Shortly after graduating college, I had the opportunity to work for a firm specializing in architectural restoration. More specifically, inspecting building facades and developing repair programs for deteriorated conditions. As a desperate intern looking for employment, I cautiously answered "not really" to my future boss's inquiry of my fear of heights. Shortly thereafter, I found myself precariously dangling from buildings nervously tapping on limestone, brick, and terracotta facades with an inspection hammer.
Masonry construction is incredibly durable which makes it a desirable building product. There are a multitude of different types of masonry products, from clay bricks formed and fired, to highly polished marble and other cut stones, or even cast stone such as terracotta. The process of extracting masonry materials from the ground and preparing them for construction hasn't changed much in the last century. How we use them in construction has changed dramatically.
High rise construction was changed forever by the development of the elevator, more specifically the braking mechanism invented by Elisha Graves Otis which helped in preventing people from free falling to their deaths (read more about that HERE) during elevator failures. This invention made taller buildings much more feasible to the everyday users. When buildings start to get taller the walls at the base subsequently get wider to carry the loads from the taller walls. At a certain building height, the walls at the first floor become so thick to support the loads from above, that usable space and other constructability issues prevent the building from getting any taller.
The Monadnock building in Chicago pushed the building height limits of masonry load-bearing walls at 16 stories. At this height, the masonry walls were several feet thick.
Because of this problem, Architects and Engineers developed different methods of framing to support these vertical wall loads using materials like steel and formed concrete frames.
It is completely feasible, and desirable as of late, to construct buildings purely out of steel and glass without the need for masonry building products. Many consumers and building owners, specifically residential applications, demand the use of more natural materials. As such, we have begun to design buildings using masonry as a facade, a non-load bearing application, like tile on your bathroom wall. This was driven as the cost of these natural building products increased simultaneously with the use of alternative framing methods.
So what does all of this have to do with the maintenance of masonry?
It is more important than ever now to address distressed and deteriorated masonry in exterior wall applications. Since the exterior walls are only clad in masonry, the materials used are only approximately 4" thick. As such, cracks represent a true hazard to building users as well as provide areas for water infiltration, the primary cause of deterioration. Additionally, corrosion caused by water on the steel facade supports and clips contribute to further deterioration. Steel expands as it rusts, and as such, will shift facade materials around during corrosion.
As masonry building facades begin to deteriorate, the rate at which the deterioration grows is exponential. More water enters the wall construction from cracks, openings, gaps, and spalls and as this water freezes and corrodes the steel supporting structure, the facade experience more distress.
So what can masonry building owners do to prevent costly repairs?
First, be on the look out for conditions that are abnormal. Cracking is a good indication that the facade is shifting or that pressure is being applied without accommodation from expansion joints and other designed control mechanisms. If your brick is turning white, or has a buildup of mineral deposits on the exterior side, typically this efflorescence is indicative of water trapped behind your facade. Lastly, be sure to have mortar joints maintained at appropriate intervals to prevent water infiltration. Tuck-pointing, or grinding old mortar out of the joints and packing new mortar in, is a costly process, but much cheaper than rebuilding the facade.
Masonry buildings need maintenance, and by providing it, masonry construction is one of the most durable and long lasting exterior building products available.