Help with aggregate amounts please

[britishboy7]

I’m planning on laying a concrete base for 2 sheds in the garden, a total area of 17m2. Was planning a depth of 100mm of type 1 MOT, then 100mm of concrete. Can anyone help with how much type 1, ballast and how many 25kg bags of cement I’ll need?

I’ve tried 3 online calculators and getting nowhere (one said I need 13.4 tonnes of type 1 MOT!!!) what am I doing wrong..

 

[Notch7]

my guess is you need 3 1/2 to 4 bulk bags of type 1 and ballast

Id guess at about 24 bags of dust; 6 per bulk bag

you require 1.7 cubic metres MOT and concrete.

a bulk bag weighs around 750Kg to say 850kg however the volume of stuff you get rather depends on how wet it is. you should get more during dry weather, less in winter

 

[britishboy7]

Thanks Notch
Life saver.... had similar quantities suggested elsewhere too so that’s what I’ll be ordering

Last question, when I pour my 4” deep concrete base onto my compacted type 1, can I pour it in one go, or do 2 pours at approx 2” deep each time and let it dry first

 

[oioi727]

You must pour it all in one go

 

[britishboy7]

Thanks guys, and oioi727 only asked as neighbours build a raised concrete base for a shed and concreted it over the course of about 4 weekends (Confused me no end)

Last request for aggregate quantities for a small footing please:

10m x 400mm wide x 400mm deep type 1

10m x 400mm wide x 100mm deep concrete

 

[Charlie George]

Thanks guys, and oioi727 only asked as neighbours build a raised concrete base for a shed and concreted it over the course of about 4 weekends (Confused me no end)

Last request for aggregate quantities for a small footing please:

10m x 400mm wide x 400mm deep type 1

10m x 400mm wide x 100mm deep concrete

You concrete at bottom of trench and build up from there, not fill with mot and concrete on top,and 150mm deep.
1 tonne ballast 8 cement will do your footing@ 150mm depth.

 

[britishboy7]

Charlie so only 150mm deep foundation for a small retaining wall? On another of my posts in the ‘building’ forum was advised to go down 450mm?

Apologies but new to this (as you can tell)

 

[Charlie George]

No dig down 3/4/500mm depending on ground? then concrete bottom of trench 150mm min,you could make concrete deeper, then build wall from there to required height, no need to fill trench with mot,and concrete on top.

 

[oioi727]

Ideally you want to dig down until you get to firm ground.

Ensure the bottom of the trench is flat and level as possible.

Keep the concrete covered so it cures slower to achieve maximum strength

 

[Charlie George]

Looking at your other posts it may be a good idea to order an extra bag of ballast and a few bags of cement,better than running out,any left could be used on patio etc, a better idea would be to use barrowmix readymixed.