Footings

[catlad]

I am digging footings for the inlaws new 5mx5m flat roof extension. The footings will be approx 4 foot deep, there will be 3.6 m bifold doors leading into the garden and I am wondering if I need to dig quite so deep at this point as there will be virtually nothing above, I was thinking maybe 2 foot would suffice at this point or am I missing something?
Ultimately it will be the building inspector who has the last word but I thought I would ask the question as it could save me a bit of spade work!

 

[johnny2007]

I know people who build extensions with 150mm fundations on mud.
By that standard you're going well over the top.
Back to planet earth, what are the drawings specifying?
To be honest, it's easier to dig all at same depth imo.

 

[^woody^]

This is the same situation as a garage door, where three wall foundations are often stopped at the jambs.

 

[noseall]

I am digging footings for the inlaws new 5mx5m flat roof extension.

Hand digging?

 

[catlad]

Thanks for the replies
The drawings say 200mm concrete when hitting firm ground, which the building inspector has deemed to be about 4' since his visit and he wants the same depth all round.

 

[freddiemercurystwin]

You have to stick a footing in of some description, it's not really like a garage door, that scenario doesn't have a bit of wall underneath it to support the door threshold and cold bridging isn't an issue with a garage floor slab.

 

[Londoner2]

1.2m is fine for footings, it really depends on other factors like trees etc.

 

[oldbutnotdead]

Bifolds are big heavy things & any differential movement could cause problems- may be best in the long run to bite the bullet & do the full strip...