Pitching versus Patching: story of a bad repair

Much like the English quartet, even Stone Roses age.  Especially those made of sandstone on the exterior of a building.  Common in historic structures, sandstone is both easy to quarry and carve, which made it an extremely popular building material in the 19th century.  However, it is also quite fragile and weathers poorly.


A note on sandstone as a building material- Sandstone is a sedimentary rock, which means it forms in layers, called bedding planes.  Quick and hilarious geology lesson here.   When using sandstone as a building material, it is important that it be installed correctly.  Natural weathering is exacerbated if the stone was installed incorrectly or if there is improper water entry or drainage in the building, which can cause failure.   Imagine the stone as a book.  If you lay the book facedown and place another book on top of it, it is a fairly stable material.  But if you place the book on its binding, well, you are placing a lot of pressure on those individual layers, as well as exposing them to the ravaging effects of water.  In the presence of salt, as is the case along the eastern sea board, chemical reactions add to deterioration.  The National Park Service has a great write up on stone and masonry deterioration, if you are curious.

Which brings us to our brownstone home pictured here.  Brownstone is so named for the reddish brown hue from the iron oxide found in the stone.  Found in generous supply in the New England area, it is extremely common in large cities, especially in row homes just like this.  This home is, sadly, an example of a bad repair.  The stair case on the front of this row home has been plastered.  It looks a bit like a child’s sandcastle which a wave has already washed over.  When stepping back from the building, you can see sections where the plaster patch is failing again.


Three crimes were committed here.  First, the source of the deterioration was obviously not addressed.  The stone is obviously eroding in the presence of water, but whatever the source is was not identified and corrected.  Second, the damaged stone was not properly removed before the plaster was applied.  Even had the water issue been dealt with, the damaged stone beneath the patch would eventually fail.  Third, the repair work done was poor craftsmanship indeed.  Walking around the block, I found this treatment on multiple homes.  Someone did a much better job of pitching than patching.

A warning to owners of historic buildings- make sure the treatment isn’t worse than the disease.  A bad treatment both further deteriorates a building and makes future repairs more difficult.  There are tips for picking a good contractor.  Your building will thank you.