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Bathroom subfloor damage

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  • Bathroom subfloor damage

    First of all, sorry if I use the wrong terms as I describe my problem. I'm fairly new at this.

    So, I am currently in the process of renovating my bathroom and I found something that makes me a little nervous. The floor used to be 1" tile on top of poured concrete with wire mesh backing. I have pulled all of that up and I'm down to the plywood subflooring. I plan on putting down backerboard and then ceramic tile on top of that.

    The problem is best illustrated by photos which I am including here.

    If the damage at the tub didn't seem so extensive, I'd just put down the backer board and be done with it. However, the extent of it frightens me a bit. Will it be okay if I leave it? Is there something I can fill it with before putting down the backer board? Should I try to replace the plywood (this is likely to involve removing the tub which I do not want to do)?

    Any help would be appreciated.


  • #2
    I can take more pictures if it helps.


    • #3
      If the wood is "punky" around the tub then rest assured its waterlogged underneath. best take out the tub and re-do the whole sub floor. I'm sorry it comes to this. Water travels in the most obscure places and causes problems. concrete board will not solve the problem. it'll makes the floor hard again but the sub floor is still springy.


      • #4
        water damage

        water damage areas need to be looked at and fixed to prevent any further damage. there is no shortcut unfortunately



        • #5
          New house about 6 months old. One-year warranty on house.

          Master bathroom is long narrow, about 13 feet long, tile shower and bathtub on one side, two sink counter/cabinets on the other.

          Noticed grout appearing discolored and some efflorescence (white crusty stuff). Convinced a problem when carpet meet tile on one side got wet, smelling like an adhesive of some sort. Lifted carpet and subfloor wet with more of the white crusty. Then carpet meet tile on other side, wet. So about 13 feet wide.

          Question one: is it mold or mildew?

          After many rounds of debate with builder, I got him to pop up a tile in center and the wood subfloor was wet. Not sopping, but obviously damp/moist/wet – discolored from moisture.

          So we think the leak is the shower.

          Builder tells me subfloor may not be wet everywhere (though the grout is showing same signs throughout bathroom) the subfloor will dry by closing the bathroom up and putting a space heater in there. I think common sense tells me that all the tile would need to come up, expose the wood subfloor to circulation so it dries properly and does not mold or milder.

          I’m concerned that if we don’t expose the wood floor to dry, another couple of months (concerned when out of warranty) mold would have grown or the wood rot, etc. Then I’d be hosed.

          I’m not a builder so; an unbiased opinion would be appreciated. Does the tile need to come up after the leak source is ID’d to properly dry? Wood is not extremely damaged yet.

          Or am I being over cautious?



          • #6
            It is going to depend on the condition of the sub floor, if it is still solid and stable then drying it out would be ok, having said that you never mentioned if the tile is laid on a backerboard or glued directly to the sub floor material, if it is straight on top of the wood then as the wood dries you will probably find the tiles will work loose.

            The bigger issue is the leak in the shower, many showers are still constructed with a thick rubber membrane as a waterproof liner, if the shower is leaking then the liner has a hole/tear or incorrect installation, the only way to fix this is removal of the floor tiles and lower wall tiles and rebuild the shower base.
            Don't let anyone tell you caulk fill fix the problem (it's less than a bandaid solution), unless the leak is at a shower door frame to tile area.

            Most often in your situation mold will be colored black, mold is soft and efflorescence is kinda gritty in texture.
            Little about a lot and a lot about a little.
            Every day is a learning day.


            • #7
              6 month old house water damage

              You have a leak and need to get it checked out by a plumber today. If it checks out ok, then you may have a failed shower pan that is leaking onto your vanity floor causing water damage to your sub-floor, maybe more.

              Take advantage of your warranty right now and get this checked out asap! Find a reputable tile and plumber contractor in your area for an inspection. As far as "mold", the only real way to test is by getting a hygienist which is expensive but is recommended. Mold can be hazardous to your health at high levels and can dissipate throughout your house very easily in the air. Bleach will kill mold but NOT the airborne activity! Very important to know exactly what is going on.

              Once the water issue has been determined, you can then feel confident that the repair will be completed properly without any further issues later down the road (after your warranty expires!)


              • #8
                Thanks for the responses. The order is this from top to bottom. Tile, concrete layer, over a steel mesh, then subfloor is particle board or OSB board. I feel good about the leak getting fixed. My ultimate concern is: Do i need to get all the tile up for the subfloor to dry properly? Or will it dry with all the tile still down?

                I think the leak is coming from the shower head stem. Where the stem comes out of the wall is not tight. But if I turn it so it is tight I can't stand in the middle of the shower. i just found that as i was moving my stuff to not use the shower anymore. Builder agrees that's a concern.