Expert: Dan Griffin - 3/18/2009

Question
QUESTION: I have a warehouse made of cinder block which has glass block windows in it.  The windows are starting to leak and need to be replaced.  The window openings are roughly 5'x5' and have a lintel above them.  My question is since these are load bearing walls and the lintels also need to be replaced do  need to support openings or should the wall be able to hold itself until new lintel will be installed?  If support is needed what do you recommend?

ANSWER: Ken, are the existing lintels made of steel?  Usually CMU buildings use trough or hairpin blocks that are slushed with steel and concrete.  If they are slushed block lintels I can't imagine needing to replace, for that matter, I can't imagine a steel lintel so far gone that it would need to replace.  Has there been some type of failure?  Some CMU buldings use precast concrete lintels - again, it would seem strange to need to replace.

You don't tell me how much masonry and load are above the windows.  Masonry bridges in 45 degree angles.  Masonry usually has filled trough block beams cast every 4 feet vertical and horizontal in additon to any window/door lintels.  There is certainly some risk, but I would be fairly comfortable breaking out what you need to accomplish the task at hand if there are several feet of masonry above the lintel or a varified trough block.

If I've not understood the issues, holler back.

---------- FOLLOW-UP ----------

QUESTION: It is a precast block/concrete lintel(it's painted so it's hard to tell).  It is cracked through and is beginning to sag in the middle.  Above the lintel is 6+ feet of block.

Answer
Ken, is the structure tight to the lintel meaning that it is sagging also, or is the lintel failing on its own?  If the structure is sagging, is there a particular load concentrated above?  Steel bar joists?  If so, are the bearing ends on this window wall?  Are there any other cracks or signs of failure in the area of this failing lintel?

It will be difficult to grout fill hairpin or trough blocks (it is possible) so the best solution might be to find a precast lintel.  It might also be effective to consider eliminating the window and blocking the hole shut.

A good mason will adise you on the best approach that will work with the men and equipment he has available.