Design of masonry window sill

[PG35]

Is the masonry below a window to be desinged as a cantilever? I notice that drawings from another consultant does not show this as reinforced. Could this be a mistake?

The situation I'm referring too is 3 feet of 8" block below a 12'-0" wide x 5'-0" high window.

If designed as a cantilever the block needs reinforcement. I don't think windows should be relied on to provide lateral support.

Can anyone comment on this?
Thanks.
PG

 

[msquared48]

Doesn't have to be a cantilever.

Will have a bond beam with reinforcing under the window anyway. If normal BB reinf is not sufficient, increase it or the BB depth to make it work.

Chances are that minimum reinforcing will work unless you are in a high wind area.

Mike McCann
McCann Engineering

 

[PG35]

I forgot to mention that the 3 feet of masonry is above a poured concrete foundation wall. There is no bond beam specified below the window. The window jambs are reinforced with 1-#5.

 

[DaveAtkins]

Depending on how wide the window is, the 1-#5 at each jamb will not be sufficient, in my experience. The wind load from half of the window will go to each jamb.

As msquared48 mentioned, there should be a bond beam right below the window which spans horizontally to the jambs.

DaveAtkins

 

[JedClampett]

Code (ACI 530-02, Section 1.13.2.2.2.1) says you need to provide horizontal reinforcing at the top and bottom of openings. It gives minimum sizes that permit the use of wire reinforcing, but most details I've seen use a #5 bar. We have this on a typical detail that we always include on CMU projects. I wouldn't be surprised if you had a similar detail.