“Chinking” is now commonly thought of as a water-based, synthetic polymer sealant that is textured like mortar and has considerable elasticity and flexibility. Twenty years ago “chinking” was generally thought of as Portland cement-based grout that was applied to the joints between logs, reinforced with metal lath. The new chinking products, such as Log Jam, far outperform the old type of chinking. Chinking
can be used in most places where caulk would be used, but chinking is
more commonly used in large joints between logs and when the building
owner wants the nostalgic look of old-fashioned, textured cement grout. You do not “have” to use backer rod (which is a type of “bond breaker”). But, if backer rod is not used wherever it is appropriate to do so, then the chances of experiencing a premature sealant failure are very greatly increased. Backer rod allows any sealant applied over it to perform much better than without it. Here are the reasons: 1) Backer rod insures that the sealant is adhered only to the two opposite sides of the joint being sealed – delivering what is called in the industry “two-point adhesion”. 2) Two-point adhesion permits elastic sealants to much more easily stretch – without any concentrated points of stress developing across the full width of the sealant bead – as the joint moves, over time, in response to temperature and humidity changes in the wood (or other material). 3) Backer rod prevents what is called “three-point adhesion” which occurs when the sealant is adhered to the opposite sides of the joint and to rigid material in the rear of the joint. When this occurs, concentrated forces are applied to the back of the sealant bead, usually leading to very early failure (with tearing of the sealant or the substrate). 4) Backer rod 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, premature “adhesive failure” is usually the result, and much sealant can be wasted. 5) Backer rod (especially the round types) greatly favors the development of “cohesive failure” – if failure is inevitable (due to extreme movement or very rapid movement that occasionally – but routinely – occurs with “maverick” logs or the interior surfaces of logs as they go through their first winter with warm, dry air from a furnace). When such “cohesive failure” does occur, it is relatively easy and inexpensive to repair by just cleaning the exposed surfaces that have torn down the middle of the joint and applying additional sealant (and most sealants do adhere well to themselves – but not all, which makes it important that you investigate this aspect of any sealants you may be considering using). Without backer rod, “adhesive failure” is typically the result, and usually the entire bead of sealant needs to be removed, with the applicator simply starting over. 6) Backer rod usually adds additional insulation to the surface of the wall to help reduce heat loss or gain. 7)
Round types of backer rod should be used when the logs are relatively
“green” and are subject to significant shrinkage and movement.
Round backer rod provides the most ideal sealant geometry for allowing
the greatest overall movement capability of all sealants and it also favors
cohesive failure if the movement becomes so extreme that failure is inevitable. Log Jam, Log Builder and Conceal are very similar in their chemical composition. The primary difference is the type of filler used in each respective product. Log
Jam uses a system of granular particles that imparts a relatively rough
surface texture. It is designed to simulate old-fashioned cement mortar. Conceal can best be described as a cross between Log Jam and Log Builder. It exhibits a medium texture that is designed to blend in with the surface of the wood. All
products establish high adhesion to various surfaces, including, of course,
clean wood and wood coated with compatible stains or paints. All products
are very elastic, accommodating a great deal of underlying movement without
cracking or pulling away. Conceal exhibits a little higher performance
than Log Builder and Log Jam in terms of adhesion and movement capability.
Log Jam exhibits higher performance than Conceal and Log Builder in terms
of insulation value and fire resistance. Yes,
but the following rules must be followed: A
variety of tools and techniques can be used in apply chinking or caulking.
Most applicators use foam brushes, steel trowels or plastic trowels. In
any case, it helps to lightly spray water on the surface of the material
immediately before brushing or troweling. While still wet, all three products can be cleaned with water while on hands, tools or surfaces. Once the material completely dries it is much harder to remove, and often needs to be cut or scraped off. If the material dries on your hands, you can usually remove it by just rubbing your hands together and it will roll up and off the skin. 7. Should I caulk my new log home now or in a year
or two? If
not for the impracticality of it, it would be great to allow the logs
to completely acclimate themselves to their new environment and undergo
the majority of their likely movement before sealing the building. But,
moisture and air leaks need to be controlled as much as possible right
from the get-go. So, apply the necessary caulking now – in accord
with all appropriate methods – and plan on performing a little repair
work over the next year or two as the foundation, roof system and walls
settle into place. “Linear
feet” is simply the length, in feet, of the joints (i.e., the gaps)
between the logs or the length, in feet, of the checks on the house that
need to be caulked or chinked. You can measure or develop from blue-prints
what the perimeter length is of your house (sometimes including the log
tails at the corners if these projections will be caulked or chinked).
You then determine how many courses of logs you have and multiply the
number of courses by the length of the exterior perimeter of the house.
If there are large areas with windows that will significantly reduce the
lineal footage of joints, then this – and other similar circumstances
– will have to be taken into account as well. Yes, most stains can be successfully applied over Log Jam, Log Builder and Conceal. However, it must be noted that the appearance of stain applied over chinking or caulking will almost always be different than the appearance of the same stain applied over wood. This is because of the differences in color and surface texture between such sealants and wood. So, before applying a stain to a large area where the stain is being applied to both sealants and wood, be sure you test a small area to confirm whether or not the appearance will be acceptable. Also,
it is important to note that many (but not all) stains are based on resins
or polymers that, when dry, are quite rigid and hard – far harder
and far more rigid than either Log Jam, Log Builder or Conceal. This can
lead to problems later as the chinking or caulking tries stretch to accommodate
the inevitable movement that continually occurs between logs due to changes
in temperature and moisture. Because the rigid coating cannot move nearly
as easily as the sealant, it builds up localized areas of stress and can
cause the surface of the sealant to develop shallow surface cracks, which,
while not normally affecting the overall sealant performance, can lead
to an unappealing appearance. It
is difficult to keep maintenance coats of stain off chink lines. You can
brush on the stain and attempt to keep it off the chinking, but that is
a time consuming effort. Another option is to spray the stain, back brush
it into the wood, and then come back over the chinking with a product
like Brushover. Brushover is our textured, elastomeric coating matched
to our Log Jam colors that you simply paint over the chink line to restore
the original color of the chinking. Log Builder is the leading caulking product in the log home industry. It has tremendous adhesion to all types of wood and is extremely elastic. While Sashco’s Stacker caulk can be used for this application, Log Builder will perform even better. |
Log Home Resource Center
1083 Highway 65 North
Greenbrier, Arkansas 72058-9321
1 (800) 441-1564
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Same Day Shipping The Log Home Resource Center offers same day shipping to your home, workplace or jobsite from Tennessee, Arkansas, and Colorado. Ask about our free freight program. Insect Control See our ACCESSORIES SECTION for the carpenter bee kit. Please call us if you have any questions. Bandsaws We have high quality bandsaws by Hudson. See Our BANDSAW PAGE for details.
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