Footings for walling - Over or around drainage

[Aalindo]

I will be digging footings for a garden retaining wall. The wall will run N to S and i know in 4 places i will meet 4" underground plastic drainage (both foul water (to septic tank) and surface water.

I know it's probably a daft question, but what is standard practice; dig deeper and finish the footings below the pipes and lintel the brickwork over them, or pour the footings around the pipes, or something else entirely?

You're probably thinking that i should not be trusted with jobs like this, but thanks in advance anyway! We all have to start somewhere!

[lutonlagerlout]

well at least you are asking before you do it wrong!

normally its after the carnage the questions start

you need to lintel over the pipes and surround with 100mm of pea shingle,this allows for movement

how high is the wall going to be?

dont forget your weepholes

LLL

[Aalindo]

LLL,

Many thanks for the reply. I suspected you'd say the above, but just wanted to check.

The wall will be approx 4-5 courses above ground. It will be 9" rather than single brick. I have not dug down yet to see how far below ground the pipes are yet, but there will probably end up being a few courses above the pipes, but below finished ground level, as well.

Weepholes are planned, but i will leave the specifics until closer to the time.

For now though, back to the porch project...!

[GB_Groundworks]

Or if you do include it in the footing it needs to be wrapped in expansion material and have a movement collar each side of the footing.

But if it's only a littke footing and the pipes aren't that deep go under them,

How wide are you making it?

[Aalindo]

Giles,

Many thanks for the reply. Can you confirm what you mean by 'movement collar'? A quick google didn't bring anything obvious up.

Planning for the footings to be 450mm wide in order to give some room to manoeuvre when laying blocks/bricks below ground level. I reckon they'll only need to be 300mm or so deep for 4-5 courses above ground.

[GB_Groundworks]

normally you cut the pipe 300-450mm away from the footing each side and insert a rubber flexible coupling one each side the footing to allow for movement

[Aalindo]

Ah, understood. I'll look into it. It's nice to have options. Thanks.

[seanandruby]

Not to confuse you but going through any structure you would need to be minimum 150 either side of the beam, lintel etc: and a minimum 600 rocker pipe on each side for movement.
Also you need to seal around the stub pipe to stop vermin entering and nesting under any structure you may have.