Expert: Dan Griffin - 8/20/2008

Question
We want to add two windows and a door to a building we are renovating.  The outside is brick and the inside is cement block.  One window opening is approx 64 inches wide.  The door and other window is approx 48 inches wide.

The top of the door opening will be cut into cement block and the 2 windows will be cut into the mortar between the block.

The cement block is not staggered.  It seems to me that there would be a good possibility of collapse.

Answer
Bary, you will need to create a lintel for each opening.  I don't have my book handy, but the 48 hole will work with a 3x3x1/4 steeel lintel that is bearing at least 3 inches on each side of the opening, the bigger opening may require a heavier angle.  Bothe the block and the brick will need a lintel.  Another method common in cement block would be to make the opening taller than required and lay trough blocks filled with steel and concrete and relaying the block above.  The holes will probably hold during the work if there is at least 3 foot of CMU above the hole as it bridges at a 45 degree angle.  It is possible to isntall the lintels "backwards", but they will show on each side of the opening.  They should be through bolted or welded to keep them in location.  Again, they will need to bear on each side of the opening, and it would be best to slush the cells on each side of the opening.