One of our specialities is historic renovation of mainly large downtown Charleston properties.  This work is not for the faint-hearted and generally involve a strip-out down to the studs and removal of every dubious improvement made over the last 50 years or so.  There are some lessons we have learned along the way that we’ll share here and in a series of upcoming blogs.

This is the first, and one of my particular pet peeves. Portland cement. Waterproof, fast setting, strong in a well designed structure, great for modern buildings.  But please, please never let this near your historic Charleston home and here are the top reasons why:

• Cement, of whatever type, will not let water through which is why it is used for swimming pools and seaport construction. 
• All homes built before the middle of the 20th century will have a poor-to-dysfunctional damp proof course if they have one at all. 
• Water will creep up the walls by capillary action to a height of about 3 or 4 feet.  It has to get out somehow.

With lime mortar construction and lime plaster, the walls will breath.  The moisture will get into the surrounding air by a process of slow evaporation in a way that it has since the home was built.  This is until someone coats the walls to floor level with cement.  Then, The moisture finds a way to get out via anywhere else leaving spalling plaster, failing mortar joints, salt deposits and a generally awful mess within a year or so.

So if you have a historic home, our plea is to repair it with materials sympathetic to its structure.  Use lime based products for plaster and mortar wherever possible.  They will move with the house and breathe with the house and soon become indistinguishable from the original structure.  In restoration work on historic Charleston real estate that’s the mark of an expert with the understanding to perform the repair correctly.

Tip – on the Gadsden House we have removed 50 year old cement patches and brick pointing where possible and replaced with a modern lime mortar mix resulting in a much more satisfactory repair.