Pad Foundation under corner of House ?

[billm]

Hi, I've just started digging the foundations for a 3m x 6m pitch roof kitchen/diner extension and had the 1st visit by the Building Control officer. I'm going to be doing most of the work myself and as I'm not a builder I have to get people to explain things to me in simple language rather than just rattling off building jargon and expect me to understand what they mean !

As there will be a full width RSJ across what was the back wall of the 1930's semi, the BC officer asked if I will be putting in a Pad Foundation on each corner ? After explaining I haven't got a clue what one was she did explain it would mean digging under the corner of the house foundations by 900mm to install it. I have a Structural engineer doing the Calculations for the Steels etc which will be forwarded onto the BC office for approval when complete but as yet he hasn't finished them so I'm not sure what he will specify is needed.

So I am jumping the gun here. I hope the Structural Engineer will say it will not be needed but if a Pad Foundation is required under the corner of the house, can someone explain what is the easiest way for me to build one ? Yes I could get Yellow Pages and ask a builder to do it for me but as this is a self build I'd rather learn and do it myself.

Here is the corner of the house the BC officer was referring to. The bottom of the existing house foundations are approx 450mm below ground level and the strip foundations I have dug in this area which have been approved by the BCO are 700mm down from ground level to compacted sand and she will accept 225mm deep x 700m wide concrete strip footings

 

[^woody^]

It seems like you mean underpinning and not a pass foundation.

Your engineer should be telling you what additional foundation is required, and he should be designing it.

 

[billm]

Yes I think you're right the BCO meant underpinning although she called it a Pad foundation. I asked the SE and he will tell me what, if any, additional foundation supports are required when he does his report.

But as I said above I am jumping the gun here and just asking how you would go about underpinning that corner of the house so I can get my head round what I would need to do if the SE says it needs doing.

From what I can find on i*net, you dig under the existing house foundation to the same depth as the new strip footings and go back the required distance, lets say 900mm. Then shutter off completely the strip foundation and open up an narrow access hole at the side of the house through which to pour in the concrete leaving a 50mm gap at the top. Then after 24 hours and it has started to harden, fill in the 50m gap with concrete and compact it as much as possible ?

 

[Deleted 224857]

has the engineer not given you any drawings.I am having same done to my 1930's house.Removing corner of house and exactly in the same boat.Upload some pics and i can tell you what my builder has advised,if the scenario is same and the house layout is similar.