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Help with levelling garage floor

Discussion in 'Building' started by Garryboy11, 6 Jun 2021.

  1. Garryboy11

    Garryboy11

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    I’ve posted a couple of times about my detached single skin garage conversion (to insulated workshop - not habitable - no BC).

    Roof is underway and I’m starting to plan out the floor. (Pics below)

    as with all garages - the floor slopes away from the back to the front - but by quite a bit. 0-140mm!

    The other complication is the pedestrian door height is pretty low (189 from concrete floor to top of concrete lintel) - so i need to start levelling from here at say 25mm.

    my current plan is to buy / trim / shim joists to the correct depth - increasing as the slope increases (e.g 50mm, 70mm, 95mm, 120mm etc) and lay them on bed of mortar.

    That way I can make adjustments to they are level and not worry about the existing floor level.
    I will also attach them to either a ledger board or directly to the external wall.

    does this sound sensible - any other methods I should consider?

    (sorry for long post)

    upload_2021-6-6_22-13-27.jpeg
    upload_2021-6-6_22-14-8.jpeg
     
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  3. motorbiking

    motorbiking

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    I'm wondering if it would be easer to re-lay it. You can insulate the floor and install a DPM at the same time.
     
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  4. Garryboy11

    Garryboy11

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    Hey, thanks for the reply.

    I did have a think about relaying it (putting down DPM, varying thicknesses of Insulation to match the slope - leaving at least 50mm to level, then pouring new screed/concrete on top to bring it level.

    I guess my only concern (other than my ability to do it!) was if we sell the house in the future, it maybe makes it harder to turn back into a garage if that's what buyer(s) wanted.

    Will have another think about doing it this way - thanks again.
     
  5. pilsbury

    pilsbury

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    I’d be thinking about digging up as suggested. If it’s just going to be a workshop I’d not bother with insulation. Just a DPM and new level concrete.

    I’m not sure there is a requirement for a certain slope on a garage floor.
     
  6. Garryboy11

    Garryboy11

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    Cheers. It’s less about losing the slope for a garage and more that there would be a c150mm step ‘up’ into the garage from the front outside ground level to inside the garage - so couldn’t drive a car in (again for future buyers - I won’t ever be using it as a garage).
     
  7. pilsbury

    pilsbury

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    But if you were digging it out, you could relay it at a lower level. Say a 1 inch step up to save water ingress. No need to relay to the highest point.
     
  8. Garryboy11

    Garryboy11

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    ah! Lightbulb moment. Got it. Sorry was being a bit dense!

    Ok. Will def give this some thought.

    thanks all
     
  9. Tigercubrider

    Tigercubrider

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    What does the ground do at the garage end outside?
    You could dig a pit at the end to see? Or outside at the end?
    Is the garage holding up/retaining some garden?
     
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  11. Garryboy11

    Garryboy11

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    Hi. The ground outside front of garage Linda just continues on roughly the same gradient as the garage slope.

    This mirrors the house, if that make sense, ground is higher at back of house than front - for example crawl space under house towards the rear is only about a foot - at the front it’s about four feet.

    garage isn’t acting as a retainer wall for anything - other than a naff patio at the back which I’ve removed as it was causing damp (meant ground level was above garage floor level and currently there is no dpc in floor or walls).
     
  12. Tigercubrider

    Tigercubrider

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    It's worth digging at the back of the garage to check the foundations. Hopefully they go all the way down

    It's outside my experience but digging down might allow you to extend the footings for the back of the garage should needs be? I would assume best done before removing any of the floor? If you're lucky they dug a deep tench at the back and stepped the brickwork so it would be stable
     
  13. Garryboy11

    Garryboy11

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    I’ve actually dug a bit of a trench at the back wall of the garage already.

    As above the ground level here was above floor level and a patio/slabs had been built right against it.

    I’ve removed those and dug a trench.
    I think I can see the top of the founds.
    If that is them, it looks like there is only one course of bricks beneath the floor level. So maybe not a lot of scope to dig down.

    Sorry it’s not a great Pic
    upload_2021-6-7_20-17-1.jpeg
     
  14. motorbiking

    motorbiking

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    So for diligence, you want it strong enough to support a car and warm enough to be habitable. I think the cost of the polystyrene will be about the same as the concrete. A Kango is about £50 a day then a small skip to take it all away. If you can get enough out to get a sand bed, DPM, 100mm of poly and then a decent slab on top, you will achieve the goal. When it comes to selling.. two questions:

    - is there plenty of off-street parking and can you actually get a modern car to fit?
    - you just market it as a gym or outbuilding. Increasingly people are converting garages - particularly small ones.
     
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  15. Garryboy11

    Garryboy11

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  16. motorbiking

    motorbiking

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    If you are digging.. don't forget power and networking.. Much easier to get those cables in now.
     
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