How to deal with different floor levels between house and granny annexe

Discussion in 'Builders' Talk' started by SteveMJ, May 15, 2020.

  1. SteveMJ

    SteveMJ Active Member

    Hello folks,

    At some time in the nearish future I want to incorporate my main house with a 'granny annexe' and extend the main house's kitchen too.

    The annexe was converted and extended by the previous owners from the double garage adjoining the house.

    One aspect I am struggling with, is think how to deal with the annexe floor level being about 6" (150 mm) below the main house.

    As I see it, if the whole annexe was build up to match the house floor level the the annexe rooms would have very low ceilings. The former garage has a pitched roof, I think that would be a huge costly thing to raise. The extended part of the annexe has a flat roof, so I guess that could be replaced and raised.

    I would like to have some ideas as to how this may be dealt with before I talk to builders etc. I am thinking that the forum contributers would have come across this sort of thing before.

    Thanks for your advice and stay well. Steve
     
  2. Are you just wanting to find out how you’d build up the levels to keep them flush? If so, there are various options that comprise screed over insulation, T&G boards over insulation as a floating floor or T&G boards over joists. What’s the existing base, concrete?
     
  3. SteveMJ

    SteveMJ Active Member

    The house and annexe are concrete throughout. I don't see building up the level to be a proble; either a suspended/raised floor or loads of concrete.

    The problem, as I see it, is that the ceilings will be low with the raised floor. Two floor levels in adjacent parts of the house will make the areas feel discontinuous. Sorry, I didn't make that clear enough originally.
     
  4. Oh ok. So what’s the current floor to ceiling height, which would be reduced by 150mm once the floor has been raised?

    Any photos of what you have at present, both internally and externally?
     
  5. SteveMJ

    SteveMJ Active Member

    I'll take some 'photos and make some measurements too. Will add these here later. Thanks DOHa
     
  6. SteveMJ

    SteveMJ Active Member

    The photo show the doorway leading from kitchen to side of annexe. The difference in floor levels is 175mm. The ceiling heights are 2.4m in both the house and the annexe.



    upload_2020-5-15_19-36-57.png
     
  7. In the annexe, has the wood flooring been laid straight onto concrete?

    So by the time you raised the annexe floor, your floor to ceiling would be a little over 2.2m and you would definitely want that increased? Bear in mind a floor to ceiling height of 2.1m is what is normally achieved in a dormer loft conversion. But to increase the ceiling height, you will have no option but to raise the existing flat roof. This may also involve re-doing some of the pitched roof element.

    Both of those alterations may require Planning approval and they would require Building Regulations approval. If you’d be happy with a slightly lowered ceiling of approx. 2.2m, you’d avoid the need for any approvals.
     
  8. SteveMJ

    SteveMJ Active Member

    Thank you DOHa,


    Your question is valid, (...2.2m and you would definitely want that increased?) thank you for making me think about it differently. I can see a temporary carboard ceiling going into an area to test my reaction.


    The main house and small portion of a corridor in the annexe has Amtico throughout. This is laid onto concrete. The two large main rooms of the annexe have carpet.


    I had been toying with changing the existing flat roof section of the annexe to something like the image below. This would allow more light in and avoid a 'too boxy' appearance. A neighbour has extended without and the interior is dark IMO. Our flat roof is felted and 20+ years old, with no problems identified so far. It could be due sometime soonish. I was also thinking of adding a small terrace off the master bedroom and I would expect the roof was not designed for that purpose.


    I am currently anticipating all work would be ‘permitted development’


    Again, thanks for your time and input, stay safe. Stephen



    upload_2020-5-15_22-55-17.png
     
  9. jonathanc

    jonathanc Guest

    What is the old garage roof made off? Trusses or cut roof?

    if you want to take the ceiling up then if cut roof just rework the timbers. If trussed then look at raised tie trusses. It’s not that hard to strip off and re lay the roof
     
  10. SteveMJ

    SteveMJ Active Member

    Hello Jonathan,

    I think it is a cut roof (this is not my area of expertise) according to Wikipedia/internet ;-) IIRC I can walk (stooped) along the centre and some of the previous owner's junk is still up there.

    The way you speak this sounds like a relatively stright forward job for a builder. The only areas of reduced height would be where the former garage was itself extended and a supporting bean has been added; but then tthat could be raised and reseated too.

    Thank you, I am feeling more confident now when I talk to a builder.

    A great help, stay well :) Steve

    upload_2020-5-16_10-4-58.png
     
  11. stacyschrist

    stacyschrist New Member

    Regarding the issue with the annexe floor level, I can understand why you're struggling to come up with a solution. Building up the entire annexe to match the house floor level would definitely cause problems with the ceiling height. Raising the pitched roof could also be quite costly. Have you considered installing a ramp or small staircase to bridge the gap between the two levels? This could be a more cost-effective solution and would still allow for comfortable ceiling heights in the annexe rooms. I'm sure other contributors to the forum may have some other great ideas to share as well. Best of luck with your project, and I hope everything goes smoothly! Oh, by the way, I recently got a granny annexe built too by some fantastic contractors. Let me know if you'd like their contact information.
     
  12. Mr Rusty

    Mr Rusty Screwfix Select

    thread archaeology. I reckon it's done by now
     
  13. SteveMJ

    SteveMJ Active Member

    No not done - grandchild came along and has occupied much of my time (delightfully, I might add :) )
     

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