If your log home does not use gaskets between it's logs, then log chinking is a sure way to increase it's thermal efficiency saving you heating and cooling costs. Also chinking will seal places where insects and rodents can live or use as an entry point to your home's interior. The results can be very remarkable by giving you a much more livable home.
Full Scribe Exterior Logs
The logs on your home fit very tight together when your home was first assembled. However they most likely each had a different moisture content and when they dried to a uniform percentage, their shrinkage left a lot of gaps between the scribes. Chinking will seal the logs which gives a finished look and makes your log walls draft free and water tight.
Ridge Pole and Purlins
Many log homes use a ridge pole and purlins as part of the roof system. These are large diameter logs with a wood frame around them on the gable ends. When these logs shrink, fairly large spaces open up between the frame and log. Here is a prime area for bats to inhabit and cluster flies to gain entry. This is always a worthwhile area to look at.
When your home was built a settling space was left above the doors. Without the space, as the logs shrink they would hang up on top of the door frame and your door wouldn't open. Usually fibreglass insulation was loosely put over the door and the casings installed to seal it. We remove the casings, remove the fibreglass and replace it with rigid insulation and chink. Another entry point for drafts, insects and rodents.
Notches and Checks
Notches are the cut outs in the logs where they join to other logs. Due to log shrinkage these joints open up and are found to be some of the biggest sources of draft and in extreme cases rodent infiltration. Checks are found on the length of the logs and on the log butts. If the check is fairly large and extends into the notch it must be chinked and the checks on the log butts need to be sealed too. Both can harbour insects, rodents and are a common area to eliminate drafts
Same as the doors in your home there is a settling space above the windows. We use the same procedure as the doors. Also not mentioned we apply chinking to where the logs butt up to the window and door frames to eliminate drafts and provide an insect or rodent free seal.
I recommend chinking the exterior first and then if you want to make the logs more thermal efficient
have the interior chinked. Chinking both sides of the log creates a dead air space which slows air's ability to absorb the heat or coolness from the logs by reducing the surface area it comes in contact with. This helps save on heating or cooling bills.
If you are currently living in a chinker style home you may have mortar or rope with quarter round boards stuffed between the logs. By removing these materials chinking can be applied to eliminate drafts and provide an air tight seal.
Unless you are building a chinker style log home, I would recommend that you not chink the logs until they have reached a moisture rate of 6-10% depending on your location. This will take at least one heating season and maybe two if you have large diameter logs. A moisture meter will reveal the content or you could just about judge it by observing log movement by the drywall or the settling spaces.