Orangery footing for timber frame extension

[Mickbodie]

Good morning just looking for a little advice on a footing make up for a small timber frame orangery. It’s 3mx4.5m. Currently been advised a footing 500mmx500mm will be adequate? Thoughts please 

[markc]

500x500 is a substantial footing, but the footing design depends on how the structure is fixed (or not) to the existing as you don’t want differential movement in the event of ground shrinkage or heave.

[Mickbodie]

Hi the timber frame will be Chem fixed to existing wall will probably make hole slightly bigger as the movement should be negligible on a single storey building 

[Mr Punter]

My brother had an orangery added to his house.  Original house built on deep plies.  Orangery on a raft.  Clay soil.  After a fairly short time the orangery doors seized.  It has now been demolished as it risked causing structural damage to the house.

[Mickbodie]

8 hours ago, markc said:

500x500 is a substantial footing, but the footing design depends on how the structure is fixed (or not) to the existing as you don’t want differential movement in the event of ground shrinkage or heave.

 

[Mickbodie]

What was the rafts build up?? 

[markc]

9 hours ago, Mickbodie said:

Hi the timber frame will be Chem fixed to existing wall will probably make hole slightly bigger as the movement should be negligible on a single storey building 

As it’s fixed to the building, do you know the depth of the existing footings? Ideally the new structure should be footed at the same depth. 

[Mickbodie]

It’s a new build house, block and beam.