Joists/plasterboard safe to walk on...?

[GRC]

I've got, above one of my rooms, a ceiling constructed of plasterboard on horizontal joists, and above that, 'attic' space, with an A-shaped roof, with roof slates to the outside. The 'attic' space is obviously not designated as such, as there's no hatch access to it.

If access were ever required to this roof space, how would I determine if the joist/plasterboard combination is safe to walk/crawl upon?

The room is 17ft x 20ft, with the joists apparently going in the direction of the 17ft span. They appear to be spaced at 20 inch centres.

Is there some reference somewhere, if I get the joist size, I can calculate a maximum load based on this and the span, or is it a moot point? Is it likely that the construction can be assumed to be safe for walking upon, since (I assume) the builders are likely to have negotiated it at some point.....? House is approx 6 years old, if that has any bearing (!) on the issue.

Regards, Graham

 

[Thermo]

you should be able to walk on the joists, but dont try the plasterboards. Best option is to board it out if you ever intend to use it for light storage as that hlps to spread the load

 

[chappers]

walking on plasterboard that reminds me my sparky mate once (and only once)employed another mate of ours to do some labouring, after being told not to walk on the plasterboard for about the third time he finally went through, also in the same day whilst drilling through a joist he managed to drill through a gas pipe and electrical cable at the same time.
Just remembered that as yesterday the same bloke asked me if I had a job for him.

Oh yess I said you can start on Monday 2050

 

[DAZB]

Monday 2050.... whas that the time , or the year ?

 

[chappers]

definitely the year

 

[Thermo]

ill laugh if he turns up on your doorstep that day!