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Garden Office

Discussion in 'Building' started by MrFish1968, 20 Jun 2018.

  1. MrFish1968

    MrFish1968

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    When I move I am thinking of building a garden office so I don't need to use space in the house for that.
    I'd like to use Celcon 630 x 215 x 100mm blocks for speed of construction, and once I have the 1st course level and plumb I believe it is very easy to keep that all the way up using thin joint mortar. It will be below 2.5 meters tall, and will be no more than 12 sqm max, and it will be a simple rectangle shape. Single double glazed door, 2 double glazed windows, then metal studs inside for walls and floor, and insulated using the closed cell spray foam, similar in ceiling. So I think with the Celcon blocks and closed cell insulation I have the thermal and acoustics covered, plus vapor.

    The one thing I am unsure about is is the 100mm wide blocks, will that be stable enough?, i.e. I don't want it falling over? I also don't want to build piers as it will be pretty small anyway. If it does need to be shored up somehow I was thinking 40x40x4mm hollow box mild steel posts at each corner going about 1 meter into the ground, and these would be filled with concrete for extra strength, then I'd notch out a 40x40 space on the blocks at the end so they go aroud the post, alternate this on each course so every thing is tied nicely to these posts, I'd then probably add 1 more down each side, offset from each other. Probably also tied the top together with the same stuff so the roof can rest on that, which is just a simple roof with a slight gradient for run off. Then render the outside with a waterproof through colour render.

    Any of this feasible? Or is there a more simple way of make sure it doesn't fall over. I'm not too worried how long it takes, as I can take my time. I just want to make it nice looking and secure

    Also, I'm pretty sure I don't need planning permission, but I would like a building control cert if I ever sell the house.

    Also, the garden is about 120 smq, so it is pretty small with regards to that.

    Also, example of what I mean by the notches, and steel posts, I think this should tie all the walls very nicely together, and add a lot of sheer strength.
     
    Last edited: 20 Jun 2018
  2. MrFish1968

    MrFish1968

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  3. ^woody^

    ^woody^

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    There are thousands of houses up and down the country with thousands of garages of similar construction to what you describe, and they have not fallen over. No steel posts either.

    You can't get a building regs certificate unless the regulations apply.
     
  4. nickjb

    nickjb

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    You'd never be able to cut a notch like that in a lightweight block without it cracking, luckily its not needed. A squarish building that size won't need piers either. Just build it, it'll be fine. Its also small enough to be exempt from building regs so won't matter when you sell. Any electrics will need to be signed off though, either by a self certifying spark or via building control.
     
  5. Notch7

    Notch7

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    Have you checked availability of thin coat materials?

    I doubt if merchant carry stock.

    You will need the first row of blocks off the foundation to be set on mortar and set spot on level.

    Its an interesting way to build a garden office -if you do it, we need pics (y)

    Personally for a small garden office, I would go for timber stud construction. Timber frame, keeps the wall thickness down but also a cavity can be included but is only 25mm thick -if the exterior is timber clad, or even renderboard.

    With blockwork you will be needing to clad both interior and exterior to get a finished building, the wall thickness and the costs could mount up. And the disadvantage of no cavity unless you counterbatten and clad the exterior.
     
  6. MrFish1968

    MrFish1968

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    I’ve jist found ytong blocks, they do a 440x215x300 high strength block with great initiating and acoustic properties. And with a 300mm width that would be solid! £59 per square meter. These blocks are also meant for thin set applications. The plan was to render outside with waterproof through colour k-rend, and a small 50mm stud internally with either 25mm celotex, or the closed foam spray.
     
  7. Ian H

    Ian H

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    But you will loose 400mm of space inside using a 300mm block. That's more than the 100mm blocks plus piers.

    I'd stick to 100mm blocks, no piers and let the roof add any extra support.
     
  8. MrFish1968

    MrFish1968

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    It only want about about 3 x 2.5 meters internally. And the back garden is 150sqm so it isn’t too bad.

    How does the roof add extra support? Noob.
     
  9. Ian H

    Ian H

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    It has the wall plate strapped to it all round then the rafters/ceiling joists nailed to that.
     
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  10. MrFish1968

    MrFish1968

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    At 3.6N will that be OK at around 2.2 meters high. 10 x 215mm bricks high? They are fairly light at around 6kg.
     
  11. ^woody^

    ^woody^

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    PM me your address.

    If it goes tits-up with Putin, I want to be sitting in that "office" so that I get a guaranteed head start with the post-apocalyptic extension business.
     
  12. Ian H

    Ian H

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    I'd say so it I'm no pro. The way I see it is that nothing will be too far from a corner and the corners are very strong.
     
  13. MrFish1968

    MrFish1968

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    Yeah, I think I'm over panicking. So the ytong blocks with thin joint mortar, first course with proper mortar to get plumb and level so the rest are quick and easy. 440 x 215 x 100mm blocks, they seem easier to source but I'd rather use the 610mm blocks.

    100mm x 75mm c24 treated for the wall plate on top, strapped with the 2.5mm metal straps to the wall, I only need to 3 degree slope for run off, so 3 of those at the front to give me 3 degrees pitch.

    Loose laid insulation floor inside, 40mm kingspan floor insulation, 3mm screed on top of that, felt, 18mm T&G chip board, 7mm carpet tiles on top of that.

    Inside, walls 40mm studs, c16 grade (belt and braces), sprayed with 25mm of closed cell foamseal, plasterboard over the top, ditto the ceiling.

    I don't think I need a vapour barrier as the closed cell foam does the that job, I think, I was thinking of the same spray closed cell foam on the floor, but I wanted to avoid framing, but if I did I'd update use metal studs.

    Outside all covered with 2 or 3mm of k-rend through render, waterproof, so all good.

    Should come in at just shy of 2.3 meters at the tip of the pent roof.

    It will sit on a 150mm concrete slab, usual compacted MOT 2, sand underneath that, is it quite a clay area so I think 150mm is the norm.

    Thinking about insulating that, is it needed? Also, can I just use a paint on DPC instead of the roll? I'd rather use that as much as possible.
     
  14. ^woody^

    ^woody^

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    If you think getting the first course plumb and level means the rest of the wall will be, you've been watching too many "The Bricky" videos.
     
  15. Ian H

    Ian H

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    I got that far then you lost me with the using 3 for a 3 degree fall and the 3mm screed, I'm not understanding those bits.
     
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