Concrete mixtures

[Christian McArdle]

I need 4m3 of concrete. If I spurn readymix and buy the ingredients, what weights (in kg) of aggregate, cement and sand do I need?

Christian.

[Christian McArdle]

A builder friend of mine said that we'd get the lot done in a day, with sufficient help. Unfortunately, he's gone off for a bit, so I'm just trying to get some rough costings for comparison before I make a decision. The readymix is complicated by the fact that it would need to be pumped round the back. It will cost about 800 quid due to the additional cost of pump hire. I can probably cut back to around 2.5m3, if I reduce the slab thicknesses a bit. I was planning 200mm for the conservatory and shed, but

150mm for the conservatory and 100mm for the shed (with 150mm footings) might be enough. Carrying everything through the house will be fun, though. I'm still not convinced we'll get the mixer through, even totally disassembled.

I'm still a little sceptical myself, but then he did build a concrete slab for an extension a few decades back using only a spade. He also built a huge extension on the back of his house using only the mixer. His daughter is apparently a wizard with the tamping beam...

Christian.

[Niel A. Farrow]

I priced ready vs mixing myself and some quotes were less than mixing myself, and this didn't include buying/renting a mixer and seing a physio. If you do want to do it yourself, and that's about 70 smallish mixer loads, phone your local builders merchant and they'll tell you what you need and also deliver it. Neil

[Mark Spice]

As my Dad was an owner-driver of a readymix lorry I spent a large part of my childhood around building sites. In general if there was nowhere to dump the excess on site (eg if on a large estate or building site) it tended to be taken back to the depot and dumped in the old quarry. That is if Dad didn't have a project on at home (eg paths, drives etc) in which case he would take it off their hands....

I would check before ordering though and try to order as little as possible.

HTH

Mark Spice

[Christian McArdle]

There would probably be four of us. One feeding the mixer, one laying, two tamping. I probably get the bum job of feeding the mixer, as it's my house. It will involve shifting many tonnes of building materials through the house.

Christian.

[Christian McArdle]

I can't use a wheelbarrow. Pumping would be the only solution for readymix. You've got 20-30 minutes to empty the truck.

You find something else to do with it. Lay shuttering for a base for a patio if there is enough, or tip it in the gap behind the shed.

Christian.

[David]

I once had a uni holiday job in the 80's driving a minimix lorry - this company had a flat-backed Transit van upon which sat a small concrete mixer - ie, a mini version of a Readimix truck. I think it used to deliver something like 0.5 or 1.0 m3 at a time. The great thing about it was that whereever I could back a Transit van, then I could drop a load of concrete - typically up someone's drive for a garage base or into their back garden for foundations of an extension, which negated the need for lots of barrowing or installing piping. Obviously there was a premium over the cost of a Readimix delivery as I could often be running back and forth to a single job all morning, but the punters reckoned it was worthwhile in saved effort.

I have occasionally seen small minimix trucks around since then - worth considering tracking down for appropriate jobs?

David

[Grunff]

You know what I'd do? I'd crane it in. Seriously.

I'd hire a crane for a couple of hours, same as I would if putting in an RSJ. I'm sure they'd be able to supply a suitable hopper.

[Christian McArdle]

I can't even get a wheelbarrow to the back garden, let alone a Transit. :-(

Christian.

[Toby]

I've found local minimix firms to be way cheaper than RMC, even if a bit unreliable about turning up on time. The material costs of DIYmix seems to be about the same as a delivery of readymix for about 2m3 round here.

To answer your question,

says you need

4m3 C20 concrete: 1280 kg cement 2400 kg sand 4800 kg gravel 1200 litres water

Toby.

[PoP]

The way some "white van man" types drive I wouldn't bet on it, you might be able to get one of them to get the transit into the back garden ;)

PoP

[Christian McArdle]

The cement is in bags. The rest would have to come through in buckets. You can see why the pumping idea appeals, despite being double the cost.

An additional door wouldn't help. Removing the stairs would improve access to the rear, but might have deleterious affects on access to the upper floor. ;-)

Christian.

[Owain]

"Christian McArdle" wrote | An additional door wouldn't help. Removing the stairs would | improve access to the rear, but might have deleterious affects | on access to the upper floor. ;-)

Just remove the bottom few steps and put down some little railway tracks. Then pull buckets to and fro on ropes. (Just don't get caught pulling up the hall carpet or you'll be in trouble with the Kommandant!)

Owain

[serrac]

You might want to check these out as an alternative to all that concrete....

have any experience of these systems? I'm thinking of using one for my conservatory and am interested in any comments.

regards

serrac

[Toby]

If you can't barrow through from 1 ton bags, then 25kg bags of materials is not going to work out cheap. Over £400 plus mixer hire.

Plans B, C, D etc. Rear or side neighbour in exchange for a new fence? If you can't get the concrete round the back easily then don't build a slab, not essential for a shed. If a wheelbarrow won't fit, will conservatory parts and roof sheets? Steel base frame on pad foundations will be sufficient for a modest conservatory.

Toby.

[Christian McArdle]

concrete....

You've sold me. That durabase solves so many problems it hurts. Have you asked for prices?

Christian.

[serrac]

Hi Christian,

I'm not sure if it's a good idea to quote the prices I've received from Durabase since they are specific to my requirements.

I will say that they appear competitive with having a concrete base excavated, filled and built up by builders. So may be rather more expensive than a DIY concrete base in a location with easy access and not requiring special equipment(i.e. not your garden ;-).

However, given the advantages in your particular situation and the speed of construction this system affords as opposed to a concrete found it looks like a no brainer to me.

Contact Elwyn Roberts [e-mail] at Durabase for a quote tailored to your requirements. He responded to my query in less than 24hrs.

Regards

Serrac