Retaining Wall - Basement conversion

[Simz]

Hello,

Im looking for a bit of advice regarding a project im looking to complete. I have just submitted the planning documents for a remodelling of a semidetached Victorian property. I am intending to turn the existing full height basement into a 2 bed flat. The access to the new flat will be towards the back of the property on the side elevation.
Im currently putting together a groundworks package to talk to suitable contractors about. Within this package will be forming the new entrance to the flat by a reduce dig approximately 1m deep, 5m long and 3m wide. One side of this excavation will be tight up to the properties boundary, and existing boundary fence. Im aware there is a current rule of thumb which looks to have the width of a retaining wall ½ the height of the wall, however im struggling to find a specification for retaining walls. Also, Im restricted to how far I can excavate to the current boundary line.

Any advice or guidance appreciated.

 

[Static]

Garden retaining walls as a very rough rule can be 1/2 height on bases. But when your talking about proper walls that dont fall over every 10 years youll need a designed wall.. the base width will depend on material, shape and load on the wall..

You can excavate pretty much right upto the boundary line, so long as you support the adjoining owners land and any buildings they have within the zone of influence

 

[Simz]

Thanks Static,

so it seems i will need a formal design for this from a structural engineer, as apposed to a builders design?

 

[Static]

If this is an external "ramp" thats not in any way tied into the main building then maybe you could get away with a "builders design".. but chances are building control will ask for calcs if your anywhere near the house so you might save yourself a headache by getting a proper design done..