Retaining wall for concrete slab

[kitsee]

Hi all, this is my first post on this forum and i'm hoping you guys can provide me with some advice with a project i'm currently undergoing.

The basic goal of the project is to create a level concrete platform for light uses such as parking for a trailer and storage area for waste bins. i'm currently demolishing a brick and cinder block shed that stood where i wish the platform to be. As can be seen in the image below, all but one wall is down and the foundations are all that's left.

some extra images with measurements are included in this album: http://imgur.com/a/RQtxy

my current plan is to extend the both layers of the foundation wall across to the building on the left, building the wall directly on the concrete path while also increasing the wall height by two layers. this area would then be filled with hardcore from the rubble then topped with mot type 1, compacted and finally concrete poured on top.

i'm now having concerns that the wall built directly on the path wont be strong enough to withstand the pressure of the hardcore.

I would appreciate any suggestions, thank you.

 

[Newboy]

1) Don't pour concrete against your (house?) wall.
2) It's probably a bit late but never demolish individual walls, demolish in layers from the top down - that way the remaining structure is less likely to topple down with you under it.

 

[kitsee]

Its a garage and its foundation is also concrete. the walls of the shed were built absolutely solid as a result i'm actually having problems getting the last wall to fall plus due to the confined space it would have be difficult to bring it down in layers.

 

[kitsee]

whats the problem with pouring against the existing concrete?

 

[Newboy]

You will probably bridge the damp proof course (if there is one) which might well be the start of a few other problems. Raising the external ground level against the side of the building is usually a no-no

 

[kitsee]

I very much doubt it has one, its a very simple structure. I'm not absolutely sure but i believe its a solid concrete foundation up to the level of the door then the wall above that is cinder blocks, the internal walls are bare. if it did have a damp proof course i would imagine it be put in at the level of the door so i'm gonna go with the risk on that one however if you do have an alternative solution i'm happy to hear it, other than that do you have any advice about the retaining wall i'm concerned with.

 

[theprinceofdarkness]

I am unhappy about a, bridging the damp course and b, rainwater that might pool on your plinth soaking the wall. I would build a rough old wall with your recovered blocks about 6 " away from the house wall. Go over your demolition site with a garden rake and recover bits of block/mortar bigger then a match box and fill the gap up to "2 of FFL. At the end, build new new retaining wall with a vertical mortar course inline with the rough wall and a bleed hole under it. Lay a couple of sheets of newspaper/cardboard/DPC over your gap, pour your concrete over the lot. Now if there is some problem, the bit next to the wall can be broken out in an hour or so for further work.
Frank
P.S have you tried to use a 8mm masonry drill on the mortar courses? Should make removing the blocks a lot easier.

 

[kitsee]

I just want to reiterate, the building is not a house, its a completely unsealed garage. The internal walls are bare cinder blocks with no plaster so is damp really that much of a concern in this case? sorry if there is something simple I'm missing

 

[theprinceofdarkness]

Depends what you want to put in it, it would be a shame if the quantity of water going through the wall would cause a puddle inside. Hence my suggestion of a bleed hole for the section next to the wall.
Frank