Excavating 1.2mm down, 4.3m from house to accommodate storage shed

[frusc]

I have a small garden (rest was sold off before I bought the property) which is 8m x 8m. It is also several feet below the ground floor of the property (there's a 1m high basement underneath the house), with a slope falling away to the rear of the garden. I got planning to raise the entire garden to ground floor level with decking, and a 3.5m x 7.5m storage shed to the rear underneath.

Having stripped away the old decking I now know the exact levels and to accommodate 2m interior height, we'd need to excavate up to 1.2m (including foundations).

The edge closest to the house (4.3m distance) would go down 0.8m, plus 0.4m for foundations for retaining wall. The opposite side (3.5m further down the garden which is lower) would go down 0.4m plus 0.4m for foundations for retaining wall).

I thought I'd check if this is reasonable in principle, before spending any money getting it checked formally. As if its not I may just give up on the shed being standing height.

Also between the location of the new shed and house (4.3m area) there is an existing cement slab (approx 0.14m in depth), I assume this was a patio area prior to the gardens being split.

I know I'm outside the 3m rule. I also think I'm well outside the 45deg rule (as I understand it) thanks to our friend Pythagoras.

I don't want to head down this road and spend time/money only to be told its a silly idea. Hence the question.

 

[frusc]

I thought perhaps a sketch might help as my description is a little confusing having read it back. The area with artificial grass is where the shed will be. The planters behind that are the rear boundary. The large area of decking is the 4.3m between the house and the shed.

 

[frusc]

I thought perhaps a sketch might help as my description is a little confusing having read it back. The area with artificial grass is where the shed will be. The planters behind that are the rear boundary. The large area of decking is the 4.3m between the house and the shed.

 

[frusc]

For the benefit of anyone else in a similar position, my architect popped by this morning and confirmed it should be fine given its well outside the 45 deg line. Also he recalled from previous work we'd probably hit hardcore and the house foundations are likely deeper then the excavation since the ground slopes away for quite some distance.