In over 40 years working with concrete, I've NEVER seen a spec requiring lust 25mm cover to steel. That spec drawing looks like a standard detail that has slipped through proper checking and, because far too many specifiers/architects now spend their professional lives cutting-and-pasting rather than writing and drawing, more and more of this type of cock-up is becoming apparent.
Somewhere in the BS for RC is the statement than the minimum cover for steel in a RC structure is 50mm, although there can be exceptions in very, very limited cases and for very, very precise reasons.
Floor slab
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Tony McC
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sblewer
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Well thanks for all the help guys.
I have made a decision to allow 50mm above and below the mesh, so have ordered 50mm chairs, then that way I know I have plenty of cover and it allows for laps etc.
I must admit, I really have learnt a lot whilst doing this build, and I have also learnt that Building Control have definitely gone mental.
Did I forget to mention this spec is for a single storey side extension!
I have made a decision to allow 50mm above and below the mesh, so have ordered 50mm chairs, then that way I know I have plenty of cover and it allows for laps etc.
I must admit, I really have learnt a lot whilst doing this build, and I have also learnt that Building Control have definitely gone mental.
Did I forget to mention this spec is for a single storey side extension!
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msh paving
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glad to see you took our advice,you will find it alot better to place the concrete with more cover,tony made a good point about engineers cutting and pasting spec, they have never got the hands in wet concrete to find the probs that would make 25mm cover
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GB_Groundworks
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spec says has to be power floated and with 25mm cover and inexperienced operator that may have been a recipe for disaster, when you come to power float it it has to be just at the right consistency and i don't think i can describe it really. you need to get it just when its setting and going buttery,
spec also says consolidated hardcore, not type 1 etc me thinks its a older one
spec also says consolidated hardcore, not type 1 etc me thinks its a older one
Giles
Groundworks and Equestrian specialists, prestige new builds and sports pitches. High Peak, Cheshire, South Yorkshire area.
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Groundworks and Equestrian specialists, prestige new builds and sports pitches. High Peak, Cheshire, South Yorkshire area.
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sblewer
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I spoke to the Structural Engineer about both of those items, he did confirm he meant Type 1 Hardcore.
I also discussed the matter about powerfloating, and confirmed the slab finish did not need to be powerfloated as it wasn't the finished surface. I have opted to put the insulation above the slab and then 75mm screed, as we are having underfloor heating put in, and he said he was happy to do it that way, it has also been confirmed by Building Control that they are happy for me to do it this way as well.
I also discussed the matter about powerfloating, and confirmed the slab finish did not need to be powerfloated as it wasn't the finished surface. I have opted to put the insulation above the slab and then 75mm screed, as we are having underfloor heating put in, and he said he was happy to do it that way, it has also been confirmed by Building Control that they are happy for me to do it this way as well.