Concrete

C

Craig Graham 22 years ago

I'm back to thinking about my concrete shed base, mentioned briefly a couple of months back.

Wife does not believe I can do simple maths and insists I get the opinion of "someone who knows what they're doing." Even though I've done this from scratch three times so far on different occasions to try and convince her. Hopefully enough people here will fit that description.

I'm basing calculations initially on 3m by 3m at 10cm deep, although I'll make the base a bit bigger than that to give a margin of error for the 3m by

3m shed that's going on it.

3 x 3 x 0.1 gives a volume of about a cubic metre. I can get that delivered for £118 ready to place by Minimix.

Alternatively, you can buy bags of ready mixed concrete to which you just add water. Ronascreed quote 90 of their 28kg bags per cubic metre, and at an optimistic cost of a fiver per bag that gives a materials cost of around £450, plus delivery since it would otherwise be a pain in the backside making multiple journeys in the car. And then of course it all needs to be mixed.

A previous poster on here suggested getting the ballast and cement seperately, but again using bags. That worked out cheaper than the ready-mix bags but not as cheap as the ready-to-place bulk delivery.

Can someone confirm that the figures are OK and that having the cement mixer come and deliver is indeed the best option?

-- Dr. Craig Graham, Software Engineer Advanced Analysis and Integration Limited, UK.

formatting link

Vote

J

John Woodhall 23 years ago

64 kg cement 120 kg sand 240 kg gravel 60 litres of water

Mix 4 gravel to 2 sand and 1 cement.

Don`t bother with the readymix its very pricey.

Its about 15 quid for the mixer for a days hire. IMHO its well worth it.

Vote

T

The Natural Philosopher 22 years ago

Sounds about right. I'd say you would need a ton of sharp sand, a ton of ballast and about 20 bags of cement. Unless you can get that lot at a discount, that's more than 100 quid.

Vote

T

tony sayer 22 years ago

In article , Craig Graham writes

You are not alone. I too have these silly bu**ers thing with her indoors too. Dunno quite why they do it, is it to make you appear stupid?, or so they don't feel so stoopid by arguing.

One thing apart from death and taxes in this life, is that despite luvvin 'em to bits I'll sure as sure is, I'll never ever understand the way the female mind works:!.

|Sounds like the correct decision and the simplest and easiest way of going about the whole thing!.

No not a good idea..

For that amount I reckon the redimix option is your best bet.

Yep, that's what I'd do and get the missus involved its nice to make 'em work takes their mind of worrying if you have your calc's right:)

Does she pop in at work to see if your code stacks up?..

Vote

M

Mike Dodd 22 years ago

I'm no expert, but having shifted 2.5 tonnes of the stuff, I have my own opinion...

Have a check on

formatting link

website for volumes/quantities, but I know I bought 2x1 tonne sand (£50) and 15 40kg sacks of cement (around £36) with free delivery - rather less cost than your pre-mixed and I think a rather larger volume. This did, however, require SWMBO to man (woman?) the cement mixer and break her back over a two day period, so you have to consider that, plus the added cost of the mixer, then there's the barrowing (and cost of barrow) involved in the mixing-it-yourself scenario.

Also, take care with what you think is ready-mix - a mate at work was laying a patio and bought a load of ready-mix bags, only to find a small bag of cement inside each bag of sand - so he still needed to mix by hand - at around 2-3 times the cost of my separate sand/cement.

TBH, if you can get a wet-mix delivered for £118+vat (if that is what minimix is) then for a simple base I'd personally snap their hand off and go with that. Probably a better mix, and a lot less effort for yourself. If in doubt, chat to a local builders merchant and see what they can offer - it's their bread-and-butter.

Regards.

Vote

O

Owain 22 years ago

Perhaps she could amuse herself in the kitchen making a nice cuppa for the delivery driver.

Owain

Vote

S

sid 22 years ago

">

Looking to do something similar but I have some spare 3x2 ft flags- round about 2" thick.

Going to prepare a thinner base than 4", maybe 2" and lay the flags on top. Certainly cheaper option as I already have the flags but second hand flags - old and ugly - should not be hard to find. Depends on sub grade and load bearing required for thickness of concrete. General advice is to have an overhang by making the concrete base smaller than the shed. Water does not collect around the base of the shed with consequent rot damage.

formatting link

calculator shows your volume at 0.9 cubic metre.Maybe worth while thinking of another project to take up any excess if you get a bulk delivery and you overestimate quantity.

Vote

R

Rick Dipper 22 years ago

One more thing to consider is getting the stuff from the road to the desired location. if the shoot on the mixer truck can reach, then

100%, else you will get 10-15 minuites to shift a cube, or pay "waiting time", a cube of concrete weighs in at over 2 tonnes. If you wait too long the mixer will likley dump you a pile of concrete that is almost set.

You can get these guys that come with a lorry of aggrigate and a mixer on the back, they mix and barrow it to the right place, you just lay it.

At my house, I get a convoy of dumpers in, as I can't get the concrete mixer within 1/2 a mile of the house. Its at this point that the bags and the cement mixer start to look cheep. For anything under a couple of cubes its the mix it myself approach.

Two more questions for the minimix guy are

1) retarders - slow down setting, but weeken the mix 2) fibres - reduce cracking

If its a hot day you will need to water the cement so that it sets before it dries, so a hose pipe also helps - yes I made a dash out for a hose.

For laying, its a wellies, jeans and gloves job, you get in the stuff and work from one end, concrete will burn you, so keep it off your skin.

Rick

Vote