What Happens When…the Top of a Masonry Wall is Left Open? (Case Study 1)

Posted by in Case Studies, Masonry, What happens when ...? | February 01, 2016

Ever wonder if conventional wisdom, common sense, or old wives’ (in this day and age of political correctness I probably should include old husbands’) tales are accurate?

This blog begins what I hope to be a new recurring series of case studies that begin with the thought “What happens when..?”  I plan to photograph various construction conditions that I come across to help us better understand how things work out in reality.  Here is the first.

I’ve always heard that the top of masonry walls should be covered to prevent rain from entering.  But really, how much rain water can get into the top of a masonry wall.  Apparently more than we think, as seen from these photos.

Figure MWW-1 Rain water has wet top courses of block and reinforced cores (vertical lines of wetness).

Figure MWW-1 Rain water has wet top courses of block and reinforced cores (vertical lines of wetness).

 

Figure MWW-2 Wall exhibits wetness in upper courses.

Figure MWW-2 Wall exhibits wetness in upper courses.

 

Figure MWW-3 Rain water  collects on mortar ledge extruded from the bed joints and it soaks through the wall at the bottom of the block.

Figure MWW-3 Rain water collects on mortar ledge extruded from the bed joints and it soaks through the wall at the bottom of the block.

 

In this case, the lack of covering at the top of the wall has allowed a significant amount of water inside the wall.  Now I wonder, “Will that cause efflorescence at the top of the wall?”  We will just have to watch and see.

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