Boxing out Overhang

[magnethead]

Hi There,

I need an overhang to drop a Further 300mm from where the poured floor will be.  What way would you recommend boxing it out?  I got some advise from the builder doing the ICF at the moment to just get some 150mm foam insulation sheets and screw it up to the Floor/concrete above, Does this sound like the way to go, given it's only 300mm.

My under side on this overhang will be left at 3M (With concrete beams just inside it's edge - see below)) by the builder and it needs to be at 2.7M

 

Thanks

 

 

 

 

 

 

 

 

[magnethead]

I was just thinking, maybe  a 30cm box of  insulation hanging below this overhang, would not be structural enough, and might move and crack the render over time?  Would you drop some Steel legs off the concrete beams above?

 

 

[andyscotland]

I would think the insulation would shrink a bit over time, yes. What's the render on above? I'd think it would be good to make whatever that is continue vertically down to the bottom of the box. You could still fill the void with insulation but probably want a single flat surface to render onto

[magnethead]

Hi, Yes, the 3D shot looks a bit weird above, the Idea is to box it out seamlessly, all in the same render, underneath and on the sides...I literally want to extend the overhang downwards,

So insulation shrinks over time, I didn't know that, I guess so does wood, so would little metal legs be the way to go then?

 

Thanks

[andyscotland]

Well metal grows and shrinks over time (due to temperature). All materials move, hence I think the key thing is that the legs/framing of the "wall" sections of the overhang should ideally be the same as and continuous with the actual wall above and beside the overhang.

 

E.g. if they're a render carrier board on metal/timber battens then that system should extend across the face of the overhang too.

[magnethead]

oh right, I have you, It's all insulation above (ICF blocks) ...so 100mm insulation facing all the way up with a render covering eventually, the upper floor is being built currently.. I arrange to go that way. Thanks