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Old Walls – are they always built well?

We recently got an email from Paul G. who was working on rebuilding and old wall around a church that probably dates to the mid 1800’s. There were lots and lots of traced stones such as the one pictured below.  Paul Asked if it is common for old walls to have been built using poor techniques?  The answer seems to be ‘yes’.  Many old walls were built with what we would call poor techniques (so are many new walls too).

This can be due to all kinds of factors, here are a few common ones (note how they also affect modern walls a well):

  • Lack of knowledge about building with dry stone
  • Stone that does not lend itself to the desired dimensions or aesthetic of the wall
  • Lack of tools to be able to shape stone
  • Limited resources (labor/budget/material)

In many cases it is fascinating to see how long rather poorly built walls can in fact stay up.   In other cases an old wall was actually previously rebuilt some years ago, thus perhaps the original wall was fairly well laid, but when rebuilt it was improperly done, resulting in a relatively quick demise.

Historical land use patterns also play into how walls were built.  Many walls in New England were hastily built with the idea that they would be rebuilt later.  But with the invention of barbed wire, and people moving off the farm, most never were.  Some walls were originally built as a single stack wall, and then as more stones were brought out of the field and 2nd face was built.  Making for a structure which generally lacked through stones and often had a lot of large stones ‘traced’.  With a keen eye a lot can be inferred from the placement of stone in historic walls.

In most cases walls were built reasonably well given the limitations at the time of building.  However it is not always clear what those were.  We can also often surmise that the walls that are little more than a linear pile of stone were built less well than those that still bear a semblance of an upright wall.  When dissembling and old wall, it is always interesting to see if you can determine what caused it to fall.  Tree roots, tilted foundations, and impacts from farm equipment are often identifiable.

Throughout history, when a wall would fall down, it was general practice to rebuild it better.  Thus comes the question pertaining to historic preservation and restoration of what to do when rebuilding an old wall.  This topic could easily be an entire book, but in essence, one option is to rebuild the wall better than it was before.  This could change the visual character of the wall but is in keeping with what has been done throughout history.  A second option is to try to rebuild the wall as it was at a certain point in history, recognizing it will not be as strong.  It is a continuum or range between the two, and is not necessarily one extreme or the other.

My personal preference, when there are not other outstanding factors, is to rebuild the wall so it is structurally much better.  I find a strong wall looks good, even if different from before.  I like to think that long in the future when some of my walls fall down, if someone finds a better way to stack them they would do that, and not compromise the strength simply to replicate something that failed.

 

The image to the left shows the wall Paul was rebuilding.  He writes that this is certainly not the worst example (that one was 18″ long and only 3″ into the wall.

While the large stone in the picture is traced (set with the long side out along the face of the wall), in this case it may not be so bad given that it does still extend in to the center of the wall.  We could not know more without seeing all aspects of the stone and what it was surrounding it.  Generally tracing is to be avoided.  However if the stone extends at least 1/3 to 1/2 of the way into the wall it is often acceptable.

Whenever you think about possibly tracing a stone (even if it does go reasonably well into the wall), I recommend first asking yourself:

  1. Could it be better used in another part of the wall (foundation, through, cheek end, cope, cover, etc)
  2. Does the shape only lend itself to being used in this way
  3. Would it be difficult to shape into something that would not be traced
  4. When used traced does it create additional weaknesses (sitting on 3 or more face stones below, causing running joints, etc)

Sometimes setting a stone in a way that is technically traced is the strongest way to use the stone, but that has to be carefully determined.  When in doubt, just don’t trace stones.

-Brian Post
Executive Director of The Stone Trust
DSWA-GB Master Craftsman & Examiner
Licensed Landscape Architect – Vermont