# Mold behind baseboard



## joecaption (Nov 30, 2011)

First I think when I see this is the wall was built wrong.
No vapor barrier. 
Drywall in direct contact with the slab.
MDF baseboard.
Unpressure treated bottom plate.
Wall not built out away from the foundation.
No fire blocking to stop the flow of air behind the wall from the floor.
Someone just attached strapping directly to the foundation.


----------



## bighak (Dec 27, 2012)

It's happening on interior walls. I'm in Canada and it gets cold here. I suspect the moisture condensed on the colder wall behind the baseboard.










All the black spot are mold. Some other wall are worse.


----------



## joecaption (Nov 30, 2011)

High humidly in the room.
That drywall needed to be 1/2" off the floors or it will wick up moisture.
It also should have been primed and painted before the base went up.
Is that wood of MDF baseboard?
MDF will soak up water like a sponge.


----------



## TotalHomeworx (Jan 18, 2014)

That looks like an interior wall, so the moisture is probably from the floor. Cut all the drywall up off the floor like joecaption said. 

Is that hardwood flooring you are putting down? If so, you will have problems. It should have a subfloor under it (like dricore). 

The MDF trim is OK as long as its not directly on the concrete. It usually gets installed on top of the floor.

Run a dehumidifier down in that area constantly to help with the moisture.


----------



## SeniorSitizen (Sep 10, 2012)

Treat the mold and monitor the atmospheric conditions down there before jumping off the deep end attempting to solve a problem caused by others that may not be present anymore. Dew point temperature will tell you just about all you need to know.


----------



## ToolSeeker (Sep 19, 2012)

I would cut about a 1/2" piece off the bottom just to keep spills, mop water, or anything else from wicking up. Doesn't need to be a straight cut or anything your baseboard will cover it. Then maybe put a dehumidifier down there for a couple days and monitor closely. This is of course after addressing the mold, that looks like a small amount so don't go overboard. And don't use bleach buy something for mold.


----------



## Gary in WA (Mar 11, 2009)

If no vapor barrier poly under the slab, figure moisture is from ground. If high RH in rooms, moisture would show at other higher locations other than behind a paint-sealed baseboard., IMO. Actually the newer codes require air sealing different materials where they join to the floor; 
"Floors (including above garage and cantilevered floors) Insulation is installed to maintain permanent contact with underside of subfloor decking.
Air barrier is installed at any exposed edge of floor."* 
AND; "*Walls Corners and headers are insulated.
Junction of foundation and sill plate is sealed." from; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_sec002_par022.htm
So, the bottom of drywall requires held-up above floor (1/4" min. per code) and the joint requires caulking or other air sealing. If no poly (or sill sealer) under the wall, moisture could easily wick through the bottom plate-pressure treated or not, to wet the framing; http://www.greenbuildingadvisor.com...ressure-treated-sill-plates-and-building-code

IMO, removed the lowest 12" of drywall to check the framing for mildew, if careful, you could reuse it; if clean (the paper facing on both sides usually molds). After reinstalling, be sure to air seal all the joints.... I would even add some electrician's vinyl tape to the bottoms of the baseboard to stop any wicking.

Gary


----------



## alvaro87 (Nov 4, 2018)

Hi all,

I'm putting new tile on my townhouse (first floor) and also found a big black spot that definitely looked like mold when pulled the baseboard. I am no expert on the subject so I will appreciate any help on how to tackle this as I have no idea where to begin.

Any suggestion on how I should approach this situation?

Thanks.

Al​


----------



## Nealtw (Jun 22, 2017)

alvaro87 said:


> Hi all,​
> 
> I'm putting new tile on my townhouse (first floor) and also found a big black spot that definitely looked like mold when pulled the baseboard. I am no expert on the subject so I will appreciate any help on how to tackle this as I have no idea where to begin.​
> Any suggestion on how I should approach this situation?​
> ...


 Duplicating the question is not a good idea.
https://www.diychatroom.com/f101/mold-behind-baseboard-645287/#post5675067


----------



## alvaro87 (Nov 4, 2018)

Nealtw said:


> Duplicating the question is not a good idea.
> https://www.diychatroom.com/f101/mold-behind-baseboard-645287/#post5675067


Sorry didn't know how to create a threat so posted it here, but thanks for the advice.


----------



## Nealtw (Jun 22, 2017)

alvaro87 said:


> Sorry didn't know how to create a threat so posted it here, but thanks for the advice.


 Not to worry.:wink2:


----------



## Gymschu (Dec 12, 2010)

Truthfully, you could call in some mold remediation experts and they would destroy the mold and dispose of the drywall where it's occurring. That's what you're SUPPOSED to do, BUT, it's costly, so, what many of us do is kill off the mold with concrobium (sp?) (not bleach, because bleach does not kill the roots) and then cut off the bottom 2 inches or so (wearing a mask) with an oscillating tool or a drywall saw, heck even a carpet knife will do. Put it all in a garbage bag, seal it up good with duct tape and dispose of it. Add in some new drywall where you cut the old out just so you have some backing to re-install trim. Leave a gap between the new and the floor so water won't wick up from below.

Now, the problem with doing it this way is that you have no assurance that you got all the mold. There could be some growing on the backside of the wall or in ductwork, etc. Experts could do a more thorough inspection, but, again, it's very costly.

To add, Zinsser DOES make a Mold Killing primer that you could apply to the affected areas. No guarantees that it works because I've never tried it.


----------

