Tub creek/noise

I have tub/shower that makes a very slight creek/noise when using. It happens only once or twice when moving towards the drain - then stops.

I have looked at things, tighted the drain cover (the screw wasn't tighted all the way down) and the noise has decreased but is still there - again slightly.

It is a very small "tap" noise and again only happens when I first use the shower. By the end of my shower I can't replicate the noise.

There doesn't appear to be any leaks - but it doesn't mean there isn't. This is a 2nd floor bath - concerned about creating a 1st floor one.

Are there any methods to determine what is going on? This is an original bath (10 years).

Thanks for any input.

Mike

What material is the tub made of?

The manufacturers often state in the installation instructions that bedding (supporting) the tub in mortar is optional. Personally, I think that is a major copout. The tub needs to be fully supported as it could hold say 30-60 gallons of water and maybe a couple of people, so the total weight could be over 1/2T. Most tubs will flex if not supported. If there had been leaks, it could also be the subfloor moving since it was weakened by leaks. The ledger board supporting the lip could have loosened over time and you hear that (small) movement as it rubs on something. Have to be there to tell.

I'd be tempted to poke a hole in the ceiling below (unless there is a panel you can remove to look) and see.

Thanks

Believe it or not there is no access panel - I had a plumber in for something else when I first moved in (4 months ago) and he used a camera to check this particular tub - no leaks underneath at the time.

Again - doesn't mean there isn't one now. And other than staining on the ceiling below how would I know?

I honestly don't know what the tub is made of (10 years old I'd assume fiberglass) - and where is the ledger board? Honestly, don't know much about tubs here.

Are you saying there should be no flex at all in the tub? As I stand in it there isn't any that I can feel.

Thanks

A gelcoat fiberglass tub is probably my last choice of material for a tub (well, maybe a steel one). As in most things, some are better than others. The most durable is still probably a cast iron tub.

There should be ledger boards on the wall underneath the edges of the tub to support it (the tub cannot be hung from these, though). The tub should be sitting on the subflooring and be supported with the nooks, crannies, pockets, whatever supported with something solid. Otherwise, when you step on a weaker area, it can deflect, or if the floor isn't flat, the whole thing could warp and bend.

If it isn't leaking, you can probably live with it. Eventually though, most any materials flexed enough,will fail.

Thanks

Since the noise/creak decreased after tightening the tub drain cover could this indicate anything?

Perhaps the drain basket is slightly loose at the tub?

To me, it means that now your drain is helping to hold the bottom of the tub in place. If the tub wasn't bending (deflecting), it wouldn't matter. That's why bedding the tub in a solid material that can support it properly is so important. Tightening will help keep it from leaking. It could last like this for a long time, but fatigue in the plastics and fiberglass in the tub eventually will give up the ghost.