Weight capacity of wooden joists

breanting

Thanks for the very helpful reply weeg. It does indeed seem as though some reinforcement would be needed, which would up my overall costs, and the booth would already be quite expensive. As you've recommended, I've contacted a few structural engineers to get some advice from. If that happens I'll report back here in case it's of use to anyone else. Big thanks to all the help!

breanting

Just thought I'd post my findings here. I've consulted a structural engineer and his analysis of the existing joists in accordance with the requirements of the timber design code (BS 5268-2:2002) concluded that they have insufficient capacity to support the resultant loads from even a small 434kg booth.  He said that "unfortunately we require to satisfy the loading and timber design code requirements". So I guess I'll have to wait until I move and find a place with stronger floors. Thanks a lot to everyone that helped out in this thread, it is much appreciated!