Notches

Festive, cozy, and nestled in the forest — the log cabin is the architectural epitome of the holiday season. A well-built log cabin stays so cozy throughout the winter due to the watertight and windproof seal created in part by a notching system at the cabin’s corners. In “locking” the logs, notches help make traditional sealing materials of mud, clay, and straw (known as chinking when on the exterior of the cabin and daubing on the interior) more effective.

Notching systems boil down to four major types: the saddle, the dovetail, the butt and pass, and the corner post.

The saddle notch system originated in Scandinavia and involves cutting or scribing a rounded notch in a top log to lock it on top of the log below. The steeple notch is essentially a saddle notch cut in a “V” shape, and both the square notch and step and lock notch are further variants on this style.

The dovetail notch has a distinctive look and creates the tightest corner. It also requires the most skill. A full dovetail entails scribing at two sloped angles along both the top and the bottom of a log; this is what creates the “tail” shape. On a half dovetail, the only sloped angle is on the bottom of the log. The lock is weaker, but also more watertight than a full dovetail.

The butt and pass technique does not actually involve any notching and requires the least amount of craftsmanship. A long log rests atop a perpendicular long log, while a short log meets the perpendicular long log. No scribing is required; instead, the logs are fastened with pins.

The corner post method commonly uses a mortise and tenon system to secure horizontally placed logs to a vertical post. Logs also may be pinned or nailed in place.

Of all the notching techniques, the corner post and butt and pass methods are the least used. Dovetail and saddle notch systems are more common.

The images below show dovetail notching on the Alder Gulch school near Virginia City; a boy with his catch in front of a saddle-notched cabin at an unknown location; and a blend of notching techniques on a cabin behind a woman identified as Loo Siang in Virginia City.

To learn more about log cabin preservation, check out the USFS’ seminal guide on the topic, “Dovetails and Broadaxes: Hands-On Log Cabin Preservation": https://www.fs.usda.gov/.../1523-2802_Dovetails+Broadaxes...

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