Mold Popping Up 1 Year After Rehab

11 Replies

Hoping someone can identify this issue for me. I extensively rehabbed a property beginning of last year and my tenants moved in mid-March. The bathroom was completely redone and a new exhaust fan was installed, but either mildew or mold began popping up in the ceiling of the bathroom recently and it appears to be spreading. The exhaust fan is not tied into the light, so my first thought was that they never use the exhaust fan and the moisture is building up and creating mildew/mold in the ceiling whereas the exhaust fan would properly dispose of if used properly. Based on the photos, can anyone identify the root of this issue and/or provide a solution? Thanks for all of your help BP.

(Sorry for the 2nd photo being rotated improperly)

Was there mold present before the rehab?

Where is the fan vented? Outside or the attic.

Have you checked to make sure it is pulling air out?  It looks like the basic fan.  For a little more $ you can get a better one.

Is the tenant using the fan?

Maybe try hooking it up to the light switch.

If they run the hot water all day, close all the doors and not turn on the exhaust fans this can happen. I would check the water meter to see if there is any abnormal water usage. 

@Bob B. I haven't looked at the water usage, but I do anticipate they're running the water on maximum heat with the bathroom door closed and not having the exhaust fan on. 

Looks like surface mold or should I say mildew.  Never say mold with tenants.  Wipe down with bleach to make sure, kiltz then re-paint.  Definitely install a better fan/vent and not a second one (area is to small for two) directly into light switch. 

One idea is to set the fan up on a motion switch...  That way you can be sure when they enter or exit the bathroom the fan runs for at least a few minutes before cutting off.  That would remove the excess moisture.

Second, vent to the outside...  Looks like mold is in the transition between sheetrock and tile.  Curious if its also in the attic and growing through.  Maybe those transitions are not sealed up good.  Can't see in the pic very well to be sure.

Third, if you didn't use the moisture resistant sheetrock, the sheetrock could be holding moisture.

Fourth, Is there an A/C vent in that bathroom?  Not sure if it would matter but I know the A/C circulating air removes moisture and humidity from the air as well...

I'm no expert, but these would be good starting points and options to investigate in my opinion. 



Where is this property located?

If it vents into the attic right above that room, the vent is doing pretty close to nothing even if it is being used by the tenant.  

Vent the moist air all the way out of the structure.  Tie it in with the light switch.  You may even put a timer switch inline for the vent where the fan comes on as soon as the light comes on, then runs for a couple of minutes after the light is turned off.

I wonder if the tenants rarely run the AC in the summer.  Maybe they are trying to save money.  In my area the AC will knock the relative humidity inside a house down to 50-60%.  Mold loves it up around 70% or higher.

Pull the fan fixture out and look up inside , you should be able to determine the problem right away .

Always buy your fans according to the size of the room, you are required to have a certain amount of C.F.M.  for a certain square footage always check this when buying.

Are you sure there is not a leak on the roof such as the boot for the sewer vent?

This looks like condensation related mildew.   First vent to the outside for the fan and make sure there is insulation in the attic above this room and no air leakage into the room. We have tiled shower ceilings but not with those tiles only with 4x 4's.  Scrub the mildew off, paint with Kilz and a good mildew resistant paint over it. Not sure if plastic cove molding would help.

Other then that there are a couple of previous points on the fan that are important to employ.

Tie the fan into the light switch so it actually gets used.  So many tenants won't run the exhaust fan and then complain about mildew/mold caused by it.   Eliminate the switch for it and when the light comes on the fan comes on.....and vent it outside, do you really need more moisture in the attic? 

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