party fence wall underpinning question

[jimmy77]

Hi,

I share a 1.2m high Victorian double brick width garden wall with my next door neighbour. It is built on a foundation of flat rocks that are no wider than the wall itself and the soil beneath that is clay.
I would like to lower the levels along the wall in my garden so that I can build a shed. I want to build the shed at a lower level so that it doesn’t protrude above the fence on top of the wall, and generally look imposing.
To investigate, I dug out on my side to the level of the wall's foundation, but then worked out that this is not low enough for my shed base. Is there anything I can do to underpin the wall with concrete from my side only, that would then allow me to lower my levels below the original foundation level of the wall?

I've drawn up a diagram to show what I mean here...
http://i.imgur.com/DPKcI.png

Any help much appreciated.

Jim

 

[big-all]

heeelllooo and welcome jimmy77

you definitely cannot underpin half width as the grounds heaves the wall will rise and fall on one side causing it to crack and destabilize the wall
you could put a wall on your side off a suitable size to hold the ground underneath in place [ a retaining wall]

 

[^woody^]

I can't understand how or why you are going to build a shed 1m lower than the wall. It will be in some sort of hole in the ground won't it?

 

[jimmy77]

Hi - thanks for the replies - its sounding a bit depressing though.

I don't need the shed base to be 1m lower than the foundation of the wall - it's more like 150mm below the foundation.

This makes it clearer...
http://imgur.com/JWKaI

Space is tight in the garden. I'd like to build the shed frame anchored to the wall and use removable panels to allow access to fence panels for painting etc.

I'm concerned that my neighbour won't go for the design if I block out his daylight though the 300mm trellis at the top of the fence, hence wanting to keep the top of the shed below this line. The other constraint is the height of a person working / standing in the shed - I think I've paired the headroom down as low as I can.

Jim

 

[big-all]

sorry for the pictures again

perhaps a different approach
i am 5'11" I PLANNED MY SHED as low as possible with maximum room
you dont need head height at the sides if you never stand there

i have 6ft 3 head height inside my shed around 10-12 inches from the side the height off the sides is 6ft the total height is around 2.7m or 8ft 10"ish
the shed is 10ft wide plus gutters and overhang
i went to a great deal off effort to keep the height down and keep it looking pleasing and the neibours love it
http://s21.photobucket.com/albums/b270/bigall2005/

 

[^woody^]

I don't need the shed base to be 1m lower than the foundation of the wall - it's more like 150mm below the foundation.

Your existing wall is 1.2m high, you want your shed height lower than this - so that would seem to mean digging down at least 1m for a typical shed height

So it seems that the shed will sit in a hole, or you need to take a lot of ground away if its a long wall

Anyway, if you lower the ground on your side, then the wall becomes a retaining wall so underpinning may not be the best thing. However if this work just relates to a typical 2m or so shed length, then you could build a retaining wall up against the existing wall at a lower level

 

[jimmy77]

Hi Woody,

The existing wall is a little over 1 metre high, but it also has fence panels sitting on top of it and then trellis above those. See this sketch...

http://i.imgur.com/obb8x.png

I'm keen on exploring the retaining wall idea now. Given the dimensions of things in that sketch, would I be able to get a retaining wall built, that comes up to the same level of my neighbours' patio in single skin heavy concrete blocks with a concrete foundation - as shown below?

http://i.imgur.com/87YiD.png

edit: In summary: All I really want to do is to lower the level of my garden 150-200mm beneath the level of the existing party wall's foundation. The shed is a distraction.

@big-all: nice shed. like the long wood storage hatches.

Jim