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Retroanaconda

New workshop project

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The ground does seem pretty good from what I've seen so far. I'll be putting steel in the slab for sure, probably two layers of mesh given it'll most likely be a 150mm slab. Unfortunately laying the sub base first and then digging out around it wouldn't work as on the low side it would need to be 150mm or so above current ground level in order to get the slab at the right height, and so would need retention of some kind anyway.

If I simply battered the excavation and sub-base I would end up with a slab of variable thickness across the site. Not sure if this is a problem though? Would obviously cost a bit more in concrete as you say but that's no major issue if it saves work elsewhere. This essentially does away with the idea of the 'walls' and incorporates them into one big mass concrete slab, and would certainly be the simplest method of construction. I would end up with something like this:

1.PNG.85ceac777279a980367dc0c3a1f3583d.PNG

I think realistically I need to break ground on it and see what I'm dealing with before I can design the thing properly - so once the planning is (hopefully) through I'll book a week off work, get a digger in and start making holes :i-m_so_happy:

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That is a lot of concrete - and the boxing will be under some serious pressure from the weight... Have a look - we used 6 IBC's filled with water to support the 40 cm. box to keep the concrete in..

I'd level it out with the sub-base (we use a sort of gravel for that) and pour a 10 cm. concrete slab with rebar..

Should be fine - and less expensive..

We used a few box sections in our ABRI just in case we want to build up the the walls with concrete blocks..

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My instinct tells me that pouring concrete on a slope is a bad idea, I have had shuttering move on me twice in life and it is a tough problem to deal with when the lorry is waiting. Levels and steps is better, or one big step at the back as you had above, I wouldn't bother with the interior shutter though, just a reasonable angle of repose would be fine. Don't underestimate the counter force needed behind that deep shutter at the back,..... maybe move all the spoil there and build a bank behind the shutter?

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Thanks. I'll probably go with the stepped option, as long as I can get the levels correct.

Good news is the planning permission is through so I can crack on, as soon as I have some time.

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Good to have the permission - now the hard work can begin...

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Started clearing the site this afternoon, the various bushes had an appointment with the chainsaw and were removed, releasing about seven billion midges in the process. A trip to the dump tomorrow will see it gone.

3266CE7A-21EB-4351-B72A-B9DF91A400E8.thumb.jpeg.89317c5c8e19b1313874e2ea7646333b.jpeg

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The large grand fir behind the fence needs to come down too, but I’ll wait until the oil tank is moved before I fell that.

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Are you taking the fence out and ‘replacing’ it with the garage walls?

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No - the walls of the garage need to be about 300-500mm inside the boundary in order to allow for the eaves and the gutter to stay within my land, plus to facilitate access for installing and maintaining the cladding.

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Some more very slow progress, but I moved the oil tank yesterday. The fence will actually come down as I’ll fell the tree into my garden and not my neighbours, however it’ll probably go back up again afterwards.

D2F6FDFA-03E3-47FB-B880-604E12DA5472.thumb.jpeg.4a3d9ae0856dd127f4f1634c1657ba09.jpeg

 

I don’t think I’m likely to have a problem with soft ground, digging the trench for the new oil supply pipe today I was mostly removing slate rather than soil. Bloody hard work, but good to know that there’s very hard and free draining material under there. 

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It would need to come down regardless as excavating for the foundation would compromise the roots on one side and greatly increase the chance of it blowing over onto the neighbours house or cars. Plus the potential for the roots to damage to the structure of course.

Happily they want it removed anyway so that solves both problems.

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If you need building regs for this be aware that the proximity of trees (even recently deceased ;) ) will impact on the required depth of your footings. Chat with your building inspector before pouring anything.

I only know this as one wall of my new garage has 2.1m deep footings...... :o thanks to the building inspector......

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11 minutes ago, bishbosh said:

If you need building regs for this be aware that the proximity of trees (even recently deceased ;) ) will impact on the required depth of your footings. Chat with your building inspector before pouring anything.

I only know this as one wall of my new garage has 2.1m deep footings...... :o thanks to the building inspector......

2.1m 😳. How many storey garage is that for? 

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Our builders said they knew the inspector would always find something to pick them up on, often the depth of footings, so they always dug them a bit shallow so the guy would come round, tell them it needed to be 6" deeper or whatever he thought, and then they'd end up digging them to the depth they were going to dig anyway :lol: everyone's happy!

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My (perfectly ordinary, single storey) garage has considerably deeper foundations than the 30ft gable end of the house next to it. Which has been standing up perfectly satisfactorily for over a hundred years.

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My parent's place has 18" foundations, if that, which is a stark contrast to the extension, which has 1800mm, and built in the 90s.

I have often wondered whether the house will slide down the hill, leaving the extension where it is :D

 

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I was helping someone do some work at their age old cottage, think hand made bricks and ranges, turns out there's no footings at all. dug down a couple of courses of brick and that was it, straight under the house, no footings at all. The area is mostly sand too so I guess you fine so long as it's flat and doesn't flood :wacko:

In comparison the pads they made us put down at the factory where I work were unbelievable. OK the steels hold up the factory roof and overhead hoist but I don't think there's that much concrete on a rocket launch pad. I pity anyone who has to dig it up.

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On 4/26/2019 at 5:27 PM, Retroanaconda said:

The ground does seem pretty good from what I've seen so far. I'll be putting steel in the slab for sure, probably two layers of mesh given it'll most likely be a 150mm slab. Unfortunately laying the sub base first and then digging out around it wouldn't work as on the low side it would need to be 150mm or so above current ground level in order to get the slab at the right height, and so would need retention of some kind anyway.

If I simply battered the excavation and sub-base I would end up with a slab of variable thickness across the site. Not sure if this is a problem though? Would obviously cost a bit more in concrete as you say but that's no major issue if it saves work elsewhere. This essentially does away with the idea of the 'walls' and incorporates them into one big mass concrete slab, and would certainly be the simplest method of construction. I would end up with something like this:

1.PNG.85ceac777279a980367dc0c3a1f3583d.PNG

I think realistically I need to break ground on it and see what I'm dealing with before I can design the thing properly - so once the planning is (hopefully) through I'll book a week off work, get a digger in and start making holes :i-m_so_happy:

Remember you'll need 50mm cover over your rebar top and bottom. we used to design slabs like this with 2 layers of mesh, one running 50mm from the top surface and one 50mm from the bottom surface all tied with spacers. Are you going for brickwork walls or is a steel frame/timber frame workshop? if it's the latter then I'd spend a bit of time casting in studs for the feet of your frame. Much easier than post-drilling and hitting rebar with your drill bit!

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No need for a building warrant luckily so don't need to worry about that. It will be a timber framed building, but there will be a dwarf wall of engineering bricks around the outside two courses deep and the timber frame will be anchored to that. Either via fixings directly through the sole plate into the bricks or via straps on the inside face, not sure yet.

The mesh will have 50mm of cover, either one layer in a 100mm or two in a 150mm slab. If the ground is as good as I hope it will be in terms of load-bearing ability then I'll likely get away with 100mm of sub base and a 100mm slab given the light-duty nature of the building, but I may as well make up the slab to 150mm just to make the concrete better value.

I was also mocking up the front end at the weekend and I may be able to get away with side-hung doors after all by having one smaller one that folds flat against the building as suggested earlier in the thread, as there's a bit more space than I thought. Which would save on the (quite considerable) cost of a roller-shutter door.

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Have you any restriction in the height of the building James?

Im thinking given the cheapness of 2 post lifts this days, if you’ve got the ceiling height, worth considering when you do the concrete 

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Only in terms of what I’ve got permission for. A lift would be nice, but it’s never going to be big enough to have space for a lift and a normal flat area.

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That’s why I was thinking 2 post.... almost free floor when not in use. 

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Apart from the two ruddy great posts of course?! :P

If I did have a lift it would be a four post anyway.

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