Tiny side extension for downstairs toilet. Is it possible?

Discussion in 'Building' started by Flipjango, 23 Nov 2021.

  1. Flipjango

    Flipjango

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    Our house is on the corner, with a road running along the side. We have an alleyway that is only 100cm wide down the side of the house (that measurement is right up to the boundary with the pavement). We don't need this space to access the garden as there is already a side gate at the end of the garden so mostly its just a horrible dirty abandoned space full of pigeons. I'm contemplating the possibility of building a tiny extension to put in a downstairs toilet. I have a feeling we can build right up to the boundary, though am assuming we'll need PP as its onto the road. The idea is that the wall of the toilet would replace the boundary fence for this section. So including footings and thickness of walls, is it even worth contemplating? Or will the resulting room just be too small to bother with? We only want to tiny downstairs toilet and maybe somewhere to hang coats in there so don't need it to be very big, but its the only place we can fit a downstairs toilet without having to have it go off the kitchen. Also contemplating whether we could build it as a prefab as I have a feeling this may require smaller footings?
     
    Last edited: 23 Nov 2021
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  3. cdbe

    cdbe

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    If you can get the planning then it's technically possible - you could remove the outer skin of your existing external wall to gain width. 800mm internal is a good target to aim for and will "feel" wide enough.
     
  4. Flipjango

    Flipjango

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    Think we'd have to assume we can't remove outer skin as house has solid walls.
     
  5. RandomGrinch

    RandomGrinch

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    Hi,
    If you haven't seen this thread, it might be worth a peep!
    https://www.diynot.com/diy/threads/downstairs-toilet-room-size.580187/
    From information I have seen elsewhere, there will have to be permissions for a new toilet connection and BC might have some concerns over ventilation.
    ...and it's may not be something that will recoup it's build costs when selling, but it would be very useful! :)
     
  6. Flipjango

    Flipjango

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    I don't see ventilation being an issue as there would be 3 outside walls so easy to get a fan in there and a window. Its not really about adding value.Thanks for the link, though its not quite what I'm looking for. I'm more interested in finding out what sort of space is likely to be achieved with the thickness of the outside walls under current BR, as not sure what we'd end up with.
     
  7. RandomGrinch

    RandomGrinch

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    I think that's my point from the link - an interior space of <700 - 750mm would seem a bit too tight for a loo. If you can find a construction method that will give you a wall 300mm finished width or less, you may have a chance!
     
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  9. cdbe

    cdbe

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    You can, it's just work. Not that I think anyone would, but technically you could remove the entire section of wall and put in a 75mm stud wall.


    I built my extension with a 75mm cavity and higher performance insulation and met the regs so the wall was 275mm but has to be dot and dab'd but still gained a few extra cm.

    Here's a couple of mine, the top one is 810mm wide and the bottom 780mm so I think you could go down to 700 and it'd still be acceptable.

    IMG_20211123_095645856.jpg

    IMG_20211123_100151154.jpg
     
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  10. RandomGrinch

    RandomGrinch

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    SIP panels might do it?
    And a question I'm not sure about; would insulation requirements be less stringent as a downstairs loo may not be classified as a 'habitable space'?
     
  11. Flipjango

    Flipjango

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    That's great. It can be quite a long room and I can put the door in the middle with washbasin facing the toilet, one at either end, so its just the width of the toilet and moving around that's the issue at least. Yours looks fine and has a basin in there too!
     
  12. Tigercubrider

    Tigercubrider

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    no idea of layout but it makes sense to use the entire length of the "unusable alley"
    if you have a long narrow space make two rooms, and have the loo at one end facing (maybe) a shower. Then have an entry to the second half for storage.
    I am no builder but there must be all sorts of alternative ways of building a wall alongside the boundary that allow thinner walls while keeping insulation up?
     
  13. oldbutnotdead

    oldbutnotdead

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    Might not add value on resale but a downstairs loo is a lovely thing to have- good luck with it :)
     
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