Which size rebar for garage trench foundation?

[f0rmula]

Anyone know which rebar I'd need for the footing of a trench foundation? The footing is going to be 450mm wide, 350mm deep (deeper than I'd like, but a long story). There are quite a diameters available.

http://www.buildingmaterials.co.uk/high-tensile-rebar.html?filter=&fl5=Rebar

Also, how many runs of it? Do I want two runs near the bottom (or even the middle?):

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Or three runs, with one nearer the top?:

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Or even four? Four is starting to get expensive though. It's only a blockwork garage

Thanks for any opinions!

 

[jeds]

Why do you think you need rebars in the foundation?

 

[f0rmula]

Because there was rebar in the footing I removed. And there are a lot of trench footings on google images with rebar in. It seems like a sensible place to put it

I assumed that was the norm. Is that not the case?

 

[jeds]

I've been designing, specifying and building extensions, garages, houses etc. for about 20 years. I have never put rebar into a standard strip foundation - nor seen anybody else do it. Ring beams for piled foundations - yes. Reinforced rafts - yes. But not in a standard strip. If the ground is suitable for building on you don't need rebar. If it's not, you need a properly designed foundation.

 

[f0rmula]

Right. Well, thanks for that That's saved me quite a bit of money

I saw pictures like this:
http://www.schlatter.org/images/New house/Footers/rebar in trench.JPG

... and what with the previous footing containing rebar, I just assumed.

Looking back at the images on google a lot of them do seem to be the edges of reinforced slabs.

Thanks for the quick reply

 

[DanDIY]

That website is American. They probably do it differently.

If you are going to follow stuff from the net, then I'd at least make sure that it is applicable to the country you are in!