Did you know that large diameter logs can shrink in your walls? 

When you place a dry log in a cordwood wall that is over 12 inches in diameter, there is a good chance it will shrink, even if dried to 12% moisture content.  If it receives a good deal of sun during the day, it may shrink even more. I have seen some 18-inch logs shrink as much as 2 inches

You do not need to split every 12″ or larger log end, but the ones you will put on the south side of the house will benefit from being exploded.

Many people like the look large logs in their wall.   If you are going to use larger logs it is best to place them in the middle to the top of the wall.  That way the sun won’t help them dry even more.

The best way to deal with large diameter logs for a cordwood home is to split them.  This takes care of the shrinkage problem and also eliminates the large primary check.

But, what if you want those large logs in the wall?  You can always “explode” the log and put it back together with a one-inch mortar joint.

Here are the nuts and bolts:

  1. Split the log into at least 2 pieces, but 3 or 4 also works fine.
  2. Keep those pieces together so you can find them when the time comes for wall-building.
  3. When it comes time to mortar them into a wall, simply wet the edge of the surface that will receive the mortar and put one piece in first.
  4. Mortaring around that piece (1″ mortar joint) and then do the other two or three pieces.
  5. The finished product looks similar to the whole log.


Logs this size 16″ and up will shrink nearly an inch in diameter after a heating season.

Look carefully at the faces of these logs.  Notice all the fine cracking lines.  This is the way very dry wood appears.

Note the very large log split into 5 pieces on the top right.

From left to right:  a fish, a split in half log and a star.

Stuffing a primary check with white fiberglass (which matches the mortar color) will stop air infiltration if the check goes all the way through to the outside.

Another way to handle potential shrinkage in a cordwood wall is to split ALL the pieces into unique and interesting shapes.  Here is an example in British Columbia. The wood is Western Red Cedar.

A very informative and engaging Facebook Cordwood Group page will answer your questions about cordwood.  Click on the link and (if you’d like, please join our conversation.  https://www.facebook.com/groups/cordwoodconstruction

Should you wish to learn how to build a cordwood cottage, cabin or home, please visit www.cordwoodconstruction.org   While you are there, click on the pictures, read the brief articles, check out the latest workshops and newsletter and if you are interested click on the Online Bookstore to see all the cordwood literature available in print and ebook format.Cordwood Construction Best Practices Front_Cover_-_CC_Best_Practices small pixels If you have questions that aren’t answered on the website you can email me at richardflatau@gmail.com  

Readers have requested a brief bio, so here goes:

Richard & Becky Flatau built their mortgage-free cordwood home in 1979 in Merrill, Wisconsin. Since then, they have written books, conducted workshops, facilitated  2005, 2011 & 2015 Cordwood Conferences and provided consultation for cordwood builders.  Cordwood Construction: Best Practices DVD (2018),  Cordwood Construction Best Practices 2020 (print & ebook) and Cordwood Conference Papers 2015 are the newest publications available from their online cordwood bookstore.   www.cordwoodconstruction.org

The Cordwood Workshop DVD is like taking a workshop in your home.

For more information on Cordwood Construction, click on the picture or visit www.cordwoodconstruction.org