Doubling up floor joists to cope with gym equipment.

[Endless to do list]

I am looking at using a ground floor room as a gym but would like to ensure the floor is strong enough to cope.

It is a 1930s semi. The floor is a suspended timber floor with 2" x 5" joists at 380mm centres. The room is 3.6m wide but there is a sleeper wall around the perimeter and down the middle, so the max span is 1.8m.
One area will hold my son's weight rack. This weighs 80kg + weights 170kg + him 80kg = 330kg in an area about 1.35m x 0.85m.

The floor seems pretty sound and the joists have no signes of rot or infestation.

I was considering doubling up the joists and may be even tripling under the weights rack. Or alternatively, I could take a course of bricks off the sleeper walls and replace the joists by 7" or 9". Another option would be to double up with a flitch plate.

Any advice would be welcome.

 

[catlad]

Just double them up, I would consider using 18mm ply over the existing floor boards if there is going to be point loads.

 

[Endless to do list]

Thank you catland.