Cavity Gap between new and old slab

[Galgt4]

Two questions, 

 

building single storey extension. Original inner slab is on block & beam and new outer is mesh slab (footings piled)

 

1. We have two engineering solid brick pillars to build for steel to sit on top. Took out both skins to build pillars and there is a cavity about 2ft deep. See image. Can we just shutter and concrete this void then lay dpm and build pillars on top? 
 

2. What do we do with the rest of the cavity between original slab and new slab when knock through is complete to join both floors?

[Russell griffiths]

I would say if it a footing to take a pier to take that steel which is holding the entire back of the house up, then the foundation should have a proper design by a structural designer, then the foundation same as the pier. 
 

this is not an area to be guessing or scrimping. 
 

@Gus Potter

[Galgt4]

5 minutes ago, Russell griffiths said:

I would say if it a footing to take a pier to take that steel which is holding the entire back of the house up, then the foundation should have a proper design by a structural designer, then the foundation same as the pier. 
 

this is not an area to be guessing or scrimping. 
 

@Gus Potter

Hi mate, 

BC said he’s happy for the pillars to be built up off the block from floor/top of slab level and only seemed bothered about insulating that section. This is why I’m questioning it. SE engineer just says make sure foundations ok with building control??  It’s built up with block from foundation to dpc then engineering brick. See image.  

[saveasteading]

It's not for us to say. It is a project specific thing, so your SE should advise on the structure, not the BCO.

The BC can advise on insulation and damp, not that they should be designing for you.

 

But as an overview, and as @Russell griffiths  .. that is a big beam with a big load and the footing is absolutely NOT designed to support it.

[Gus Potter]

4 hours ago, Galgt4 said:

building single storey extension. Original inner slab is on block & beam and new outer is mesh slab (footings piled)

Hiya.

 

A few observations. 

 

Your temporary propping looks potentially dangerous. There is no bracing to the props and the needles appear to be not able to carry the roof load, never mind any internal floor load. It may be the way the photo is taken, but please, contact your SE tomorrow or NOW, DO NOT believe your BUILDER or BC!

 

Your gable wall is not braced so any shift in the temporary load could shove the gable wall out (all it needs is 25 - 50 mm) and that leads to an excessive / uncontrolled collapse. 

 

From the photos I see this look dangerous. 

 

The prop and the needle on the right side of your photo will be carrying a lot of load as the lintel over the first floor window will be shedding load towards it. 

 

Seriously,  please get your SE out to the job as this could be massivley unsafe! BC are NOT Structral Engineers and often won't understand (justifiably) the nuances. 

 

You are potentially taking your life and family in your hands here! I don't make such comment lightly. 

 

Get your SE to not just check the temporary works but also the building sideways stability in terms of what you are building. 

4 hours ago, Galgt4 said:

SE engineer just says make sure foundations ok with building control??

Are you sure this is what the SE is telling you and do they know, what you are actually doing on site, and if you have deviated from their design in any way?

 

Please take my advise. Any SE is going to help out here if there is a safety issue. 

 

Edited 1 hour ago by Gus Potter