A Common Mistake In Repair

by Don Friedman on December 20, 2016

There’s that view out the window again. (I’ve had the same view for seven years and I’m reveling in looking at something else.) The white strips of brick directly over some of the windows are a common form of facade repair: damaged steel lintels have been replaced, which requires that the brick above the lintels (which are almost certainly angles) be removed and replaced. Standard practice is to match new brick to the clean color of the masonry – and we’ve already established that this facade is quite dirty – hence the white strips.

The building in question was built in 1931, so it almost certainly has solid masonry curtain walls supported on its steel frame. The masonry may be all brick or some combination of brick veneer with terra-cotta back-up. The standard detail for window lintels in buildings of that era was that the steel angles were laid up in the brick and the next course of brick was simply laid on top, with no mortar or anything else between the lintel and the brick above. Solid walls like this prevent water entry through mass: by the time water can seep through the wall, the rain outside has ended and the inward push of vapor pressure has ended or reversed.

Here’s a blow-up of the repairs:

These actually appear to be two different campaigns of repair, or maybe two very different details used in one campaign. The best evidence that these repairs are from different times is that the most rat color is different, either because of aging (AKA dirt build-up) or because of different mortar mixes. The difference in color is pretty consistent across the facade between the repairs that look like the ones on the right and those that look like the ones on the left.

On the right, only the minimum amount of brick has been removed, and its been replaced apparently as it originally was. On the left, a much larger area of removal* and a mistake. Those dark vertical rectangles just above the lintel are weeps. They’re plastic inserts in the head joints that are meant in a cavity-wall system to allow water to leave the cavity. But there is no cavity here. There is literally nothing to weep out of the joint because solid walls don’t build up free-flowing water in the way that cavity wall do. On the other hand, the weeps do provide a short-cut for rain water to get into the middle of the wall without having to seep through the pores in the brick and mortar.

In other words, using a detail that is inappropriate for the system does no good and may do harm. But I see meaningless weeps installed in repairs to solid walls all over the place.

* It’s possible that the larger area of replacement is related to someone looking for or repairing rust on the beams that are nearby, but it’s unlikely. If that were the case, I’d expect to see some removals that were not vertically in line with the windows, and there are none.

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