Chinking The Logs
When properly prepared and notched, logs were stacked such that they did
not rest against each other except at the notch. A crack or chink of one
inch or more was visible between the logs of a wall. Chinks allowed for
warping and expanding when unseasoned wood was used. They also permitted
builders to work with the irregular surfaces and natural tapers of logs.
As with notching, chinking was influenced by different cultures.
Chinking was a two-part process whereby two fillers were used to close
gaps (or chinks) between the logs. Daubing was the outer finish layer.
If maintained, they effectively sealed the interior from exposure from
the elements, intrusion from vermin, and pooled water on the tops of
The materials used for the rigid filler varied, and were merely a product
of local materials. Clay, stones, poles, wood chunks, and split wood
shingles have all been used. The soft filler served to fill small cracks
and crevices around the rigid fillers and provided a surface for the
daubing to adhere. Oakum, moss, clay, straw, paper, cloth, and even
dried animal dung were typical soft fillers.
Daubing was the final seal of the three-part process. Mortar was perhaps
the most popular daubing. It was comprised of solely clay, mud, or dung;
or consisted of a mix of lime and water. Binders included sand, hair,
straw, ashes, flour, sawdust, and shredded newspaper. Bark remaining
on the logs served as an excellent binding agent. Modern materials have
included cement, and even chicken wire or metal lath are a daubing key,
though all are unacceptable materials, being non-historic and incompatible.
NOTE: Although 'chinking' and 'daubing' clearly define the difference
stages of the three-part process, the two words are often, albeit incorrectly,
used interchangeably. Popularly, 'chinking' is used alone to describe
Cement and its various forms can do irreparable damage to log structures.
It has most popularly been used as the sole ingredient in chinking,
which in itself is historically inaccurate. Its density reduces uniform
breathability throughout a structure, causing areas such as logs to
become saturated with water - in effect taking in more water faster
than it can release it.
Chinking should be flexible, and it should never be stronger than
the material to which it adheres. By employing cement, a rigid, incompatible
chinking is being introduced; the logs bear the full brunt of any
seasonal movement and absorb the bulk of all water.
CAULKS AND SEALANTS
Caulks and sealants are soft moisture-impervious compounds; they have
little or no ability to breathe. Caulks should be used in locations
where movement is minimal. Sealants are designed to be flexible in
areas with anticipated movement; their elasticity maintains the integrity
of a joint.
However, these modern products are not suitable for historic log
structures due to their non-porous nature as well as being historically
inappropriate. Caulks and sealants, generally, have improved lately
to achieve colour stability, and resist ultraviolet rays and mildew,
but their impervious nature prohibits them from working with traditional
building materials, particularly wood.
There are several suppliers of commercial materials to use for chinking. These include:
Here is some info that we located from Mother Earth News. Some of it is the same as above but we thought we would include it anyway:
"In the old days, hog bristles, horsehair, hemp and other
tough plant fibers were incorporated into house plaster,
stucco and log chinking. Their length held the
amorphous fluid ceramic together during application
and afterwards when dry. Exterior surfaces of
"horsehair" plaster were (and still are) preserved and
interior surfaces kept clean and solid with frequent
applications of whitewash.
Earliest log cabins were chinked with what was
available -- simple mud or mud mixed with straw, as
done for eons in mud-wattle, adobe or cob wall
construction. Many old cob walls (and chinking jobs)
remain serviceable today after scores and hundreds of
years; some all-cob domed granaries and houses in
sub-Saharan Africa date back millennia.
Loamy soil is to be avoided for chinking, as its organic
content will shrivel and continue to break down, leaving
voids inside the chink that will initiate internal cracks
and lead to eventual breakdown. Look for river mud
with a high clay content, or dig down under dark topsoil
to lighter, more dense subsoil, or mine a wedge of
pure clay if you can find one. Mix with equal parts of
sharp, clean sand and enough straw to hold it together.
For hands-on information about how freestanding
cob-walled homes are built today, read "From the
Ground Up," available by clicking on "Building" under
"Our Best Stories" on the home page. The same
principles apply to mixing and applying mud chinking to
logs. One thing: "point" -- or mold the outer surface of
-- your chink in an inside curve that ends a couple of
inches farther back on the bottom log than it starts on
the top log . . . so that rainwater dripping down from the
upper log will hit wood rather than the lower lip of chink.
Often the inside walls of the original log cabins were
plastered flat to look elegant. In any event, it's the thin
upper and lower edges of exterior chink that need
attention and repair most frequently -- to keep water
Mixtures of quicklime with mud and straw or animal
hair were tried but have not held up well for a century
and a half. In 1824, a British mason invented Portland
cement, which replicated Roman mortar and still holds
up after 2,000 years. It is made by heating a mixture of
clay and limestone (chalk) to burn off water content,
then grinding the result. Mixed with water and a matrix
of gravel or more sand, it rehydrates chemically and
hardens back to waterproof rock. Mixed with a pure
sand matrix, it becomes mortar that forms a
permanent, waterproof bond between stones or
ceramic, such as brick or block. Mixed with sand and
gravel it becomes concrete.
Both mortar and concrete mixes have been tried for
chinking -- either put in solid, mixed with straw, or in
inner/outer layers with straw or other porous material
in the middle. It is heavy and it cracks when water gets
under thin edges. Cracks can't be patched effectively,
as the continual motion of logs rebreaks it. It absorbs
water (without modern concrete-waterproofer) and
passes it through from outside to inner walls, where it
stains and forces off paint, plaster, wallpaper and
You are best advised NOT to use lime or Portland
cement in any chinking mix. It is monolithic; as logs
shrink and swell with the weather (and they all do) they
will pull away from the chinking, leaving space for cold
drafts to whistle in, bugs and varmints to enter and for
rain to work between chink and log . . . to freeze and
chip the former and pool and rot the latter. You will be
forever patching. Today you see mortar-chinked log
houses patched with new cement-mix, tar, caulks and
mastics, chewing gum and pine tar. Most such have
been painted long since and look awful.
If chinking of cement or mortar mix and sawdust or
whatever sets up at all, the core of it will last forever;
shaped as an "H" between two logs, it can't be
removed except with a jackhammer. Some long-ago
geniuses even inserted steel reinforcing rods (rebar)
inside solid-concrete chinking so you need a cutting
torch to remove it in sections.
In modern chinking systems, well-trained and
well-equipped specialist contractors place backer rods
of rigid or extruded expanded (poly) foam in the center
of the space. Then, using special trowels and
power-caulking guns and years of experience, they
apply a thick plastic (vinyl) coating over the seam,
inside and outside. It insulates well, adheres and
remains semi-rigid for decades, expands and
contracts with time and temperature, log movement
and shrinkage, comes in any color you want, will last
for decades with little or no upkeep, and is easily
removable with little but a penknife if repairs or
replacement are ever needed."