Do I need planning permission to build over a shared manhole?
I want to cover the manhole to add an extension to the flat at the side of my house
Generally, well fitted-drainage channels operate without any need for regular servicing and manhole covers are typically not lifted on a frequent basis. Photograph: Getty Images
I have a small flat at the side of my house and when it was built the manhole (serving four houses) was not covered over. This leaves a very small space outside but it cuts into the living room giving it an odd shape. I have been advised by an architect that the manhole can be built over by a competent builder. Is this correct and do I need planning permission?
Space is generally at a premium in an urban setting and for this reason one seeks to maximise the benefit when constructing an extension.
I note from your query that the manhole was left in the open space when the flat was originally constructed at the side of your dwelling.
Generally, well fitted-drainage channels operate without any need for regular servicing and manhole covers are typically not lifted on a frequent basis. However, in instances where drainage pipes are damaged or blocked then it will be very necessary to have a fully accessible manhole available locally. The purpose of a manhole on a drainage run is to allow for the inspection of drainage channels and also to allow for the cleaning of drainage pipes when they become blocked (a specialist contractor is typically engaged).
I note from your query that this manhole is positioned on a drainage channel which serves four neighbouring houses and it is therefore most important that the drainage channel is maintained free-flowing and that there is easy access to the pipes if required.
To answer your specific query, it is recommended that one does not construct an extension over the manhole and it should be left, where possible, in an outdoor environment. The previous builder decided not to build over this manhole and, in the absence of a site survey, I would consider that he was correct in what he did.
If you decide to proceed with building over the manhole, then you will need to incorporate an inspection manhole within the extension, which is not ideal. In the event of a blockage in the drainage channel then any inspection/maintenance work will only be possible internally within the flat.
Irish Water is the relevant statutory authority for mains-connected waste water drainage channels. I expect your own connection accesses their network. In such cases, it is important that you contact Irish Water directly as it will be important that you adhere to appropriate standards for any proposed work.
Andrew O’Gorman is a Chartered Building Surveyor and member of the Society of Chartered Surveyors Ireland, scsi.ie