The peninsula is a favorite device of mine for making the transition from kitchen to family room. But I have always had trouble connecting the stubby end of the bar top to the top of the kneewall. I shuddered each time I saw the temporary 1×2 props sprung against the ceiling to hold down the top while the construction adhesive set up.
So on my last project, I asked the counter fabricator to bevel the inside edge of the ledger that is affixed to the underside of the bar top, as shown in the drawing. The ledger, which is beveled at 60°, locks into a complementary angle in the 1×8 subcounter. This 1×8 sits directly atop the kneewall and is affixed to it with 3-in. drywall screws. The 1/8-in. gap allowed me some room for rotating the top over the square edge of the subcounter. I thought the free play would allow some room for fine-tuning the position of the bar top, but the system worked so well that no adjustment was necessary. To hold the bar top in place, I ran 1-1/8-in. screws through the subcounter into the top.
Alan Abrams, Washington, DC