Eccentric Party Wall

[Contraflexure74]

Hi All,

I have a scenario where a 2 storey house extension edge wall sits eccentrically on a strip footing (outer edge of strip). I have gravels at 500mm down from formation and my geotech says the design bearing capacity of the gravels is 175kN/m2. The strip fails in bearing due to the block wall load. He says the ground above the gravels is fill and is not suitable for a ground bearing slab on ground floor and recommends suspending it. If I pour a lean mix on the gravels and raise the strip and tie the suspended slab into the strip footing will the slab help solve my bearing failure problem, ie will the slab counteract the eccentric effects on the strip leading to bearing failure? Or will the suspended slab worsen the bearing effects on the gravels? Any ideas welcome.

Thanks.

 

[hokie66]

See JAE's suggestion in this thread.

thread507-443727

 

[raligt]

Can you not pour a new foundation directly adjacent of the same thickness and bearing strata as the existing and use steel dowels at say 300mm centres? We have done this many times for new extensions. We have also used new to existing foundation overlaps in the past also.

Using a suspended slab would be most preferable in this scenario though instead of ground bearing.

 

[Contraflexure74]

Thanks hokie66, very clever detail but expensive I would say.

I'm not with you raigt, are you suggesting dowelling our strip footing into the existing and sitting our wall on the neighbours footing?

 

[raligt]

Sorry CF74 did not realise it would be sitting on a neighbours footing. I would only do this if the foundation was owned by the same client.