How to repair footing bricks that have been chopped off!

[Patient Zero]

Hello!

Around 10+ years ago the previous owners of our 120 year old Victorian house had planned to convert the cellar into a extended basement, they had plans drawn up, a planning application put together, a number of quotes and even had dug 5 trial pits in the cellar - they decided not to proceed for whatever reason.

The cellar is around 4.5 x 6 meters with around 1.75m of headroom. The floor is a slab which looks like it's been down 30 years +.

Fast forward 10 years and I am filling in the pits properly (they had filled them with broken tiles...) - on one of the pits dug against an external wall I am concerned to see that not only are the footings exposed but in a section of the wall (just under a meter wide) somebody has cut off the footing bricks and taken a few out for good measure..!

You can see the pit against the wall here (I'm also in the process of cleaning the brick wall as you can see)

Cellar_zoom_out

• Patient Zero
• 21 Nov 2018

Looking closer you can see one of the footing bricks left intact (to the right) - note also some ground water from recent rains.

Cellar

• Patient Zero
• 21 Nov 2018

And close up, the full horror... the external wall is to the left of the picture

Cellar_close_up

• Patient Zero
• 21 Nov 2018

I don't want to just backfill the hole with london clay, I'd like to make good as best I can the damage done to the footings.

What I was thinking is to very carefully clean up the hole being careful to to move any undisturbed ground. Then fill with concrete up to the level of the first brick but use a form so that the concrete does not extend past the end of that remaining footing brick. Then to use a lime mortar to repoint the remaining but cut footing bricks and then fill in the gaps where bricks have been removed also with lime mortar.

Does that sound reasonable?

I wasn't sure whether I should concrete up to the brick or to just below it (say 50mm under) and dry pack the gap.

I originally thought about using a lime concrete (NHL5 + aggregate & sand) - partly because the bottom of the footings does have ground water sometimes (when it rains more than a little bit).

 

[bobasd]

what do you want to do with the cellar?

 

[Patient Zero]

what do you want to do with the cellar?

Probably just clean it up, perhaps lay a new slab and use it as storage, for now anyway. Next door (same building) have done a full width basement conversion and dropped the floor a couple of feet, tanked it etc.

Maybe sometime in the future we may do that but for now I just need the cellar "sound".

cheers

 

[bobasd]

you'l never have a sound cellar unless you tank the walls and install floor gutters, a sump an a sump pump.

to "clean it up"dig out the floor to whatever depth you want but stop if water comes into the digging - then lay a DPM that comes up the walls above the proposed finished floor height.
then lay insulation and then pour your slab to known an marked benchmark height.

the disturbed footings - remove all the dodgy an missing brickwork an replace with new bricks.
use 3:1 sand and cement mortar with full beds and perps.

the walls would be best left bare or rendered with two coats of 10mm 3: 1 lime render.
the render will only last a few years before having to be re-done.

 

[Patient Zero]

thanks bobasd, with the footings I guess that will mean removing a dozen or so of the cut footing bricks and then replacing with new. What would you recommend for bedding them on? You can see in the photo that the existing bottom course of the footings bricks appear to be on crushed red brick (that's what it looks like to me) .

On the walls, I'm working on stripping them back to just the brick work - mostly to help them breath a little. Currently mostly covered in paint and/or severe salt/mineral build up.

The footings are my current priority though.

cheers

 

[tony1851]

You're worrying needlessly. The wall above will 'arch over' the gap, and the clay will be sufficient to take the slight increase in load either side.