Whats good for removing clay soil for conservatory foundations?

[Fat Tone]

I'm having a conservatory added to my house, and after getting quotes it looks like I'm doing virtually all the work myself, with help from family.

There is a patio to the rear on which we are building, adjacent to which is a raised lawn. The conservatory is bigger than the patio, and so far I have removed all the excess lawn (and the retaining wall) down to the depth of the patio. This was a lot of earth - ~5m by 1m by 0.5m deep and a few deep-rooted trees. The next step is to dig trenches for footings for the new retaining wall and the perimiter of the conservatory (3.5m x 4m).

The soil is now very heavy clay so I'm looking for some sort of power tool to ease the work. I don't mind shifting the soil, its just the extraction that is tricky. I'd rather not hire a minidigger, but maybe some sort of breaker/trencher?

I don't yet know precisely how deep to go, so any experts on conservatory bases and walls please let me know! One wall of the conservatory will be 1.8m high, the other two will be 0.6m high.

TIA.

[cjolley]

conservatory?
Is that like a greenhouse?

About the only powered tool smaller than a trencher that I can think of would be a gas powered posthole digger.
Just punch a bunch of holes and dig out between them.
But man that would be a lot of work.
Still, if it's tight clay it might be easier than straight digging.

[Fat Tone]

A conservatory is a home extension that is mainly glass, usually with a polycarbonate roof. See http://www.conservatoryland.com/conservatory/index.html for examples. Often a low wall perimeter is built on which the frame sits.

I've seen one hole borer, which could work, but because of the long lever it might not reach about 3-4m of the 12-16 I have to do. I say 12-16 as the retaining wall and the conservatory are only 1-2 feet apart so could share a footing. Not sure yet.

[klc314]

If you can afford it, it might be worth having a geo-engineer design it for you. There's a lot of stuff going on, and the depth of the footing depends on your local freezing conditions. You want the bottom of the footing deeper than the freezing level, so the earth won't buckle when frozen underneath the footing. The other issue is the earth retention, which needs some footing back underneath the retained portion, so there is weight bearing on the footing, kind of like the letter "L", to keep the wall from falling over. In addition, you need to know how to keep hydraulic pressure from ground water from pushing on the wall, so some way to carry off ground water around the wall. Difficult to explain, a little research on retaining walls might produce some drawings of what I'm trying to describe. All this is worth it in the long run however.

[cjolley]

You can also substitute, additional rebar, fibermesh, and higher strength concrete for some of your digging. NB: These are not interchangeable, they each solve a separate set of problems.

Also, dont forget to ask for an air-entrainment agent in the concrete.

[cjolley]

A conservatory is a home extension that is mainly glass, usually with a polycarbonate roof...

We would call that a sun-room.
I am envious.

PS Please don't tell Becky you are doing this yourself.
Last time something like that happened I had to dig a base, fill with sand and lay 4 tonnes of flag stone patio.

[Fat Tone]

Once I've made the holes, I'll look into what readymix is available vesus mixing myself. I have access to an electric mixer (not a food processor ). Unless you want to pop over and pump some crete for me?

To give an idea, here a pic of the patio yesterday morning and now:

The retaining wall just had a couple of inches of concrete below it, with a polythene sheet on the rear. The patio gets little sun at ground level, so we are happy to lose that space even though the garden is not very big. The poly roof should let plenty of sun in though.

[cjolley]

Will the floor be concrete?

[Fat Tone]

Yes, with some insulation too. may have to lift the slabs to get the height.

Was just browsing through a local hire-firm catalogue and came across an SDS drill accessory called a 'clay spade', simillar to http://www.toolbarn.com/product/bosch/HS1922/. They are a lot to buy but only a few quid to rent and I already have an SDS drill. Hopefully this will help somewhat

[GNEP]

See if you can hire a mini JCB (the really little ones with the small caterpillar tracks - I think they call them mini- and micro-excavators). Makes light work of a job like this (especially if you have the place you are dumping the spare clay close by). And also great fun little machines to drive and operate. I've done foundation trenches with one of these in a fraction of the time doing it even vaguely by hand would take. May be not too expensive to hire one for a weekend - as the trade shouldn't be using them then. And if you have a contact, do it through a construction firm to get max discounts and so on.

[KRSESQ]

Yeah, something along the lines of this product by Melroe Equipment would make short work of it.

Kevin

[Sasq]

and there I was just thinking use some C4, maybe not practical, but at least its fun

as Keven suggested, and we call them a bobcat in oz, something along those lines would make short work of it - and they are almost as much fun as the C4

[KRSESQ]

Hey, we call 'em "Bobcats" here too! In fact, we make 'em here at the local Melroe Bobcat plant which is now owned by Ingersoll-Rand.

(In fact, a few of my clients work at the plant and have probably laid down welding beads or torqued bolts on most every Bobcat sold WORLDWIDE within the last ten years!)

What's nice is, they require little or no specialized training to operate (I'm living proof of that!).

The Melroe Bobcat website.

Kevin

[gt40]

Yeah, they call em Bobcats here as well, and they are really not that expensive to rent for a day.

[KvHagedorn]