Expert: Dan Griffin - 11/19/2008

Question
I our six months old house I have noticed several hair line horizontal cracks in different walls. The walls are reinforced concrete walls (load bearing). The cracks are approximately two feet or more long. Also in one wall two vertical cracks starting from roof till window is noticed. Should we take them seriously or they are just shrinkage cracks and not very dangerous.
Thanks

Answer
Mechanical engineers design weapon systems, etc.
Civil engineers design targets!!!!


Sama, I can't see the cracks, but if they are relatively short they sound like shrinkage type cracks.  They may indicate pressure and stress on the walls, but I don't think they indicate anything dangerous or worrisome.

I don't know how hairline these things are.  A forencsic or soild engineer will usually set up some "telltales" to monitor stress cracks.    Make a careful mark (pencil will work) to mark the wall at several monitoring points.  If it is large enough to insert something like a drill bit or feeler gauge o similar to measure and record, create a log file.  Monitor once a week (which may be way too often) or once a month at the same point to see if the gap is getting larger.  I wouldn't expect any movement until there is a major temperature or moisture change on the  outside.

I suspect the building is just settling into its new surroundings.  I also suspect or assume that the exterior is well damp proofed and has drainage to deal with water table/water intrusion issues.  If the gaps continue to grow in width or length they may require more consideration.