Bouncy floor joists

[gkular]

I have a run of 4 joists in a ground floor room. They are a bit bouncy. They are not rotted or damaged. I can get access to underneath where there is about 15cm of gap between bottom of joist and floor.

What is the best way to support or stiffen them up. Do I need a jack or something to lift them, then put the support down? Bricks?

 

[footprints]

You can sister them that is bolt another joist to the side, add noggins which are bracing timber fixed to each joist at right angles, beef up the flooring with thicker T&G timber or 18mm ply if the existing is chipboard, also drilling through the boards and screwing them to the joists instead of relying on nails. Any or all of the above will help.

 

[oldbutnotdead]

You can stick bricks under the mid span if you want- no need for mortar, dry stacked is fine. Use slate or pvc window shims to get the level right, make sure there"s something waterproof (slate or DPM) between joists and bricks. And yes you can use a car jack to level them but don't go mad, you might start lifting the joist ends