Sealing Logs in TAR and CONCRETE... a Bad Idea ?

[Ramblin Randy]

Our family farm has a scenic log cabin/guest house that is "sick" and I'm VERY CONCERNED that if we do things backwards then moisture will soon lead to mold. Would you be so kind, using prior experience when possible, to steer us and lead us forward in making the right decisions.

Our cabin we’ve discovered is not original, it was probably a former barn that was trucked in and reassembled into a fishing cabin along the creekside in the 1940’s. It sits on a 15 degree slope, and has a very minimal foundation, and the backside logs touching the earth have rotted out due to poor rain water drainage. The bottom logs are 75-80% rotted out. The original plan was to “en-tomb” the rotted logs in concrete on the outside and underside leaving the interior log facing “as is” for cosmetics.

A well respected colonial restoration professional came to visit last month and gave his recommendations. He spent about 2 hours with us and the visit was one of the highlights of my summer of 2020. ( yea it’s been crazy here too ). With his permission I video taped the conversation as well. I’m curious to get a second opinion… wishing to compare your thoughts along side his.

At this very moment, and the clock is ticking because the concrete truck will be showing up soon, the lead on this project has reverted back to the original “entombing” the rotted logs in concrete. To prevent moisture, from weather fluctuations, it has been decided TO COAT THE DAMAGED LOGS IN TAR FIRST. Just asking, is this tar and concrete plan acceptable ?

[rckclmbr428]

Why not replace the rotted logs? That what I do.

[Ramblin Randy]

Why not replace the rotted logs? That what I do.

The Restoration Specialist recommended log replacement. Replace kind with same kind. Replace logs with black locust or oak logs. I have three local 3 lumber mills waiting for my call and specification. Note that our Restoration Specialist came to visit at no cost... he just wanted to look at our old log cabin.

A local builder with 30 years experience with old homes has recommended the tar and concrete course.

Dale Earnhardt is famous for the following: "Sometimes you win some, sometimes you lose some, and sometimes you wreck some". I fear that in 5 years all this concrete and wood sandwich will be one big mold and mildew castle.

[Shark]

Yeah that's what I'd be worked about too. The tar and concrete will not stop the rot only hide it.
Do you have a plan to keep water off it in the future? (Prevent the same issue down the road after repairs)

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[rckclmbr428]

The local builder is suggesting tar and concrete because he doesn't know what he's doing. White oak or locust would be the best route for replacement.

[rreidnauer]

I second the notion of tar and concrete method, as a poor choice.
I have some questions before I will say what course I'd likely take.
1) how big is the structure?
2) single story, or two?
3) in relation to slope, which side is the entrance on?

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[Ramblin Randy]

1) how big is the structure?
The main log cabin structure is roughly 20x20 feet and half is a bedroom and half a kitchen. Additions flank the north and south sides, an a porch on the east. The problem area is the west face.

2) single story, or two?
Single story cabin. The foundation is minimal.

3) in relation to slope, which side is the entrance on?
Entrance is on the far opposite side where the problem corner is. Problem area sits flush on a slope mostly of bed rock. Entrance is about 3 feet from doorway to ground.

[loghousenut]

I say pay the local more than he is worth and never let him on the build again.

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[rreidnauer]

OK, the additions and deck throw my first idea out the window. (which was to jack up the structure, pour a better foundation, and replace the first course logs) So, I think with that information, I would have a dozer come in and regrade the high side down, making sure to swale the grade to direct runoff to either side of, and away from the structure. I'd still remove the first course logs that are rotted, pour over the existing foundation a more robust stem wall, and install new logs. The most challenging part of the operation being, supporting that part of the structure while you perform the repairs. May seem daunting, but is quite feasible, and will last a lifetime. I don't think your current plan will solve anything, and is little more than a stop-gap fix to hide the problem until a later date.

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[Ramblin Randy]

Pull up and chair and listen in… you’re about learn something today. I wanted to hear some other’s opinions before I introduced the advice and wisdom from our preservation guru Douglas Claytor. Some of you probably know him as he is one of the leading repair specialist in the field of 200 year old glass pane window repair. He has attended work shops all up and down the east coast and has put his able hands to work as both contractor and as a volunteer in many historic preservations both public and private.

Doug on his visit first gave us the run down and history of our structure immediately telling us this cabin was reassembled. That was sad news because I can no longer tell people that George Washington probably slept here LOL. His structural advice was consistent and made sense and was in two parts. First was the process, which was used in many state projects repairs, was to always use the same materials that were originally used… so it’s best to replace the logs with some oak logs or better yet locust.

The most interesting knowledge he shared reaches into today’s building structures where we were informed about all the mold and moisture problems new housing is experiencing because the materials used today create air tight enclosures. In reality wood structures all need to breath and it’s now being considered to leave new homes without insulation in the walls and only insulate the floors and ceilings… leaving the structure to “breath”. My 100 year farm house has zero insulation in the wall and zero mold or milldue smells. I have one of the biggest wood stoves Fisher makes to over compensate LOL.

The second tidbit of advice given that day was to leave some vents in the foundation so that air can travel thru and under the home during rainy times. The vents could be blocked in the winter to keep the floors a bit warmer, or maybe just get some big rugs..! So there you have it folks… ventilation is key to your 200 year old structure as well as your home today. Will we put the stop on the concrete plan and do the job right only time will tell. I harken back to that tv commerial for Fram oil filters and how they used to warn us: “You can pay me NOW, or you can pay me LATER”.