Doubling up floor joists to cope with gym equipment.

[Long 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 = 300kg 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 the following options: 

• doubling up the joists and may be even tripling under the weights rack. 
• take a course of bricks off the sleeper walls and replace the joists by 7" or 9".
• adding steels under the rack
• using a flitch plate between the doubled up joists under the rack.

 

Any advice would be welcome.

Edited February 23, 2021 by jack
Tidied up text formatting from copy/paste

[SteamyTea]

Can you make the jousts deeper.

https://www.engineeringtoolbox.com/amp/beam-stress-deflection-d_1312.html