Compressive strength for stone wall built with lime motar

[Sloan36]

I have an old granite stone block (600mmx600mmx300mm)wall built with lime motar. The wall is an external wall of an existing house and it is proposed to extend the property. A steel 203UC46 supports the 1st floor slabs and bears onto the existing stone wall. The ultimate reaction of the steel is 110kN. Building control have asked for a steel post to be inserted into the wall or caluclations to justify the wall capacity. I think it will ok but need calcs to prove it.

From BS5628-1 I require a characteristic compressive strength for natural stone built using lime motar

Does anyone know what Characteristic strength I should be using?Any input would be much muched welcomedSloan

 

[ishvaaag]

See attachment for decades old references. The given stresses are limits to the factored load combinations.