Expert: Bruce E. Johnson - 2/19/2009

Question
I want to put an air conditioner in my garage wall. The wall contains no rebar; just blocks and mortar. No wiring, no nothing.

The air conditioner will be about two feet wide and maybe 18 inches high, and although I'm not sure, I will probably want to put it about seven feet from the floor, so it would have three or four courses of blocks above it. This is a one-story garage with nothing above it except a roof.

I think I can cut the hole. I have a circular saw, an air chisel, a rotary hammer, and an angle grinder. But what do I do to finish the hole? Do I have to support the top? Is there a premade metal support I can put in there, or do I have to make a concrete lintel from scratch?

Split systems and portables won't do it. It has to be a wall unit.

Thanks.

Answer
Hi Steve, you should be able to cut this hole without any added supports.  Try to make your cuts to correspond with the horizontal and vertical mortar joints.  From the top down make your measurement from a solid horizontal joint. In other words start at a horizontal mortar joint and measure down the 18". For the width if you go from one vertical joint to another then the intermediate blocks will be cut at a web.  Use the saw as much as possible.  Jackhammering will have a tendency to dislodge blocks and this is not what you want to do. As far as trimming out the opening you can take wood and picture frame the opening inside and outside and then caulk it good to keep the moisture out.   I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com