Upwards Garage Extension

Discussion in 'Off-Topic Discussion' started by Freddy, Mar 15, 2018.

  1. Freddy

    Freddy Miserable git, well known for it

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    Hiya folks.
    Just looking for some info at this stage. My adjoining garage is double skinned, but no cavity. Assuming the foundations are good/conforming, would it be possible to build upwards to create extra accommodation? Is there some way to create a cavity in the upper part?
    Cheers...Freddy
     
  2. Loofah

    Loofah Admin Staff Member

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    You certain there's no cavity? If no then I would expect a rebuild ground up but the footings probably aren't suitable for a two storey build in any event. You might get away with underpinning.
     
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    • Doghouse Riley

      Doghouse Riley Head Gardener

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      Building regs. regarding footings have changed over the years.

      Our houses in this small estate were built on concrete rafts. There's never been a problem with these nearly 100 houses.

      We wanted a small single storey lounge extension in 1976, but our builder was made to dig down over six feet until he hit sand before the footings were passed.

      Might be an idea to have a word with your local council.
       
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      • JWK

        JWK Gardener Staff Member

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        Shouldn't be a problem Freddy. If there is no cavity it will be a case of adding extra insulation internally to conform to Building Regs. I had my garage converted a few years ago and only have a 75mm cavity (100mm or 4" is the norm). To get mine approved I used an insulated plasterboard, something like this:

        Gyproc Thermaline Super Tapered Edge Wallboard - 2.4m x 1.2m x 90mm | Insulation Superstore®

        It means you lose space internally, I bought more expensive stuff as thin as possible to avoid that. You will obviously need it specified by an architectural technician but it is easily do-able.

        Depending on how it looks externally you may be able to use external cladding, e.g. if your extra room is facing next doors and not visible from the street.

        Another way would be to build a cavity wall above and is possible (for basements for example where the first floor is solid for retaining purposes). In your case your existing lower floor will only be two bricks wide, a cavity wall is three bricks wide. So I can't see how that would work.
         
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        • Freddy

          Freddy Miserable git, well known for it

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          Just checked. The front is definitely just two layers of brick, but having measured the width at the doorway, it measures around 11” including the render, so there is presumably a cavity along the length.
           
        • JWK

          JWK Gardener Staff Member

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          Hi Freddy you can tell if it's a solid wall or not by the brick bond:

          upload_2018-3-16_13-4-35.jpeg

          Also roughly when was the house built? They started to be first used during the 1920s.
           
        • Scrungee

          Scrungee Well known for it

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          Not necessarily, some cavity walls are constructed with the same appearance as a one brick wall in Flemish bond as above image, but are built using stretchers and snapped headers on the outer skin. Some solid 'one brick' walls are constructed using 2 skins of stretchers tied together with wall ties with eithet a mortar joint or narrow cavity in the middle (to accommodate the wall tie 'twists). The reasons for such construction is usually to provide visual continuity of bond with adjoining brickwork.

          So both bond and the overall thickness are required to work out what method of construction has been used.
           
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            Last edited: Mar 16, 2018
          • Freddy

            Freddy Miserable git, well known for it

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            Hiya John :thumbsup:
            This is what I have at the front...

            8D909AB9-A507-4C5F-982B-EEF359BF5057.jpeg

            The rest is block and render/spar.
            The house was built mid-70’s I believe. The garage extension was built later on.
             
          • JWK

            JWK Gardener Staff Member

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            It's stretcher bond pattern and given you said it is 11" thick then it's definitely got a cavity, but maybe a smaller cavity than would be specified now.
             
          • Freddy

            Freddy Miserable git, well known for it

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            A bit of a misunderstanding, it’s 11” along the length, not the front as per image.
             
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            • JWK

              JWK Gardener Staff Member

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              I'm not quite with you, which is the length and which is the front.

              To avoid doubt Freddy, just open the garage door and measure the depth of the wall i.e. front external side (facing the road) to internal garage side, so for the image below it will be approx 302mm or nearly 12" - so does that confirm which dimension you measured?

              [​IMG]
               
            • Scrungee

              Scrungee Well known for it

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              Often there's piers either side of garage door openings, and any projection of those would need deducting from the width of the reveal.
               
            • ricky101

              ricky101 Total Gardener

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              Hi Freddy

              Assume you mean you want a habitable ground floor as well as the new first floor ?

              The first thing you need to establish is the size of the footings, which means digging down on the outside to expose and measure its depth and to some degree its width.

              Depending on what you find you will need professional advice as to what loading the existing footings can take.

              Until you do that anything else is irrelevant .


              If the builders were taking short cuts or the garage footings were not part of the house footings pour they might be much smaller to take the load of the garage only.

              Also the garage floor, is it just a concrete slab on the ground without any damp proof or insulation ? a problem to overcome if its not.

              Are you intending to do all the build yourself ?
               
            • pete

              pete Growing a bit of this and a bit of that....

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              If I was looking for a cavity, I'd drill a hole ;)
               
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              • Freddy

                Freddy Miserable git, well known for it

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                My apologies John for not coming back sooner, I’ve been re-discovering the joys of door hanging :gaah:

                The front is as pictured, the length is down the side, not pictured.
                The front is one brick thick, so around 9”. The side wall is around 11” thick, so presumably a 3”- 4” cavity.
                 
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