drilling into concrete ceiling joists

[samohtom]

Hi. I'm in the process of putting up plasterboard ceilings by screwing onto wooden battens that have been (badly) nailed into the concrete joists of the ceilings in my flat. Flat is ground floor and the ceiling (or floor of the flat above) appears to be block and beam. The place was built in 1973. I want to reinforce the attachment of the timber battens to the concrete joists using steel corner braces and screwing into the concrete. I did this in a couple of places in the bathroom by drilling 40mm 6mm diameter holes, fit rawl plug, fit bracket then screw bracket to wooden batten. My question is, is this ok to do and are there any regs relating to it I should be aware of?! I do know that the bottom of the beams (I'm assuming they are of inverted T shape) are about 17cm across, and the outside bits of the T extend 50mm as I can see this in a place in the kitchen. I can't see a cross section of a beam anywhere though so don't know the depth of the joists. I know there are rebars in there somewhere too as I hit one at one point and had to drill somewhere else instead.

 

[^woody^]

Do you need the building owners permission to drill into the floor structure?

There may be issues of fire spread if creating a void between the ceiling and floor, but if similar to what was there before, then that is no problem

 

[theoldun]

Built 1973, thirty seven year ago.
Are you sure it's block and beam?
Memory is not so good now, but remember Bison solid and hollow cored concrete slabs being all the rage then on flats, but do not remember block and beam in 73.
Could be wrong.
oldun

 

[^woody^]

There are lots of block and beam system built low-rise flats around from the mid 60's onwards