Building over Inspection Covers
If your home was built after 1939 it probably has a private sewer system, i.e. one not owned by your local Water Authority. If you are unsure whether your sewer system is private or public you should ask your Water Authority.
If your new conservatory is planned to be constructed within three meters of a public sewer it is a legal requirement that you contact your local water authority to consult with them and get their approval before commencing.
If the conservatory is being built over an inspection cover then a sealed, screw down cover is required to prevent odours and gases escaping into the conservatory. If there are no other inspection covers close by it is sensible to move the inspection cover outside the conservatory so that you have good access to potential blocked drains. Doing this will also give you more freedom over the type of conservatory flooring you can use, as it will not be necessary to install it with access to the inspection cover in mind.
Building Over Sewers
If there is an inspection cover on the site of your conservatory, you must also bear in mind how the foundations for the conservatory will accommodate sewer pipes. You need to ensure that the weight of the foundation is not imposed on the pipe whether this is beneath the foundation or running through it.