I'm refurbing my downstairs toilet/shower room and connecting to an unvented stub stack. In the new layout the shower will sit between the toilet and the stack. Is it OK to connect the shower waste using a very short 40mm pipe run direct into the horizontal(ish)110mm waste that runs from the toilet using a strap boss. I would like to do this instead of using a boss on the stack as this would give me a *much* shorter and less convoluted pipe run for the shower waste, with no need to avoid joists etc. Based on past experience I am paranoid about shower/bath waste blockages, and once the shower tray and floor tiling is down it's not coming up again in my lifetime. Thanks in advance for any advice.