I recently received a call from a reader who had seen my September/October 2014 article on guardrail post kits and was trying to sort out how to attach posts to a 2x6 frame. His question was whether or not these post kits would work with 2x6 rather than 2x8 framing (the size framing used to build my test assembly), provided that similar blocking to the detail described in the article was used.
I told him that the only way to know for sure is to test the assembly, but that I saw no reason why you couldn't use 2x6s, since the key is the blocking, and the only change would be the 2-inch height differential with the rear block. At worst, the rear block would have to be doubled to provide enough space for additional screws.
East Greenwich, R.I.