Expert: Bruce E. Johnson - 5/3/2010

Question
Hi,

I am building a 2 story house using concrete blocks drystacked and coated on both sides with SBC (Surface bond concrete).

My questions:
a) should I use larger size blocks for the first story, I intended on using standard 8x16x8 blocks?
b) I yes to a, then should I center the blocks of the second story in the middle of the block underneath or could I line them up to the external edge?

Best Regards,

Answer
Hi Steven, if you are using say 12" blocks on your first floor walls and 8" block on the second floor walls you should always align the block to line up on the exterior surface unless you need to offset them to accommodate some sort of veneer stone or other wall covering. Otherwise you may be subjecting yourself to water leaks.  Water running down a wall will hit the offset and try to get inside the building unless you flash it somehow.  We normally only go up to 12' high with 8" masonry unless you are using poured tie columns every twelve to twenty feet and tie beams at each level.  Most of my taller buildings use 12" masonry and fill cell construction if we are doing bond beams with only filled cells and no poured tie columns or tie beams.  I have never done a dry stacked type of masonry as you describe.  Sincerely bruce e johnson