Log cabin repairs

What’s involved when a log has rotted? Since each log is structural, will repairs be a nightmare?

I know you’ve heard it before—a deck being built without flashing—but this time the home is a log cabin. I’ve already discovered some punky wood and that’s not even under the ledger, just in the adjacent area. What’s involved when a log has rotted? Since each log is structural, it looks like it’s going to be a nightmare to replace any of them. Is there a way to replace just some of a log?

Log cabins are obviously very different than stick-framed houses, but the same cautions about water intrusion still apply.

Improperly attached deck ledgers for decks will lead to rot.

Once you’re stuck with the problem, the best solution may be to call an expert. Restoring a log house is not exactly a beginner’s project.

I called Peter Caron, an Edmonton, Canada, expert who specializes in log buildings. Almost all of his work is on historic buildings, some of them dating to the18th century.

In short, you may be able to replace part of a log. But much depends on the extent of deterioration and where it’s located. And that’s not easy to assess without a site visit.

How to start

Start by taking core samples

Caron’s first step would be to drill a series of holes in the suspect log to find out how deep the rot goes.

Up to one-half the thickness of a log can be refaced (not as much in areas where structural loads are great).

Caron removes all rotten wood and adds a preservative treatment, such as boron rods for the sound wood that’s left. A new face can then be attached with stainless steel screws or bolts. Fastener heads can be concealed by counter-boring the new piece and inserting wood plugs.

Caron avoids epoxy if he can because he thinks the repair tends to trap moisture and lead to more rot in the future.

If this all sounds painless, think again. “It’s easier said than done,” says Caron, “but it’s doable.”

Replacing all or part of a log

If repairs are more extensive, the next step up in complexity would be to leave the ends of a log in place and splice a new piece in the middle.

In this case, Caron through-bolts 2x4s on both sides of the wall to stabilize it and keep logs aligned.

Whole-log replacement may require jacking part of the wall up to make room for a new piece. Caron inserts 1/2-in. steel plate between logs and places hydraulic jacks on both sides of the wall at each plate to do the lifting.

Jobs are made more difficult by interior finish that may have to be removed and by doors and windows, whose operation might be affected by the repairs.

Keep deck ledgers away from the building

Then there’s the old deck ledger problem.

In a stick-framed house, the wall can be protected by flashing that’s tucked behind the siding and bent over the top edge of the ledger. Water sheeting off the wall is directed away from the building.

It gets a little tougher with a log house.

Which leads to Caron’s suggestion that the deck not be attached to the wall in the first place. By making the deck free standing, there’s no way for water to be trapped against the wall of the house.

If attach you must, you flash the intersection by cutting a horizontal saw kerf into the log above the ledger, inserting the top edge of the flashing into the kerf and sealing the seam with caulk.

But log houses move around a lot, and the caulk may fail in time. This isn’t a technique that Caron would favor.

“Water in, water out,” says Caron. “That’s the key.”

Scott Gibson is the former editor of Fine Woodworking magazine, and a former editor at Today's Homeowner and Fine Homebuilding magazines. He is an avid and accomplished woodworker and carpenter.