I have a problem
from a job that I designed about a year ago. The topping of 1.5"
lightweight concrete specified by the architect has come unstuck in some
It seems to
be near support lines that the problem occurs, which means that it is
probably because of deflections in the underlying joists on each side of
the support line. (Like cracking on a steel deck and concrete floor over
It is not just
cracking of the topping along the support lines, however. It seems
to have cracked about a metre to the side of the support line, creating a
cantileverd portion of the topping still attached to the topping on the other
side of the support line. (This would be easier to describe with a
sketch...) The cantilevered portion moves when you walk across it.
The client's not impressed.
I specified these
joists to have L/360 deflectin limits under live load, L/240 under total load,
and I am sure that this has been respected.
It would have been
nice to have specified some sort of saw-cut or tooled joint above the support
How is this treated
normally? Has anyone had a similar problem? Any comments would be
appreciated - much appreciated.