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My DIY extension

Discussion in 'Your Projects' started by cdbe, 20 Mar 2019.

  1. cdbe

    cdbe

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    So I've finally made a start on my extension. It's a part double/part single 6m X 5.5m ground floor and 3.5m X 4.5m on the first floor on the back of my 3 bed semi. I will also be knocking through the back of the house and removing the internal wall between the back kitchen and dining room to create a large open plan kitchen/diner/family room with the obligatory bi-folds onto a patio. I'm also building a small 2 storey infill extension on the front to create a porch on the ground floor and convert the FF bathroom to a bedroom (with the bathroom moved to the back of the house into part of the rear bedroom with the remainder being partitioned off to create a corridor to access the new extension bedroom.

    I'm hoping to do virtually everything myself and am on it more or less full time.
    My budget is a little as possible.

    I have planning approval and am doing the work under a building notice. I have worked in the building trade as a youngster and more recently have done a loft conversion and a few back to brick house renovations, and actually have a HND in Building studies (which I expect will come in useful if I need any scrap paper for recording measurements etc!)
    Previously I have tended to dodge the building regulations approval side of things (tending instead to just over-engineer things) so that aspect will be new to me.

    I started my 18m of foundation trench on Monday and put in my building notice application. I dug a sample section 750mm deep by 600mm wide and was expecting (as it's clay) to be told to go down to 1m. BCO came out today, seems very reasonable. Said unless I wanted the exercise not to go that deep (we must have hard clay here up North, not that soft southern stuff). He said 600mm deep and to expose the existing house foundations and if they're higher just step up to them. Then he rang me about another issue and I said I'd exposed the existing and they were about 450 down. In that case, he said dig the rest to match - 450 is the minimum we'd accept for clay. Happy days - but I'm still going 600 down and stepping up to 450 at the house.

    Only thing he did say was that I need an SE on board straight away because there's lots of steel going in and any pads etc would be best done with the foundations.

    I will update and post some photos when the sun stops shining and it's back to rain as usual.
     
    Last edited: 20 Mar 2019
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  2. cdbe

    cdbe

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    So here's a bit of trench:
    IMG_20190320_155529434.jpg

    Here's one of the rocks I've dug out (some others were too big and only partially in the trench line so I've had to drill and chisel through them with the SDS):
    IMG_20190320_110917809.jpg

    Here are the existing house foundations - 3 bricks below ground level and about 30mm of concrete on clay!
    IMG_20190320_142706049.jpg
     
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  3. kingandy2nd

    kingandy2nd

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    You could make one hell of a rockery with those babies!
     
  4. Chunkytfg

    Chunkytfg

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    I think that definitely classifies as a Boulder!!!!

    Wow!
     
  5. Ian H

    Ian H

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    Nice trench!!! Have you got a drawing of how it will look when finished?
     
  6. Mrjollyjoe

    Mrjollyjoe

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    Why so deep with footings? you have sound clay just below surface if your into good clay you should be fine. If your in good clay here regs are happy at 2 foot, even if its not clay but its hard. Its more concerning if you in soft wierd crap or in fill, that looks good stuff.

    when you happy with depth try make bottom of trench flat it makes concrete stronger wirerd lumps can cause issues with strength,.

    (ops just read rest of your post!)

    good job just make it flat in bottom (y)
     
  7. cdbe

    cdbe

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    Hi Ian, I only have some basic stuff from the planning app:

    Existing rear elevation (the bit at the side with the french doors is a through garage):

    rear elevation existing.jpg

    Proposed rear elevation:

    crop rear elevation.jpg

    Existing ground floor plan:

    Ground Floor Plan Existing.png

    Proposed ground floor plan:

    gf proposed crop 1.png

    Existing first floor plan:

    ff existing crop.png

    Proposed first floor plan:

    ff proposed crop.png


    We had to make some compromises on the design to get the planning - the left hand wall along the boundary is only 2m high so we'll have a collared ceiling on that side, and we had to chop a metre out of the corner to meet the 45 degree rule for the neighbour. We also need to shift the bifolds over to the left (it's been kindly pointed out that they're too close to the corner for building regs) so will be deleting the window next to them.
     
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  8. cdbe

    cdbe

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    mrjollyjoe - I'd always thought it was a minimum 1m in clay - obviously not. I guess it's helped me doing the work under a building notice (and starting the trench before the commencement visit) so the BCO could see the ground and advise me. A few other extensions have gone up on my road recently and all seem to go down at least a metre - but they are machine dug and I suppose for a contractor it's easier just to be on the safe side so they can get the plant off site without worrying that the BCO will ask for another spades depth or whatever.
     
  9. Mrjollyjoe

    Mrjollyjoe

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    ha ha ive done 2 barns on building notices, they were not impressed with first but ok with second. You have excellent clay there should be sound footings.

    you could always move door to you new bathroom to make it on suite, if thats you new master bedroom, works well making that a bathroom/corridor.

    If you can do as much as possible you will save loads, labour is the big cost now, materials are ok its when you furnish it it gets expensive very quick, i.e carpets etc.

    Concrete it cheap in the grand scale of things so there no loss on depth, ive been lucky with good clay mostly but managed to fins a drain literally running along a footing once that was a big pain in arse as you cant bridge it.

    Keep up the good work thats a cracking effort for a hand dig, keep updating with pics!
     
  10. cdbe

    cdbe

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    I thought I'd update. Progress a bit slow as the digger has been out of action with an infected root canal! Trenches now all dug out, squared off and staked ready for concrete:
    IMG_20190404_142053408.jpg IMG_20190404_142057453.jpg IMG_20190404_142105494.jpg IMG_20190404_142115389.jpg
    IMG_20190403_072052836.jpg

    This photo shows the back wall of the house, which is all coming out on the ground floor apart from the bit between the windows which will form a pier to hold up the (seven!) steels supporting all the first floor walls):
    IMG_20190322_094801014.jpg

    As there isn't much in the way of foundation my SE has specified a 900x900x400 concrete pad to underpin this, so I've dug out the hole:
    IMG_20190403_115438310_BURST001.jpg IMG_20190402_173121731.jpg

    I booked the next BCO inspection for today, it rained all last night so I got up early and spent an hour hoovering all the water out of the trenches with my Karcher wet and dry - an amazing bit of kit for £42!:
    IMG_20190405_204430569.jpg

    BCO was happy with everything and gave me the go ahead to do the concrete. I asked him when I should get him back - he said "when you've got the roof on" which surprised me a bit but I suppose that's a building notice for you - it's up to me to get it right. Anyway he's agreed to come and check the ground floor build up before I cast the slab. Barrow mix are coming on Monday - I reckon between 3 and 4 metres at £138 a metre (much as I like to do everything myself I couldn't mix it for much less).
    In the meantime I'm trying to decide whether I can get insulation plus slab plus a bit of self levelling compound flat enough to form a finished floor base or whether I need to do slab-insulation-screed, and working out a plan for the heating pipes under the slab, and remembering to extend all the airbricks.
     
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  11. Mrjollyjoe

    Mrjollyjoe

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    Looks good nice neat job,

    dont under estimate how much concrete you footings will take and how heavy it is to move get plenty of people, wheel barrows showel rakes etc to flaten it out.

    also make sure wagon has plenty on to mix.

    my neighbours a lemon and had to barrow about 5 cube with no under standing of how difficult this task would be around his whole house..

    it was hard enough with 4 of us in a barn floor and the wagon was dropping it into the pad,

    my advice get plenty of help makes job much easier.
     
  12. cdbe

    cdbe

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    Concrete done today. I was there with my wellies and rake expecting a right slog but it was the easiest thing I've never done. 2 muscular Barrowmix guys with long arms wheeled in 3m in less than an hour, I left it till the water rose to the surface then just raked it about a bit till the "puddle" was evenly spread over the surface. Should be good enough to build off with a thick bed.

    It cost £414. To mix it myself would be 6 bags of ballast @ £40 plus 40 bags of cement @ £4.50 = £420 plus 7 trips with my trailer to get the stuff - it's no good getting it delivered as they just drop it on the grass at the front - I can just about reverse my trailer up the driveway and through the garage with 1 jumbo bag in it.

    IMG_20190408_124706566.jpg IMG_20190408_124651244.jpg IMG_20190408_121214297.jpg IMG_20190408_121159828.jpg IMG_20190408_121154999.jpg

    After the holidays I'll start building up to dpc. Because the adjacent ground level is so high I'm surrounding the perimeter of the extension with acco drain so I need to think about how that will work - I'm thinking of backfilling the outside of the trench with a weak mix of concrete (mainly consisting of the hundreds of stones that came out when I dug the trench) and sitting the channels on that.
     
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  13. pilsbury

    pilsbury

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    Aahhh! This takes me back. Looks good so far. Surprised at how little concrete has gone in there.

    A nice tidy site too. A tidy site is a happy site. I never got the hang of that.

    Keep the pics coming. It’s great to look back on.
     
  14. Benway

    Benway

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    Good luck and well done with the hand dug foundations! What's with the chunk out the corner?

    upload_2019-4-8_23-15-58.png
     
  15. Motman

    Motman

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    Nice work. I can still remember the slog from when I hand dug 1m footings for my front extension. Architect didn’t show a neighbours tree on the plans so when building control came round to inspect footings he gave me a chart and according to my soil, the type of tree and distance, I would’ve needed to go down to 2.3 metres for at one end for just a 1m single story extension! He suggested it would be easier to remove the tree before he passed it off and plant a new one afterwards which, luckily, my neighbour let me do.
     
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