Fire resistance of reinforced concrete

[GB]

Can anyone recommend a good source for RC fire resistance periods and in particular the effects of reduced cover to rebar

I have a hollow core slab with only 15mm cover to the rebar and I am looking for a period which I can use as part of the FR make up supplementing with additional measures e.g boarding or instumescent type sprays.

[wee brian]

If its a hollow core slab then the manufacturer will have info on what period of fire resistance you get from it.

for general RC concrete then there's a table in the design code that sets out recommended cover. years since I looked at that though.

[Fishy]

Just be careful if it's a floor you're trying to upgrade - these require load-bearing capacity as well as (sometimes) integrity and insulation, so whatever protection is applied it needs to be able to deliver that (quite apart from integrity & insulation, if those are what you're after).  I've had to give these to structural engineers to deal with before.

[GB]

Its a 1960's office conversion into domestic accommodation therefore manufacturers info is not available.

It is an existing building over 18m and sprinklers will be provided as part of the new development including the common areas.

I am working alongside the structural engineer on this one as the loads will obviously change.

I have looked at IBC Codes Section 720 which provides some information which has been helpful.