Stucco is strong and relatively maintenance free, but it will crack if a building shifts. Diagonal cracks running out from the upper corners of windows or doors may telegraph big trouble. Building loads often concentrate on a header–a load-bearing member over a door or window opening–and diagonal cracks may be a sign that the header is not adequately supported. In other words, the house’s framing or foundation may be shifting.
Inside the house, look for concomitant cracks in drywall or plaster at the corners of windows or exterior doors. In older homes, diagonal cracking may also occur over interior door frames where excessive point-loading above combines with inadequate support beneath. In such cases, it’s also common for the head trim of the door to tilt down towards a failed support post or a too-small pad.
This posting is excerpted from Renovation 4th Edition, just published by Taunton Press. R4‘s 614 pages include thousands of field-tested tips and techniques, 250+ technical illustrations, roughly 1,000 photos selected from the 40,000 I have taken over the years, and lifetimes of experience that builders have shared with me. I hope you find Renovation 4th Edition useful. — Mike
© Michael Litchfield 2012
The diagonal crack running out from the upper corner of this window suggests a header that is not adequately supported and, quite likely, foundation problems. A savvy home inspector will look for corrobrating evidence elsewhere. Renovation 4th Edition
This dramatic crack through a corner of the same building was caused by a drainage system that had been clogged for decades. Instead of runoff being routed away from the house, water collected at the foundation and eventually undermined its footings. Renovation 4th Edition
Renovation 4th Edition contains the collective wisdom of hundreds of master builders and tradespeople across North America.