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Everything you know, upside down: Log repair and replacement in backcountry shelters

August 16, 2011



Log repair and replacement for backcountry full scribe log shelters is a tricky and slow business. The building must be lifted in the air, the floor must be removed, and the new logs must be scribed to fit the courses above. Effectively, you are being asked to build a building upside down. When done by hand, with an eye for long term durability and a clean appearance, such carefully executed work can not be rushed.

AMC maintains ten shelters in Maine and New Hampshire, and of those ten, four are full-scribe native log structures, built between 1974 to 1981. Gentian Pond, built in 1974, is the first shelter that required attention, as the back corners and the front first log course displayed significant rot.

With logs cut to replace the sills well over a year ago, and funding from the Appalachian Trail Conservancy’s LL Bean Grants to Clubs, AMC Trails spent three weeks in July replacing four logs and the floor of Gentian Pond Shelter.

The technique we culled from our collective experiences in construction, foundation work, log repair, and previous projects such as the RMC’s Perch shelter. It was a team effort, with crew members from the backcountry caretaker program, the roving contract trail crew, and leadership from Sally Manikian (that’s myself), White Mountain Trails Supervisor Dave Salisbury, Roving Contract Crew Supervisor Kris Kebler, and Director of all of us, Andrew Norkin.



In addition to our prior collective knowledge, I spent a week in June on Montana’s Ninemile Ranger District in the Lolo National Forest learning firsthand from the historic preservation and restoration professionals from the US Forest Service’s Preservation Team. I learned invaluable techniques on how to fit logs into existing structures. For more information on the Ninemile’s historic preservation courses, ranging from crosscut saw maintenance to horsepacking to Leave No Trace Master Courses to log building work, click here. The courses are open to the public, and I highly recommend them. The photo on the left is from the Montana project.

For Gentian, the basic technique was to band the shelter together by attaching vertical 2”x8” pieces of hemlock to the inside of the building. This strapping providing structural stability for the shelter as it was lifted, as well as provided a place to jack off of. Once the floor was removed, we were able to attached the strapping to the interior walls, and slowly lift the building into the air, blocking the corners with three foot sections of 6”x6” cribbing. Removing the floor, lifting the building, cleaning out the silted earth and trash underneath, and cribbing it into place took the first week.

The second week was spent fitting the four new logs to the existing building. The trickiest log to place was the front log, as we had to account for the door frame as well as scribe it to fit the log above. The tools of the trade of logwork came in handy: a Veritas log scribe, a set of chisels in various sizes, sledges large and small, a chainsaw, and a large pile of wedges.

The final touch was just as tricky as the steps before, which was to build the floor. Matching dimensional lumber to square round logs is not easy. The flooring itself was also rabeted into the logs, so that the top of the floor meets perfectly the top of the front log and side logs. Building the floor, and the ladder to the shelter, took another week and was accomplished by the Field Coordinator Beau Etter Garrette and Mahoosuc Rover Ryan Smith.

I will let the photos speak for themselves. Thanks to the combined talent and effort of the Trails Department, Gentian Pond Shelter is open to the public once more.

Week I: Floor and log removal, lifting of the shelter
Last lunch on the old floor

Rotted back corners

Rotted front log, once the floor was removed.

Where’d the floor go?

Old dogs can’t learn new tricks, even when there no longer is a floor to sleep under



Attaching the 2″x 8″ pieces of strapping to hold the shelter together and also to jack off of

Strapping and cribbing in use.


Side log removed.


Front log removed
A shot of the interior with the back log removed.

Cleaning out the dirt and debris from underneath the shelter


The best find? Coins from the 1940s

By the end of the week, the shelter was cribbed into place at the desired height.




Moving the logs into place




Week II: Log replacement
We started with the front and back logs, which were the first course of logs to fit into the current structure. With the cribbing and jacks off set from the corners, we were able to maneuver the logs into place and work on them. Since the logs needed to be scribed and shaped to fit, being able to move them in and out to get the perfect fit was necessary.


Finishing the notches in the front log, using chainsaws and chisels.


Trimming the rotted ends off the logs that extended beyond the roofline, to prevent further rot


Back log in place.


Running a saw between the courses of logs carved a tight fit between them.


Squaring the sill logs to the centerline of the building.


Back corner almost tight in place.


Fitting the front corner.



Tight notches



The new logs in place



Week III: Replacing the floor
Matching the square ends of dimensional lumber to rough cut native logs took the majority of the third week, along with building a ladder. The shelter is now 6″ above the ground on footers, whereas before it was flush with the ledge. With a lack of air flow, dirt accumulated against the back of the shelter leading to the rot.



New ladder, customized to fit the front log.

New floor flawlessly meeting the front log.



Done.





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