The toilet in my downstairs bathroom has the soil pipe coming up through the concrete floor. I would like to change this to a hole in the wall version and my initial idea was to just cut the soil pipe outside (Clay) and join to plastic pipe and take through the outside wall. However because the inspection chamber is only 600mm from house the pipe is surrounded by concrete make joining to it impossible. If I were to remove the old pipe can I cement in the plastic soil pipe directly into inspection chamber and do I need any special fittings. Its a brick type chamber with the pipe cemented in place?