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Building Regs: How close is 'close to a drain'?

An existing detached house has a manhole at the rear corner. A proposed single-storey extension will be stepped back about 300-400mm from the rear corner in order to miss the manhole by a similar amount.

The extension will be within Permitted Development, and hopefully the Regs can be dealt with via a Building Notice. *However*,Planning Portal states:

''You can apply for Building Regulations approval from your local authority Building Control Service by giving a building notice.

Plans are not required with this process so it’s quicker and less detailed than the full plans application. It is designed to enable some types of building work to get under way quickly; although it is perhaps best suited to small work.

There are also specific exclusions in the regulations as to when building notices cannot be used. These are:

For building work which is subject to section 1 of the Fire Precautions Act 1971
Part II of the Fire Precautions (Workplace) Regulations 1997
**For work which will be built close to or over the top of rain water and foul drains shown on the 'map of sewers'**
Where a new building will front onto a private street''

**My emphasis.

The manhole in question is the rearmost on a combined RW and foul drain, and receives only sink and washing machine water at present, but would receive foul too, from a proposed WC in the extension.

Is 300 - 400mm away from the manhole close enough to mean we have to do a full plans app?

Any experiences or thoughts?




  • You will need plans for building regs even if it on a building notice, these will flag any drainage issues so why not dos proper regs application?

    I cannot see planning issues.
  • Tony, I generally get by with very basic dwgs on a BN, and lots of agreement on site. I want to stick to that degree of simplicity if I can.

    Re planning, it appears to be unequivocally PD, so should be OK there.


  • So does the manhole feature on the water authority sewer plan, or is it a private drain? If the former you may need to apply for a build over agreement. If the latter, just carry on and do the work.
  • edited January 2015
    Good Q, PaulJ.

    Don't know. fair chance it is private. Does one find the Water Authority's sewer plan on their web-site?

    Edit: found it. They want £36 without a site visit, or £84 with one.
  • jon
    edited January 2015
    Is 300 - 400mm away from the manhole close enough to mean we have to do a full plans app?
    Any experiences or thoughts?

    Yes.. 500mm from edge of new to edge of existing. Can't remember how I know this. May apply only to drain run itself so you may be OK. You should be able to download the rules relevant to the water authority if you search hard enough.
  • The problems will also depend upon how deep the drain is, if the foundations go below the drain (or even at the same level) you can show no load on the drain = much less problem
  • I assumed footings (Walter Segal pads) would definitely be below the drain invert level. There is quite a lot of bedrock around, so it will be interesting to see what we find!
  • Every extension and conversion I have overseen has been done via Building Notice. There is no Statutory requirement for any drawings whatsover - though in practice its often good to keep on the good side of the Inspector if they request detail - bottom line is though all you have to do is communicate the detail - drawings or otherwise is up to you.

    My Local Authority has a webpage explaining avantages and disadvantages of builfing notice v full plan - I assume they all do.

    Regarding the drainage I have just come across this very issue. I no longer used Building Control only an Approved Inspector and he told me just Friday that the law changed last year (July I think) and states that if you intend to build within 3m of a public sewer you must serve a notice to your Utility Company so that they can charge you for the privilege of them coming out and telling you what to do. The flip side to this is that said Utility company is also responsible for the maintenance of the Public Sewer (even if its on your Client's land)
  • Can be done on line - My local utility company

    and what my LA says about Building Notices
  • I notice you cited...

    "Part II of the Fire Precautions (Workplace) Regulations 1997"

    I'm not familiar with those but I note the word "workplace" in the title. Does it only apply to workplaces or dwellings as well?
  • edited January 2015
    Colin, it was just part of the list I lifted from Planning Portal. Workplaces only, I think, and therefore not relevant here.

    *However* I was looking at the guidance notes on the back of a Building Notice (for a completely different reason), and it says:

    ''6. This form cannot be used where the works will involve building over or within 3.0m of a sewer as shown on the map of sewers held by the sewerage undertaker. Please make a full plans application.''

    Overkill, in my view, but pretty unequivocal.
  • Hi nick,

    Where abouts are you? If it's Thames Water, I have a 'contact' that gets me the sewer plans.. Is it not possible to move the drain and run the extension flush? Got to be the most preferable choice? Install a new access chamber outside the building with ridding access as necessary for any new bends required...
  • If this pipe run only serves the building you are extending, it is almost def not a public sewer, If it serves other props, it may well be.
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