Increase in height of existing brick/block wall

[knfeng]

I'm looking at a residential addition project that consists of adding a second floor on and existing single story house. The existing exterior is 4" brick/ 4" block composite walls that are approximately 7'-0" tall above finished floor, with 8" cmu basement walls below. The proposed addition above has a ceiling height of 9'-6" which requires somehow increasing the height of the existing walls. The architect has initially decided to simply build a short stud wall above Which essentially would create a hinge in the wall and is not acceptable. My thought is to increase the height of the wall by continuing with the same construction (4" brick/ 4" block) since the overall finished height would meet the height/thickness limitations in the code. My concern is in the bond of the new masonry above the existing masonry and whether it will be adequate so that the existing 7' wall will behave as a 9'-6" wall. Any thoughts would be appreciated.

 

[rholder98]

The two wall sections have to be able to transfer moment across the joint--otherwise, you've still got the "hinge" you referred to. I have seen engineers cut or drill new reinforcement into the existing masonry, which allows you to continue the construction as you describe. You just have to be able to transfer your forces through the joint, much like a construction joint.