Extending a shed base

Martyn_H

Hello

I am extending a concrete shed base from 8'x6' to 10'x10', to a depth of 2", but with 4" around the edges. The depths were what a builder said would be adequate. This is for a summerhouse.

My questions are:

How many ready-mixed bags of aggregate will I need? (I don't mind sacrificing cost for convenience).

Do I need hardcore for such a shallow construction?

How long will it take to harden off?

Many thanks.

Martyn_H

Any advice welcome!

Imp

The design for a foundation depends upon two things.

1) what is underneath it
2) what is on top of it

Without this information, it is not possible to tell you if your specification is adequate.

Martyn_H

Hi Imp

If I understand you correctly, underneath it will be compacted heavy clay soil. Above will be a summerhouse on wooden bearers.

Martyn_H

Hmmmmmmmmm

Martyn_H

Moderator please delete thread due to lack of response.

diggerman123

martyn , the formulae for cubing concrete is length x width x depth. give me a few minutes and I will cube it for you

diggerman

diggerman123

this cubes up at 0.5cubic metres at a depth of 4 inches all over (100mm)

i would also recommend that you "tie in " to the existing concrete to prevent it parting from the new although as it is only a summerhouse base you may be ok

for consistency , i would get entire excavation ready and order concrete ready mixed from a local concrete plant (will cost about £100 including delivery)
you would need a C35 mix at 50 slump

if you want to mix it yourself it will probably cost you nearly as much and will be a lot harder work ! but you will need
1x 1 tonne bag 10mm ballast
10 x cement

mix to a ratio of 3 ballast to 1 cement for a strong mix

concrete should be allowed to cure for at least 3 days

hope this helps

diggerman

REMEMBER , CONCRETE CAN CAUSE SEVERE BURNS - ALWAYS WEAR PROTECTIVE CLOTHING AND DONT GET IT IN YOUR EYES