What is minimum height above a toilet seat for understairs WC

Hi mate For new builds it is required that at least 50percent of the useable room height is a least 2.1 meters and you will need to be aware of some councils requirements for accessibility, door widths wheelchair access etc. You must remember that for a toilet to be useable one must be able to comfortably stand in front of it. The average toilet cistern height stands at 800 mm and its length is 650mm down to 600mm for a space saver. Do a basic piece of trigonometry a being cistern height b being toilet length and c being the slope of the ceiling and unless the pitch of your ceiling is hideously narrow then you will find simply that by boxing in to the 800mm cistern height and placing 600-650mm toilet in that position there is naturally enough ergonomic space for a standing human. Around one point five meters usually. In a refurbishment situation Provided the building inspector can see that you have been as sensible as possible within the constraints of your refurbishment he/she will be happy.

Hi, I’m not aware of any building regs for installing a second loo under the stairs. It would be more if it’s feasible for you and yours. You could fit a loo in your dining room if wanted.