A retaining wall probably isn't entirely necessary, as the worst that would happen is it collapses down against the workshop wall. However that would eventually lead to damp.
If you put in a retaining wall, it stops moisture being held against the wall, and should stop moisture soaking through the wall.
We got a builder in to do the conservatory but I did do quite a bit of the work myself. The concrete pour wasnt really difficult. Started at the middle and worked out from there. The hard part was walking about in the concrete while pouring it and trying not to fall in it!
How close are you building to your boundary? Can you build the retaining wall at the boundary and leave say enough space to lay a row of 450mm slabs around the workshop for maintenance access?
about 600mm from the boundary at the back, 900mm to the LH side. My problem is that adding a retaining wall adds another 300mm to the dimensions and already SWMBO isn't too happy. I think I'll see if i can take it back further, but I cant go any further left because of a laurel bush that I want to retain. If I can level it more on the left and leave just the need for a rear wall and grade the RH side a bit that should be OK. Else I'm looking at £700 of sleepers to make a wall, but at least that won't need a concrete foundation, just some post-crete'd holes. A poured concrete wall is another option at only .7cu m of concrete (100mm wide at top, 300 at bottom, 4.1 m long, 800mm high) but needs some complex form work and wouldn't look so nice.
A concrete wall will look fine with a bit of roughcast on it and some flag stones on top. Seeing as your getting the concrete anyway you need the foundation and shuttering.
Well end of day 1 and not entirely to plan. Digger didnt turn up til gone 10 but I'd spent the first couple of hours chopping up a crazy paving path that cuts across the corner of the dig. With a cold chisel, a 5lb club hammer and the bosch power chisel... hard work... if I'd known how difficult I'd have hired a kangol but i would have only needed it for an hour or so... then the Muck Truck (powered wheelbarrow) got stuck in the garage back door.. the gap was 705mm the muck truck was supposedly 680mm... yes apart from the hubcaps which needed another 30mm, so had to take the door off...
Anyway, dug out about 1/4 of the area at the deepest end, down to 730mm or so... will finshing digging the rest before doing the final 100mm just in case my land surveying is a bit off...
will put up some pics later when I've eaten and dragged them off the camera... but here's the boys toys taken on my phone...
Day 2. Digging continues... couldn't start making noise til 9:30 cos SWMBO said it wasn't neighbourly, so was out to Wickes at 7:30 to get a 1800mm spirit level, a folding builders square, and a six pack of 2 x 2 to make stakes from. Had my youngest son helping today driving the barrow so that made it faster, tho the amount of damage to the garage back door frame does make me question that... I was planning to replace that door with a uPVC one sometime as the door itself is going rotten - so might be sooner than later, well have to order doors/windows for the workshop so whats one more door lol (about £250 or so in case you were wondering). Masses of tree roots made digging slower than hoped, each one having to be chopped several times, the digger isn't man enough to lift a 3" dia root and there were about 2 dozen of them under the surface (and still more where I've not yet dug I'll venture). Really needed a chain saw, the circular saw can't handle living wood well, so really only had the mattock/ax and that makes it hard work...
I'm hoping tomorrow will see the end of the digging out, leaving Monday for levelling and tidy up of the sides... at least the digger is in the hole now, was a scary job driving it down the short ramp of earth. Apparently I should leave a ramp in then dig the ramp out after, but that makes it harder, esp as the only place to put the digger will be in a bush I want to keep. I'm thinking 6 pieces of 4 x 3 on end to make 4 x 9, 2.4m long with some 2 x 2 spacers will make a couple of ramps @ 12% (is 4 x 9 overkill for .9ton?) and they can be reused for the shuttering or the out of sight framework for the benches.
Decided to go for a concrete retaining wall, with some extra mesh in it and a DPC between it and the earth, and I'll bury a land drain pipe behind the dpc.
Now, how do you fix a concrete fence post? managed to catch one with the digger when I got confused with my levers :( and it cracked about 6" up from the base... I guess I need to get a new one but how do I get the old one out?? I'm wondering if the digger will lift it out with its cement block... assuming it was post-creted...
Well, just an update... today sees the completion..... of the hole...
Even with the digger and the powered barrow, this was a task I seriously underestimated.
Firstly, 1 foot or so down and we hit London Clay... initially that was easy to dig, like spreading butter, but once exposed to the sun it turned into concrete. Even harder were the deep patches of water-worn stones embedded in the clay. Sadly no fossils though I did break open some likely looking nodules of flint.
Then it rained, albeit briefly, on Wednesday night. By Thursday morning my hole wasn't looking like a swimming pool as I feared but the clay had gone all gloopy and walking on it meant you sank in about 2". It was unworkable for a couple of hours til it dried in the sun and then it was unbreakable :(. But I persevered. Damp clay is incredibly heavy so I found I could only half load the barrow else I couldn't manouver it. So now I have pile #2 in the drive (pile #1 was removed by grab truck on Monday) - something like 17 tons of earth has been shifted, all on my own.
All the wood for the shuttering is now sitting on bricks under a tarpalin, so will assemble that this weekend in sections and do a trial fit. Then have to order the reinforcing mesh and the ballast and sand. No powered barrow this time so willl have to manually shift it all, but theres a lot less of it... biggest problem now is finding the time.
Here's the design of the retaining wall to go across the back.
Well the hole is done...
A second grab truck (same firm) removed pile #2 today. Both piles have gone to be landfill to sculpt a new golf course in South Mimms. (not a bad business this grab trucking... you get paid to take it away and paid to deliver it on the same day lol)
This is before I cleaned it up and tidied the edges... its 6.34m x 4.14m and 275mm deep in the nearest corner, 800mm deep at the far lh end. The bottom is flat to within 3cm which I reckon is good enough.
loks awesome, can't wait to see it all done and your machines in there.. keep up the good work
Irving, its amazing how fast you work, from drawings to actually getting started. I suppose when there's something on your mind and you're thinking about it all day, things get done. Keeps the pics coming, its a very interesting thread.
I'm surprised your other half hasn't told you to keep digging and make a swimming pool instead, lol forget the shed and concentrate on relaxing.
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