood that has been pressure treated with borates (like Penetreat or TimBor) are preferable.

    – Make sure all the exterior finishing products that will be used (such as wood preservatives, stains, caulking and chinking) are all compatible with one another, and work as a system.

    – Make sure when it comes time to apply the exterior finishing products that the moisture content of the wood is below 19%. Use a moisture meter to be certain! Also ensure that the surfaces are very well cleaned by media blasting or vigorous power washing, and the contractor understands fully how to properly apply each of the products to be used. (This means getting very detailed quotes from the contractors you are considering using for the job.)

    – Thoroughly treat the log ends with borate wood preservatives, such as Sashco’s Penetreat. This means soaking the log ends 2-4 times with Penetreat solution (with a brush or sprayer) to get as much borate carried as far into the log as possible. For the lower courses of logs it might also be advisable to install some borate rods into the logs about 6-8 inches from the cut end, especially if the home is in a wetter climate.

    – When finishing, plan to thoroughly seal the log ends with a water-repelling coating. Because the log ends absorb so much stain, it will probably require 2-4 coats of the coating to fully seal the surface and prevent moisture from being absorbed. The log ends that are most exposed to the weather should then be re-coated routinely (every 2-3 years) to make sure they are still maintaining their water-repellent properties.

  • Q: What is best for me – regular round backer rod or Grip Strip?

    A: The best type of bond breaker depends on the type of logs used on the home. Grip Strip is generally used on flat Appalachian style logs that are fairly dry wood. These are not as likely to undergo as much shrinkage due to the fact that they are milled and often kiln-dried before construction.

    Round backer rod can be used in almost every other joint style. The round nature of the backer rod allows the caulking / chinking to adhere well to the wood, while the slightly thinner layer in the center creates the ideal hourglass shape, which allows the material to be a bit more flexible. This also makes it so that any failure due to extreme movement will generally split down the middle of the bead line, which is easier to fix.

  • Q: What is the difference between chinking and caulking?

    A: “Chinking” in the log home industry has come to mean an elastic sealing material that looks like the old-fashioned Portland cement-based mortar in color and/or texture, used to seal the joints between logs. Chink lines can be fairly narrow or pretty wide. Backer rod or bond-breaking tape should always be used in back of the chink line in order to provide 2-point adhesion and allow the chinking to expand and contract to the maximum possible degree. Log Jam and Chinker’s Edge are both excellent chinking products.

    Caulking also generally has more elasticity than chinking products. Because of this, caulking works better in smaller joints (i.e. ¼” to 2” wide). Caulking can be used to fill the horizontal cracks (called checks), create a continuous caulking line between the log rows, or as a stacker during construction.

  • Q: What is the difference between open cell and closed cell backer rods?

    A: Closed cell backer rod is probably the most common form of backer rod. Unlike open cell backer rod, it repels moisture. Closed cell backer rod comes in a variety of sizes ranging from 1/4″ to 5” wide and can be used on both the exterior and interior of the home.

    Open cell backer rod is a little easier to install because it is soft and pliable. It absorbs moisture so it causes the caulking and chinking to cure faster. Open cell backer rod is generally used only on the interior of the home. When open cell backer rod is used on the exterior of the home, if the caulking tears in any spot then the backer rod may absorb moisture, creating an ideal environment for rot.

  • Q: What is the insulation R-value of the Chinking and Backer Rod?

    A: Sashco’s thermodynamic analysis of this question has revealed the following:

    a) A 9” pine log has an overall R-value of about 11.2.

    b) The overall R-value of Log Jam + Backer Rod + the dead air space between the lengths of Backer Rod is about 10.6.

    c) The overall R-value of a log wall combining chinked joints and the logs themselves is about 11.1.

    So, when Log Jam is properly installed with backer rod it has virtually no detrimental effect on the overall R-value of the wall.

  • Q: What’s the difference between backer rod and Grip Strip?

    A: Both are bond breakers, but backer rod is usually round and Grip Strip is trapezoid shaped.

  • Q: Why do I have to use backer rod?

    A: It’s necessary in order to provide the proper joint design – caulking or chinking adhering to only the sides of the joint, not the back where the backer rod is placed. This allows the product to stretch correctly.

    Backer rod also greatly helps control the depth of the sealant as it is being installed to insure that the optimum amount of material is put into place. If too little material is installed, premature “cohesive failure” can occur. If too much is installed, the sealant is wasted and your costs are greatly increased.

  • Q: Will your chinking or caulking products stick to Tyvek or other house wrap products? Does Tyvek and other house wrap products act as a backer rod or bond breaker?

    A: Yes, our products will stick to Tyvek and other house wrap, which means NO, those products won’t act as a bond breaker or backer rod. It’s usually best to tape over those house wrap products with clear packing tape to get the bond break you need, as well as smooth out an wrinkles in the house wrap that could telescope through the chinking or caulking.