Foundations and Rebars (reinforced Bars)

[Austtheboss]

Good day to you all! I am working on a Office in my garden and I wondered if anyone can help. It will have one pitched roof with highest point at the back down to the front of the doorway (it is this way for my solar panels to catch the sun!). The back wall will be 15 blocks (not bricks) high and the front will be 12 block high giving me a rough angle of 10 degree roof angle (min I am allowed for the roof I have chosen)

The ground is pretty good with no clay. There are trees and all will be removed along with roots b4 I start!

This Build is double skinned with 100mm cavity ssssssooooo my big question is 'in my foundations I am wondering if i should use rebars or not!'

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Please help!

 

[RedHerring]

Been discussed very recently. see here
http://www.diynot.com/forums/viewtopic.php?t=209080

 

[Deluks]

Assuming the ground isn't clay, crappy, surrounded by trees, near to any other structure etc etc You 'd do better digging down 1M, 450mm wide and 300 deep.
or something.

 

[jeds]

Re-bar or mesh is unnecessary in a normal strip foundation. The critical thing is ground conditions and sufficient depth to avoid frost damage.

From what you say a 750 deep trench with 225 thick concrete should be sufficient but it does depend on ground conditions.

 

[Austtheboss]

Hi Jon thanx for the post but it's not 750 deep it's only 300deep and 800 wide. Do I still not need bars?

 

[noseall]

Hi Jon thanx for the post but it's not 750 deep it's only 300deep

Dig it deeper and narrower then!

 

[Deluks]

Hi Jon thanx for the post but it's not 750 deep it's only 300deep

Dig it deeper and narrower then!

Hmmmmm!

Where did you get the 300/800 idea from?

Also be aware that removing trees could create just as many problems as leaving them in. It's not a get-around.

 

[jeds]

800w x 300d might work as a designed foundation but it would need to be properly designed. You can't just throw re-bar in any old how.

the question is, as already pointed out, why? (the odd shaped foundation that is)

Just as a general rule - take a line at 45° off the bottom of the wall and that line should not pass through the bottom of the concrete strip. The purpose of this rule is to keep the strip from being too wide which would create too great a moment on the centre of the concrete and most likely cause it to crack.