Installing a new bath or shower room may seem like a simple job that reduces the floor size of one of your rooms but does not affect others in the building.  However, there are other considerations as follows: Drainage run – the general rule is that horizontal runs of drainage pipes must be of limited length.  Also, joints in horizontal pipes are more susceptible to failure than vertical pipe joints.  Where you can locate your proposed bathroom/shower room will depend on connections to existing waste pipes and how these can be reached.  Early investigations may include finding out which way the joists run within your property to see if a waste pipe can be run between the joists.  If the joists run against the pipe direction you wish to achieve then you may have to consider a raised floor for the bathroom/shower area. Waste pipe capacity -  to comply with building regulations there is a limit on the number of WC, bath, wash basin and shower connections that can be connected into standard 100mm 4” waste pipe.  Therefore before a freeholder/freehold company can grant consent calculations as to the number of people currently connecting will be a consideration. Ventilation – All waste pipes must be ventilated, usually up to roof level (at least 1m above any windows), or via an air-admittance valve (a one way valve that takes air into a sealed stack pipe.  It is the air that enables the water to be flushed/run away. Stacking principles – On new build properties many local authorities now have rules on “stacking” which simply means building bathrooms on top of bathrooms and kitchens on top of kitchens.  There are logical reasons for this as future leaks/floods cause less damage, horizontal pipe runs within dwellings become rare, noise from washing machines/WC’s flushing is less likely to cause annoyance.  We recommend you find out whether there is such a policy affecting your block. Overflow pipes -  ideally a WC overflow pipe should take water in the event of an emergency out of a bath, wash basin or WC and through an outside wall.  In certain circumstances connecting an overflow into a waste pipe can be approved but this should be at a suitable distance and height so as not to create a backflow of bad smells. Maintenance – remember bathrooms and shower rooms require regular maintenance to renew mastic seals and any water or other damage caused during the building works will be your responsibility.  Also the future maintenance of any pipework from the point it serves exclusively your demise remains your responsibility. WC’s that connect to 50mm 2” waste pipes (for example Saniflow systems) are not recommended as without extremely careful use they will be susceptible to blockages.   Back to alterations