Mark just sent me an email asking about chinking, insulation, boric acid and preservatives for a log barn project he is working on.
Mark writes:
i have an old log open barn the logs are from 1-5 inches apart it is 18 by 20 by 10 feet high i would like your chinking recipe and your insulation idea and the purpose of using boric acid also what is a good sealer to use on the chink and logs to seal it after you are done
Hello Mark and thanks for the question!
I’m going to stick my neck out and assume that the logs on the barn are hand hewn. With that in mind you may want to check out the section on Hand Hewn Chinking for starters.
Chinking for hand hewn log homes, barns and of the like is not much different than chinking log homes and cabins that have round logs. There are a couple of articles on chinking that may interest you. Take a look at what the beautiful work that the Ryans did on their hand hewn home.
Here is a link on the chinking recipe.
Through that link you will find a chinking recipe.
In addition, for insulating the space between the logs you may want to take a look at Chinking and Insualting Logs. A letter from Brian asked a similar question on chinking hand hewn log homes.
Take a look at the different methods of filling the gaps between the logs on the above links. You cannot file the entire space with chinking for obvious reasons. You can however fill a portion of the area with scrap wood — much like the Ryans did. That is actually a common way of filling the void and very typical of historic log homes.
If you would rather actual insulation between the logs you can use fiberglass insulation stuffed loosely centered between the logs but you will also need to provide some sort of backing for the chinking. I’ll Point to the Ryans again as they used a wire mesh.
Secure the wire mesh be staple of nail. The wire mesh will provide a surface to which the chinking can grab. Choose a mesh that is rather heavy gauge. For smaller voids or spaces you may not need the mesh.
As you saw in some of the articles, stone were commonly used to fill the space as well.
Since the chinking on your barn will not be structural you can also take a look at the chinking recipe for white chinking. Adding color to tone it down is simple as using organic material to using pigments or minerals.
As far as using the Boric acid. Boric acid is an excellent insecticide by itself. Dusting between the logs with powdered boric acid as you insulate is something that you should do. When insects travel through the boric acid they get the little crystals them coating them with the powder. The powder immediately begins to suck all of the moisture out of the little critter. In short time they will dry up.
By dusting the insulation and the void between the logs with boric acid you create a barrier.
Boric acid will also dry up mold and mildew.
Sealing you logs afterwards is a good idea. I personally like the Weatherall products — It is a waterbased stain and seal in one — and comes in various transparent stain colors from natural to very dark brown. Some people however swear by oil based stains and seals. I’ll have to write and article on the pros and cons of water based and oil based stains and seals.
There are very good products in both categories.
I hope that this provides you with the information you are seeking!
Thanks for visiting the site and feel free to email anytime. I would love to see photos of your log barn if you have any. And please keep us posted on your progress!
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Great info at a critical time. I’ve relocated an 1820 hewn log house.Logs have been replaced, stacked, blocked, jambed,sprung and winched (to straighten),roof structured, and had 1200 sq. ft. added to it.This house is lucky to be recieving 2 limestone, limeputty, double fireplace chimneys. 20,000 tons of the 160,000 tons of stone is original. Much of the rest of the stone has come from historical structures which which will soon be forgotten.Most of the surface coverings in the extensions are reused materials, ranging from barn siding to paint layered t&g. I could bore you with details that are to numerous to list but what I’m trying to say is I want to make sure I get everything right. With masons ,painters, owners,passer bys,and self proclaimed experts, etc……..I feel my direction requires reinforcement. All along my repeat performance has been to use rigid insulation wire mesh,stapled, and lime mortar with poslin and the same sand from the stone work. The shrinkage is minimal but not flawless. I intend to do this before I final seal. I’ve used sikens and weathershield. Neither have done what I had hoped. Anual monitering and maintenence seems inevitable.