I have a single story residential home with hollow 8" CMU block walls and wood framed roof. Client wants to add wood framed 2nd floor. It is a 27' x 30' box with upper and lower walls aligning, so pretty simple job. There are existing wood framed lower level additions on 2 sides, so only the north and south CMU walls are exterior, but 2nd floor addition is only over the central CMU walls. Easiest way I have dealt with this in the past is to add wood framed shear walls inboard of the CMU to transfer shear from upper to foundation. Would also need short crawlspace shear walls to continue from lower level to existing footing, which would need to be extended inward to create room for the new shear wall sill plate. In this case, due to existing layout & no remodel happening on lower level, the addition of 5" to inside (or outside) of all walls is not feasible. I am exploring all of my options for reinforcing the CMU. Adding grout & rebar, carbon fiber, Quickties (TM), etc. However, when I look at ASCE-10 Table 12.2-1 it appears the only option that is permitted in SDC D is Special Reinf. Masonry Shear Walls. I am having a hard time determining exactly what that entails by reading Section 14.4 as referenced. I do not have copies of TMS 402, ACI 530, ASCE 5, TMS 602 or ASCE 6 as I typically do not do masonry construction except in minor residential bits like this. I am wondering if anyone can give me the bottom line of what it would take to properly retro-fit these CMU walls? This is a fairly minor residential remodel so when I first met with the client I assumed we could figure out a reasonable way to retro-fit the CMU. I also wonder if there are any exceptions that would allow a more simple retro-fit.
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