Joining foundations - Joining foundations or removing the orig

[beninbrum]

I was having a raised patio put up, and in four months all that has happening is foundations went in, and one course of bricks at the front. So I have been looking at the work done when I realised that the foundations have not been laid so the wall will line up with the existing house wall. On the picture you can see the inner line I set out is the projection from the wall and the outer line is 1 brick width past that; as I understand it that is where the foundations should be finishing.


I have dug a trench to get the foundations in the correct place. However I am wondering if I should remove the original foundations first, or if the new concrete will make a good enough bind to the old one. Any advice?

[rxbren]

The line you have pulled doesn't look right you need to have the line at least a metre back down the side of the house to be able to pull a straight line to match the existing wall.
I'd personally start afresh and rip the old concrete out as a thin strip at the side wont be good enough

[GB_Groundworks]

Your brick wants at least another 350-400mm to the right as looking from the camera, use a straight piece of timber etc if your not good with string lines.

As for joining foundations they should be drilled and dowled with rebar every 600mm ideally but for a patio pouring next to them should be ok assuming good ground

[beninbrum]

Thanks for the replies. I'll remove it. Everything I have read about dowel is about putting them in before concrete is poured. I have seen come pictures of retro fitting to concrete roads in the US, and I expect I need to follow more of that approach. So I would drill a whole much larger than the dowel in the old concrete and then when the pour happens ensure that the new concreate is well packed into that hole containing the pin. Is that right?

I was using a "ping the line" test against the wall and I take the points of (a) using a longer line down the wall for accuracy and (b) checking that with some long bits of wood of other straight edge.

[GB_Groundworks]

you drill and use epoxy resin to fix bonding dowels, sometimes in certain engineer defined joints you will have sleeved dowels that allow for movement but not in this case