Cubic Feet and Cubic Meter

[ByronBlack]

I think im getting confused how to work out cubic feet and meters, and was wondering if someone would be kind enough to check my calculations.

I want to make 4 concrete plinths as the foundation of my shed, they are measured 10 foot long, 3 inches wide, and 6 inches high.

So my cubic feet for all four would be:

10 x 0.25 x 0.5 and then x4 for all the plinths
I come out with a figure of 5cu feet

If I then convert that into cu Meter I get the figure 0.15 (after rounding)

Does that sound about right? Im working this out so I know how much concrete to order..

 

[orangetlh]

sounds spot on to me, i dont know wether you need to add a certain amount of wastage to that 5 cube though as its dead on.

 

[cutting42]

Hi ByronBlack

Bang on the nail with the conversions, try this site, pretty cool.

http://www.onlineconversion.com/

 

[uwelin]

ByronBlack,

or try simply Google:
http://www.google.de/search?client=...r&sourceid=opera&ie=utf-8&oe=utf-8&lr=lang_de

Cheers

Uwe

 

[ByronBlack]

Cheers guys - nice to know I can rely on you lot to double check

Anyone know of a guideline price for ready-mix concrete? I'm going to ring round, but wanted a general idea before I call them - is there a way to roughly work it out?

 

[jasonB]

Readymix lorries carry 6 cu meters, if you don't have a full lorry you pay a surcharge for the extra space. 0.15 m2 wouldn't even wet the drum :!:

Even if you used "mixa-mate" type mixers they usually have a minimum charge of 0.5 cu mts.

You are only looking at 10 bags (40kg) of balast and about three of cement (25kg) so it can be mixed quite quickly by hand.

Actually just thinking about it you may be better off buying concrete lintels instead of going to the bother of making formwork, buying rebar and casting the plinths, just bead them on a bit of dry mix concrete.

Jason

 

[Johnboy]

Bit confused Byron, I thought your workshop was going to be 16 x 10 not 10 x 10? The 3" width sound very narrow to me, I would make them 6" x 6". Still too small an amount for ready mix but if you don't want to mix by hand it is cheap to hire a mixer for the day.

John

 

[ByronBlack]

Jason - some great advice there thanks. I'm so grateful to have knowledgable guys on here to point me in the right direction. I didn't even think of lintels - that would save so much time and effort! I'll have to look into that and source a supplier

If I decide to mix my own (if the lintels are too expensive) is there a formula on working how much sand, balast cement and water is needed to create a specifc cubic amount?

Johnboy - thats for the headsup regarding the widths, I wasn't entirely sure on how wide to make it, i'll re-calculate for the 6x6!

 

[OLD]

wall width should be same as studding to get most room and overlap cladding, no steel required its a light building on a proved base, bend threaded rods 90 degree at end so it locks to concrete

 

[jasonB]

Byron

There are 1.6tonnes of balast to a cubic meter, so depending on the bag size:

40No 40kg bags = 1 m3 - 6.0bags = 0.15m3
64No 25kg bags = 1m3 - 9.6 bags = 0.15m3 say 10 bags

Typical mix ratio will be 1:6 cement:balast to make it easy say 2No 25kg bags of cement.

You will need 12-14lts of water per bag of cenemt but this can be varied to suit the conditions a wetter mix will flow into your formwork eaier than a thick dry one. However too much water will weaken the mix.

You should also put som rebar into your plinths to help stop them snapping

Jason

 

[ByronBlack]

Thanks for all the info Jason - much appreciated.

I found out today that Wickes do a bag of general use concrete all pre-mixed, just ready to add water, do you have any knowledge/experience of this, and do you think it would be ok to make the plinths?

 

[jasonB]

For the small amount you need they will be OK although a little more expencive than balast and cement.

Jason

 

[PowerTool]

I've used them a few times for small jobs - the cement is in a seperate bag inside the main one.Easy enough to mix/use (I normally mix them in the wheelbarrow),but a bagful doesn't seem to go very far.

Andrew

 

[ByronBlack]

Andrew, thanks for the feedback. I've worked out i'll need about 13 bags, at £2.95 each, so its cheaper than I originally thought.

 

[RogerS]

Is that for your 3"x6" spec? Really do think you need 6"x6" as previously suggested...plus put in rebar (aka lenghts steel bar) as reinforcing..again as previously suggested.

Guarantee 3x6" will crack...unless going onto an existing solid base