Does a side return extension courtyard/light well have to have access via a door?

It is always preferable, and under Building Regulations, necessary to provide safe access and egress to all areas of a building that will require maintenance. As the previous poster responded, more details are required, but escape routes are also critical, and you cannot escape via a habitable room (without some engineering solutions e.g. misting system or fire curtain or alternative means of escape, which still need to be agreed with an Approved Inspector or the Building Control officer. Previously, light-wells between a building and extension were created to allow access to a drainage manhole, but now Thames Water (and other water companies) will not allow a Build-Over agreement on a Public sewer which they own and they must always have access to it. You can usually tell if your drain is Public or Private - if other houses drain into or through your manhole, than it is Public and you will not be able to build / enclose it, and must provide 24 hours 365 days / year un-manned access for the water company. It is still possible to enclose a lightwell by relocating the Public manhole, though this is far more involved, requiring a drainage survey and relocation details from a Civil engineer and a Build-Over approval from the Water company. All more complicated and more costly. Please could you provide more details to allow a more relevant response. Regards Robert A

I`d love to be able to help you here but I`m afraid you would need to provide a bt more information ie in the form of plans and elevations before anyone could get the picture here. Sorry but this might explain lack of interest and apart from that there is a concern that on providing information about something which has not been well studied could tempt an incorrect response. So to advise you I`d suggest you draw up some sketch plans with dimensions plus elevations and photographs . Pay to see a local architect , architectural technician doing this sort of work or a surveyor and seek some professional guidance.