Concrete Pads for Steel Goalposts

[Simonharry]

Hi All,

 

I’m new here and was hoping you could help.

 

We are adding a wraparound extension to our 1930’s semi and the structural engineer has spec’d “goalpost” steels across the back of the original rear wall, supported at 3 points by UC steels on concrete pads.

 

Two of the pads will be under the existing suspended timber floor and will require “pits” to be dug however one of them will be effectively on top of / in line with the new foundations.

 

The pad required is 700Lx700Wx300Deep and the foundation is 600wide x 450deep.

 

My question is how do I create the required pad? Do I simply widen the foundation at that point to the 700x700 dimension and utilise the additional depth of the foundation?

 

The steel will be below ground level if I do the above once backfilled and concrete goes down for floors so my next question is……How do I protect the steelwork that’s below ground level from rust, degradation over time?

 

Hope the above is clear but happy to elaborate further if needed.

 

Thanks

Simon

Edited February 13 by Simonharry

[Russell griffiths]

Do you not have a foundation plan 

I wouldn’t expect the post to go down to the foundation , but instead sit on some concrete blockwork that brings it up to around dpc level or floor level. 
this lifts it out of the wet damp zone. 
 

concrete wise I would just widen your strip footing in the area of the post. 

[Canski]

They usually do go down to the foundation and are painted with RIW up to DPC level. In this case the foundation will need extending to accommodate the new steelwork. I recently worked on a renovation and they had about 6 of these.

[saveasteading]

It's easier to do as @Russell griffiths suggests. Concrete to a flat surface then drill and use epoxy and stud bolts.

But ask your SE: there are complex loads on a goal post.

It's worth painting the lower levels of the steel, using specialist paint or bitumen.  Any steel encased in concrete won't need paint.

[Simonharry]

Is it feasible to sit the column in line with the inner block work of the cavity wall to avoid it creating a large pillar in what will be the kitchen cabinet wall?

 

how will the dpc/cavity tray work if so as there will be a gap in that inner skin where the steel sits.

 

Thanks for the responses so far.  

[Mr Punter]

Yes you can have it in the cavity but it will be a cold bridge.  Best to have a bit of insulation around it.  You will paint the bottom metre or so with bitumen paint.  No issue with DPC.  If you have a cavity tray running around the wall you will need to stop it either side of the steel.

[Russell griffiths]

What is going on the inner wall, insulated plasterboard, or just dot n dab boards. 
if you are having a lot of wall units you might want to fit something to the wall to fix the units to. 
whatever you do I’m sure you can pad the surface out enough to fly over the face of the steel to hide it. 
 

or talk to the engineer and see what you can do to change the size of the post.