Wall Foundation near drain cover

[Shinogi]

Hi,

Could someone give me some advice please? i'm after building a single row, 100mm medium density block wall which will be just under a meter high and I need to lay a foundation. The problem is that I have a manhole cover close by and I'm not sure if I'm allowed to put a foundation near it.

Untitled

• Shinogi
• 25 Sep 2013
• 1

The strip foundation will be going in against the leanto wall, in the middle of the picture, towards where I was standing to take the picture but there is a manhole cover to the left near the green recycle bin (garden is a bit of a mess at the mo due to my shed build going on).

I'm not sure where the drain goes but presume it goes to the right under where I want to put the foundation. Am I allowed to lay concrete over the possible drain pipe? How deep for the foundation would I need to go for a 1m high, single 100mm block wall? I presume I won't be digging deep enough to interfere with it.

 

[noseall]

How deep is that chamber and what is in it?

Can you show us a piccy of the inside of the chamber please?

My guess is you will be ok. You will need to dig down to suitable ground. Lay concrete footing aboot 300mm wide and 150mm - 200mm thick.

If you do come across the drain, it may be possible to bridge it.

If the drain (sewer) is shared with the neighbour then you should seek permission from your water company.

 

[Shinogi]

That was the information I was after, thank you.

The drain, as far as I am aware, is shared with the neighbour so that puts a stop to that then if I need to ask permission.

I was thinking of going 600mm wide so I could go about 100mm deep. If they need to get to the drain, the wall can be knocked down and foundations dug up easier that way if needed as I could always rebuild the wall afterwards.

Regarding what's in the chamber, it's just soil for the majority but I haven't dug too far down yet as I plan to do it at the weekend and don't want to have a hole there for the kids to fall in etc..

Thank you for your reply, it's helped a lot. I may have to go the fence route then but would prefer the longer lasting wall.

 

[noseall]

You will need the concrete to be at a certain depth, not only to ensure the ground is adequately load bearing but also to ensure that very cold temps cannot influence the footings, i.e. frost heave.

 

[Shinogi]

Ok, thank you for that, I really appreciate your advice.

I'll have a dig down tomorrow and see what ground I have but the top of the garden came to clay at around 500mm deep. Also, my wife has just informed me that it is our drain and isn't shared with the neighbour so it seems I wouldn't have to ask permission.

May I ask, and I'll probably sound stupid, but how do I have a concrete floor at the base of the wall or do I have to build out of the ground with block and refill the gap on top of the foundation with soil or am I ok to bring the concrete to the top level with the existing floor?

 

[Shinogi]

I've started digging down to where I'm going to lay the foundation. I've hit clay at around 250mm. Am I right in thinking I should dig down to 300-350mm and follow the advice given above to have a 150-200mm foundation?

Untitled

• Shinogi
• 29 Sep 2013
• 1

Untitled

• Shinogi
• 29 Sep 2013
• 1