Retaining concrete reinforced block wall

[Mickey11]

Huu I’m all I’m looking for a bit of advice. Looking to extend the patio on the back of my house but have a 6mt drop from patio floor to ground level. The ground is of clay very hard. I’ve upload some pictures of the patio now and a rough sketch of the new patio. I am open to suggestions and ideas. I was thinking of having it built out of hollow concrete blocks reinforce concrete and Rebar/ same for the footings. Thanks Mickey.

 

[XR250]

Probably a segmented wall is the only thing that is going to work

 

[Greenalleycat]

Looks like an expensive undertaking

I don't really understand the geometry of this (how big is the patio now vs extended?) etc but my suggestion is using a suspended deck over piles
Timber would be easiest but you could do it in concrete if you really wanted - have a few very deep / large diameter piles and stick steel posts with steel beams over, then timber or concrete floor as you prefer
Probably cross-bracing in the subfloor as the bracing rather than moment frames

 

[BridgeSmith]

Probably a segmented wall is the only thing that is going to work

You're referring to a block-faced MSE wall? If so, I agree that seems like the best option.

 

[Ron247]

Not sure what is new versus existing in your sketch. Why are you dropping 3m twice rather than 6m once? I see 2 walls that are 1 meter apart. Is the word "patio" new, or old patio? The pictures look like you already have a patio area.

Are you dropping to the level with 2 separate chairs in the picture or the level with the 2-seater?. You need to add some dimensions for the area uphill of the new walls. Also, the actual footings may be wider than you show.

Looks like you use the same version of AutoBad that I use, but draft sketches like that are supposed to be on the back of a cocktail napkin.

Have you had water issues with the existing walls? I see brick that has been reworked in some areas. The reworked area looks like it is near floor level.

 

[Mickey11]

Hi thanks for your reply. We have been in this house for about 7years and don’t know any history of the patio but looks like it was just thrown together. The only reason why I was asking is because we have noticed some movement over the past years and are now looking at putting a new retaining wall in. We don’t really want to be looking at a 6mt high x 7mt wide wall from the garden so was looking at a 2 tier walls to soften the look.
general rule of thumb is that the tiered walls be horizontally offset by a minimum distance of two times the exposed wall height of the lower wall. I don’t really want to be putting a 3x7 wall halfway down the garden so is there any way of supporting the second wall about a meter away from the 1st wall. Thanks

 

[Mickey11]

Hi thanks for your reply. We have been in this house for about 7years and don’t know any history of the patio but looks like it was just thrown together. The only reason why I was asking is because we have noticed some movement over the past years and are now looking at putting a new retaining wall in. View attachment 10983We don’t really want to be looking at a 6mt high x 7mt wide wall from the garden so was looking at a 2 tier walls to soften the look.
general rule of thumb is that the tiered walls be horizontally offset by a minimum distance of two times the exposed wall height of the lower wall. I don’t really want to be putting a 3x7 wall halfway down the garden so is there any way of supporting the second wall about a meter away from the 1st wall. Thanks

This is the plan to hide the 1st wall. 2nd wall will have planting.

 

[BridgeSmith]

general rule of thumb is that the tiered walls be horizontally offset by a minimum distance of two times the exposed wall height of the lower wall.

That's the typical limit where the loading/design is independent. They can be closer than that; they just need to be designed considering that they interact. A proper design can account for any distance between the walls. It may require more extensive excavation for some configurations.

 

[Ron247]

Are you going from the current patio level down to the level with the sidewalk and the 2-seater bench? If so, where are your stairs going to be and what kind of stair (spiral, 2 tier etc) are you intending to use?

 

[Mickey11]

Thanks bridge smith so maybe if possible interlocked the 2nd wall with the 1st wall.ie full slab of reinforced concrete and then built on top for 2nd wall. I know the 1st wall needs footings to be minimal of 1mtx1mt. With a key at the bottom.

 

[Mickey11]

Are you going from the current patio level down to the level with the sidewalk and the 2-seater bench? If so, where are your stairs going to be and what kind of stair (spiral, 2 tier etc) are you intending to use?

Patio is definitely moving so if I’m doing a new wall it will be coming out around a metre. Steps will remain where they are but will be new.