Soft spot in floor

[Crockett]

I recently purchased a home and am working on the bathroom right now. Near the tub there is a 15" x 2" section of the floor that is very soft and dips when stepped on. I thought I could I could put some extra 2 x 6 reinforcements between the floor joists in the basement but found that all the pipes and duct work are right in the way. Any suggestions? Will a new sub floor solve this issue?
thanks as always
Al

[Tom Miller]

Seems like it's not the fault of poor joist support, since it's such a small area that's spongy. I'd be inclined to think the subfloor may be compromised (rotted).

Regards,
Tom

[Warren]

Ditto what Tom said. Now you've got to find the source of the water. Is it a one time thing which was never attended to or something that is still occurring?

[Hellrazor]

The best way to determine what is going on is the following:

Go downstairs and have someone bounce around on the floor in the bathroom and watch what happens.

My bet is a previous water leak ruined the plywood.

[wardprobst]

If I read your post correctly it's 15"x2"? Is is it a strip or plywood subfloor? Either way, a new subfloor may be helpful but need more input.
DP

[Crockett]

Thanks guys. I did have someone jump around as suggested but really did not see any movement. So, as you guys pointed out, it must be a rotted potion of plywood. It is right next to the tub so the suggestion that it may have leaked at one time and rotted the ply wood seems accurate. There was new tub surround installed shortly before I bought the place so they may have had a problem for some time. Thanks as always for your help!
Al