Do I need permission to move a shared drain in my back garden?
Property Clinic: Your questions answered
Drain. File photo. Photograph: iStock
I want to build an extension to the rear of my property. There is a drain in the middle of my back garden with waste coming from my house and the neighbour’s house into the drain. If building an extension, it is almost certain that the drain will have to be relocated. I have three questions: Will we need planning permission? Will we need permission from our neighbour for the work? Will the cost to relocate drains increase our overall costs massively?
The design of your proposed extension will need to be reviewed to ascertain that it meets relevant planning requirements (eg, is it an exempted development or a does it need a formal planning application?). You can consult with your local planning authority (county/city council). The actual mapping details of water/wastewater pipes at your property should also be available through the local authority (on behalf Irish Water). The IW National Geographical Information System contains the most up-to-date information.
The local authority will generally allow construction over public drains but specific requirements will apply. The extension will have to be designed and constructed so it does not (or will not) cause damage to the drain. Special structural foundations might be required. I would recommend that you incorporate accessible manholes either side of the extension to permit access to service the drain for future maintenance and rodding.
However, if the drain is currently in poor condition, it is advisable that you consider replacing it during the construction of your extension to prevent possible future problems. If it is feasible you could relocate the drain. However, you should consult with the local authority in advance as it will have specific requirements for drain relocation and reconstruction. Permission may also be required.
You do not need to consult with your neighbours if you are relocating a sewer which is on your own property. However, it is always advisable to consult with neighbours to inform them of your intentions, as the use of the sewer may have to be temporarily closed off during the works.
The financial cost of the works will depend on a number of factors: the size of the drain, its length and depth, confinement of the site, etc. I would recommend that you engage the services of a suitably qualified professional (eg building surveyor, engineer etc) to specify and oversee these works.
You will also need to engage a reputable and experienced grounds work contractor to carry out the works. The contractor should be approved by the local authority and provide all necessary insurances. A full specification (drawings and specifications) should be submitted to the council in advance for approval prior to undertaking the works.
Andrew O’Gorman is a chartered building surveyor and member of the Society of Chartered Surveyors Ireland, scsi.ie