Chinking Recipes

[Suebrook Farm]

Good morning. I'm about to start chinking a late 1800's log cabin restoration. I do not want to use synthetic. Can you give me some recipes? I've seen Portland and sand or Portland sand lime. What is the purpose of adding lime?

Thank you
Steve smith
Tyler TX

[Don P]

Lime adds plasticity, it makes portland more sticky. But... portland doesn't play well with wood. It tends to trap moisture and hold it against the wood. Those cement chinked cabins are not faring well, the same thing happened with cement plastered timberframes in Europe. Remember portland is a synthetic in the historical sense, it was not available in that time period, slaked quicklime was more commonly available, "slack lime". I've also run into clay and cobs, rocks and clay, etc but it tends to harbor insects where lime resists them and seems to draw moisture from the wood. Most restoration has moved more to straight lime renders with no portland. Check the NPS preservation briefs online, I'll see if I can dig up anything else.

Here's one method that looks good. The final coat looks tough but would help with water shedding;
LOG CHINKING, YE ALDE CALK, MEND THE GAP BETWEEN BRICK/STONE AND FRAMES - LimeWorks.us

This is some chinking in an old log house, chestnut splits and a lime based daubing.



 
Another shot in there, that is a lime based first coat, the whitewash on the walls also seemed to be lime based. That's a typical beaded floor joist for around here.


 

This is dolomitic limestone flakes out of the river beside this saddlebag cabin and a lime based mortar with river sand. The next joint up has split timber chinks and lime daubing.


 

Cob and daub, this one had clay, you can see some of the dust, all sorts of critter galleries in that. It had been covered in a poorly detailed portland chink job in the '70's that directed water in and held it, that caused a lot of trouble and replaced logs.


 

[kantuckid]

We watch the Barnbuilders TV show off our DVR and tend to speed walk our way through most episodes but enjoy the settings and old buildings and cast/crew members. Several of the regulars on there are from our immediate area which ads some to the shows appeal. It can get pretty repetitive though. 
One theme, as Dan mentioned above is that the cement chinking damages the prospects of the logs making it to today intact enough for re-use. Siding is of course another aspect of preservation along with roof overhangs and type of corner joints. 
At the Appalachian Museum in Norris, TN there are many old antique log structures which have been moved to one location and put back up very authentically with split shingles etc.. I have seen none that have portland cement there-I see red TN clay? FWIW, we used to go there just south of us for their fall festival and bluegrass music, crafts and old time demonstrations. If anyone want's to see a large number of old log buildings and a great Appalachian museum that's the place! Maybe they show on a website? They have a retail store open daily-covid times are a question but might get another good chinking answer there too?