Urgent help - Concrete Slab

[millyme1]

Our kitchen floor extension sits on an old garage slab and 30sqm of the slab is outside. We are in the process of having impressed concrete layed on the outside part of the slab (3 inches thick of concrete)

I am really worried that if we remove outside slab in the future (in 10 years time) then this will crack inside kitchen extension floor. Any ideas?

 

[RedHerring2]

I'm not a builder and only have DIY experience, but what I'd do is to make the break now, before the new concrete is laid.
In other words, using a 230mm cutter, perhaps backed up with a breaker/chisel etc, separate the two parts of the slab.
It only needs to be a separation of a couple of inches wide. Just so that any work on the external slab in the future does not affect the internal part.

You say that you're 'in the process'. Does that mean that you're about to, or that you have started.

If you haven't started yet, the imprinted concrete guys will probably separate the slabs for you before they start.
But I'd use a different builder for the separation, just to make sure it's been done properly. Depends on how well you can trust the imprinting concrete contractor.

I'm surprised how you managed to have a building on a previous slab that is part internal & part external. but I guess that's another story.

I suggest you wait for confirmation or other suggestions from the more experienced guys on the forums, but put the imprinted concrete on hold until you're satisfied with what you're doing.

 

[Static]

Right so you want us to predict what will happen to your property in 10 years time based on some loose information about a garage slab..

Maybe try these guys: http://www.psychic-forum.com/forum/

Or provide us with photos, sketches, dimensions, construction makeup of new and old, planned removal of slab, slab reinforcement etc etc etc..

 

[RedHerring2]

Just so you know Millyme, Static is 'considered to be' the resident Structural Engineer on this site, I believe. I don't know his qualifications but I'd follow his advice.

 

[Static]

Just so you know Millyme, Static is 'considered to be' the resident Structural Engineer on this site, I believe. I don't know his qualifications but I'd follow his advice.

Maybe one of about 3-4 engineers who come here perhaps..

Either way till you know more about whats actually happening, wouldnt advice cutting the slab up.. could end up with all kinds of problems with damp proofing and shearing of the slab edge..