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Backer Rod & Chinking
Part-1
By Denise Carlson,
Customer Service Rep. |
As
the warm weather begins, its the time of year when we start
thinking about chinking our log homes. The first step of caulking
or chinking is applying Backer Rod. The Log Core will take
you through a two part series of Backer Rod and Chinking.
We will begin this series with backer rods of all types.
Backer Rod is a synthetic foam that comes in a variety
of shapes and sizes from 1/4" up to 5". The reason why Backer
Rod needs to be placed in joints is that it acts as a bond
breaker, which provides a surface that chinking won't adhere
to. Eventually, the chinking will free itself from the backer
and will move with the logs as they expand or shrink. Backer
Rod also serves by adding an insulation value and reduces
the amount of material needed.
Grip Strip comes in strips of 4-ft. lengths. Sizes
are available from 3/4" up to 5". It provides an excellent
fit with a flat working surface and is a closed cell product
that repels water. As a chinking applicator for a restoration
company for 7 years in Northern Minnesota, I have found this
material is the easiest and quickest to use. No tools are
necessary and it follows with the curvature of the logs. This
product really grips to the logs and stays in place.
Tri-Rod is
another backing material that offers a flat working surface.
This is polyethylene foam backer that is designed for round
logs. It is a triangular strip and is available in 6-ft. lengths.
It is a closed cell product also. You may need a spray adhesive
such as Touch and Seal or Foam Weld to keep it in place. When
installing the Tri-Rod around knots and curvature of the logs,
the backer must be cut out on the backside. This will keep
the backer from projecting out and will keep the chinking
uniform. This does take more time to install.
Dual Rod can be described as an open cell, extruded
polyethylene foam. Dual Rod is extruded to leave an imperable
shell to prevent moisture from entering the side. It is available
in a continuous length through 1-1/8"; larger sizes are available
in 6' lengths. This may be sold by the foot or case, and is
available from 3/8" to 4". Advantages of this backer are that
it is very flexible and is easy to install. Smaller sizes
are offered to fit those really tight joints. When choosing
a size, the diameter should be approximately 25% larger than
the joint because of the compressibility. Precautions to take
are not to puncture or stretch during application. This may
cause out gassing. In smaller joints a blunt tool may be needed
to push backer further into the joint to allow the required
amount of chinking. This material is easier to work with for
smaller size joints.
Closed Cell backer rod is a closed cell polyethylene
round foam that also runs in a continuous length. It is sold
by the foot or by the case from 1/4” up to 4". Compared
to the Dual Rod this backer is firm, but just as easy to install.
Again a blunt tool may be needed to push backer deeper into
the joint to allow the required amount of chinking.
Open Cell Backer Rod is easy to work with also. It
is soft and compresses to fit most size joints. This product
is breathable which allows for a faster cure, but recommended
in the interior. This is because it will absorb water. If
used on the exterior, only put in the amount of open cell
that you think will get done in one day so the exposed backer
will not draw in moisture. Note: the use of a blunt tool when
installing backer rod to the exterior logs will prevent punctures
to the surface of the rod and minimize chink blistering caused
by trapped water vaporizing under direct heat from exposure
to the sun.
For smaller joints where backer rod can not fit, but yet there
may be a gap, a mylar tape or strapping tape may be used.
This too will serve as a bond-breaker to allow the material
to release itself from the tape and move with logs as they
settle and shrink. If applying chinking over old mortar, a
bond-breaker tape should be applied as well. Packing tape
or duct tape are two examples that will work for this situation.
If the
backer seems to keep popping out, a smaller backer or a different
style of backer is needed. You should never have to nail Backer
Rod to keep in place. The most common mistake about choosing
Backer Rod is that folks choose a backer that is too big for
the joint. When this happens, the backer keeps coming out
or you are left with a chinked joint that is larger than it
needs to be. I recommend to take advantage of the samples
we have to try different styles and sizes. Keep in mind that
you may require a number of different styles and sizes for
your particular project.
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Backer
Rod & Chinking Part-2
By Debbie
Bassett, Sashco Products |
Chinking a log home is not a difficult process. Once
you get over the awkwardness of learning how to “gun
the product” onto the logs and then get the “feel”
of tooling the product you will pick up speed and find satisfaction
in having a part in finishing your home. This article covers
the basics of how to chink a log home, but before starting
your project in earnest, request and read a data:tec sheet
that goes into greater detail.
Proper Joint Design Last month’s article briefly
touched on the reason why backer rod is needed—to serve
as a bond breaker. The following illustrations graphically
depict why 2-point adhesion is so important for the performance
of any chinking or caulking product. Synthetic chinking is
formulated to be flexible, but as the above drawings demonstrate
it can fully flex to absorb log movement only if a bond breaker
is installed down the center of the joint.
Surface Preparation For chinking to establish
good adhesion to the logs, they must be clean—free of
dirt, pollen, uncured oils, sawdust, and other loose materials.
The surface temperature of the logs should be between 40°-90°
Fahrenheit. The liquids in the chinking “wet out the
surface” of the logs so that the chinking can establish
good adhesion. If the log surface is colder than 40° the
wood pores tighten up not allowing for proper wetting out
of the surface. Conversely, when the wood temperature is higher
than 90°, the liquids evaporate off too quickly, adversely
affecting adhesion.
Most people like contrast in color between their chinking
and their stain; therefore, staining prior to chinking is
necessary to achieve this look. It is also easier to tool
chinking if it is applied to a stained surface, but you must
be certain that the stain and chinking are compatible, and
that the stain has had sufficient cure time.
Many stains on the market contain waxes and stearates that
can interfere with adhesion of chinking and caulking. Usually,
companies that manufacture both chinking and stains make certain
that their products are compatible, and attempt to enhance
their stains for even better adhesion of their chinking and
caulking products. If your chinking and stain are manufactured
by 2 different companies, call and ask if testing has been
done for compatibility and request a copy of their test results.
Application Chinking is packaged
in 5-gallon pails and quart tubes, although for larger jobs,
5-gallon pails are more economical. When using 5-gallon pails
there are a number of application methods that can be used.
You can use a trowel, grout bag, bulk loading gun, or a commercial
pumping system that pumps out the chinking material in a continuous
flow, making it easier to apply.
There are a variety of different sized nozzles available in
both round and slot styles. For smaller beads, a round style
nozzle works well but for wider joints the slot style nozzles
are the only way to go.
In selecting your nozzle size be aware that the depth of the
bead of caulk should be ½ the size of the width of
the joint, but never thinner than a ¼” or thicker
than ½”; i.e., for a joint 1” wide the bead
depth should be 3/8” to ½”.
Apply the chinking material down the center of the joint,
over the backer rod and overlapping slightly onto the surface
of both logs. Only apply enough product down the length of
the log that you can reasonably tool before it starts to skin
over. As you become accustomed to tooling you will be able
to run longer beads.
Tooling There are as many tooling implements out there
as there are chinkers! I prefer the polyethylene foam brushes
available in any hardware store or lumber yard but I have
seen folks tool with rubber spatulas, paint brushes, putty
knives, trowels, and even metal spatulas cut down with wire
cutters to the desired width. The secret is finding the tool
that works best for you. You will also need a pail of clean
water, a sponge, and a spray bottle filled with clean water.
To speed up the tooling process, have several foam brushes
on hand. As soon as one picks up too much chinking and starts
to drag instead of gliding over the surface, throw it into
the water pail and continue on with a clean brush. A mixture
of 1 part denatured alcohol to 2 parts water can be used for
misting chinking when the temperature is over 70°. If
you are working in the sun and the chinking is skinning over
too quickly, straight alcohol can be used. When the temperature
is lower than 70° the alcohol is not necessary.
Using a damp polyethylene foam brush, holding the foam portion
parallel to the bead, gently press the bead into place. You
don’t want to drag the foam brush down the bead but instead,
section by section press the foam brush against the bead.
The next step is the actual tooling. Using the spray bottle,
lightly mist the chinking with water to allow the brush to
glide over the surface. Do not apply too much water, or the
latex in the chinking will run down the logs. If this happens,
just wipe off with a damp sponge or rag. The idea is to smooth
out the ripples caused by gunning, but most importantly, to
feather the bead out onto the top and bottom logs at least
¼” so that the chinking is tooled tightly to the
log surfaces.
Clean-up and Disposal To properly dispose of unused
chinking material, it is good practice to understand and follow
all of your state and local regulations on clean-up and disposal.
Do not dispose of chinking material in drinking water supplies.
However, for easy clean-up water may be used for cleaning
hands, surfaces and equipment. Toxic solvents are not required
for chinking material clean-up.
Warning! As you finish your chinking and stand
back to admire your work . . . ugh! Blisters! Blisters are
a phenomenon commonly found after applying chinking. They
form when moisture from the chinking accumulates in voids
beneath the bead and the heat from the sun causes the blister
to appear as “bubble” in the chinking. To avoid
these blisters, use a white tarp to shield freshly chinked
walls from the sun. If this is not possible, keep a close
eye on the chinked wall for the first 24-48 hours. If a blister
pops up, just puncture a hole in the middle of it and gently
push the chinking back into place. Then after 3-5 days you
can repair the blister by applying a small portion of chinking
material into the hole.
Cure Time After the chinking process is completed,
allow it to cure for one week if you will be painting over
it with oil or latex paints, total cure-through is 28 days.
Just one last suggestion that I picked up from a professional
chinker: Hang a small board with several beads of the chinking
in a conspicuous area with a sign inviting people to satisfy
their need to touch. Hopefully, this will keep them from satisfying
their curiosity on the chinking courses of your home!
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