Mold on walls

14 Replies

Hello BiggerPockets,

Every cold season my bedroom walls located where the windows are get moldy all the time. A few questions maybe some experts can help me with -

1. What can i do to prevent mold from building up?

2. Should i replace the insulation and dry wall?

3. Do windows need to be replaced? the edge on the windows are also get moldy every cold season.

Thanks,

Eric

There is only one way to stop mold. Find the location where you are getting to much moisture. Could be a leak in the roof or a leak in the wall. But more likely it is a leak somewhere where the window meets the insert to the house. 

If you have mold then yes you would need to replace the drywall and insulation. Of course after you have found the source of the problem

My best advice is to download the booklet "A Brief Guide to Mold, Moisture and Your Home" from the EPA website. Read the other information about mold on the EPA website too.

http://www.epa.gov/mold/brief-guide-mold-moisture-...

You need to have dry air circulating in the home. In the winter time condensation can easily build up on the windows because of the difference in air temperatures between the inside and outside of the home. If you don't have forced air circulating in the space, then put a space heater below the window.

If the mold has permeated through the drywall, and is not just on a surface that can be cleaned, then you may need to replace the drywall.

Check with your local utility company to see if they offer free energy audits. Then address any insulation issues you find. Good luck!

'MOST' windows are flashed and sealed incorrectly if at all.  The ONLY place I have seen correct info on window flashing is a site by Alberts roofing somewhere in the East part of the USA,,,but it is available last I looked on the www.  If you cant search for it I may be able to find an old link.

Guess to attack the issue head on,,,what kind of window is it?Newer?with nailing fin or replacement? Sheathing? house wrap? siding? Possible condensation site? Plastic vapor barrier?ANY vapor barrier?  AND your location does help as each section of the USA and the rest of the world does things differently for there specific location and climate?

I guess if it were mine and I didnt know where the water was coming from I would be tempted to take off interior sheetrock (or plaster) and have someone with a water hose on outside while I watched inside for where it leaks.  IF that didnt find it either it may be cold drop of the window condensing water OR a direct air leak causing condensation.  I would get several cans of the low expand foam for doors and windows (brand name of 'Great Stuff' is just one of them) and spray foam complete entire window bay from top to bottom.

If that stays dry thru a couple cold or wet spells drywall over this area with either drywall rated as moisture proof,,,mold resistant,,, or even use cement board tile backer(that should NOT harbor mold)...Paint to match

I dont know if there is much you can do if its condensation on the window besides being vigilant about wiping it up as it accumulates. You could also try recaulking around the inside of the window where moisture could sneak into the walls; i.e. where trim meets the window frame. You'll still get the condensation but caulk will hopefully keep in on the side that you can continue to wipe dry and clean when mold does continue to appear.

Thank you very much for the helpful replies. @Marcia Maynard the reading about molds was very helpful!

I don't think its a leak in my window or roof because it has not rained or snowed, just very cold recently and when I turn on the heat, condensation happens on the windows and my walls start to get moldy. Funny thing is that it is just the wall with windows has molds.

Should i scrap off the old paint, spray moldy areas with bleach then repaint the wall?

QuoteReportJan 01, 06:10 PM

Hello BiggerPockets,

Every cold season my bedroom walls located where the windows are get moldy all the time. A few questions maybe some experts can help me with -

1. What can i do to prevent mold from building up?  Jeff-(You must first find the source. This issue to me sounds like a bad window. If these are double or triple pane windows you might have a blown seal which allowed the gas charge to escape. This will cause the windows to sweat from the temperature differential from inside and outside. This is most common during the cooler months of the year. You can sometimes change out the panes but most likely you'll need to replace the whole window).

2. Should i replace the insulation and dry wall? Jeff-(I recommend an inexpensive moisture meter to determine where to stop when removing the affected Sheetrock, (you want to have a reading of no more than 17% on your meter otherwise remove it, it's cheap and so is insulation), and would surely recommend replacing the insulation that you find any growth or moisture on).

BLEACH IS NOT A MOLD KILLER ON THESE SURFACES. Beside being a carcinogen it's not effective in killing the roots of the mold. Use only products like Microban, or Shockwave. These are proven to be effective and are also certified by mold remediation companies and industrial hygienists.

3. Do windows need to be replaced? the edge on the windows are also get moldy every cold season.

Thanks,

Eric

Please feel free to contact me if you have any questions and I'm always happy to help!

Jeff

Is it only one room that has this issue?  It could be that there is little/no insulation in that exterior wall.  I have seen older homes where the insulation has settled or fallen inside the walls.  The bottom 3 feet of the wall are insulated but there is nothing in the top half!  

The temperature difference between them could be causing condensation to form.  Think of the moisture that builds up on the can of your favorite cold, tasty beverage.  Drywall is not very fast to dry out, so it may be acting like a sponge (holding on to the moisture) and creating a perfect place for mold to grow.  If you are not able to spot the source of the moisture, you will just keep putting on a band-aid rather than curing the problem.  

Once you get the source fixed, there are steps that can be taken to prevent future growth.  (Full disclosure:  My primary job is being a Store Manager for PPG Paints.)  PPG Paints has a few products that have antimicrobial properties.  Their Manor Hall and Pure Performance lines are great choices for residential work.  Their Speedhide Zero is a commercial product that also has those properties.

@Eric Tsang - condensation build-up on interior surfaces is an indication that you may have too much humidity inside combined with the interior and exterior temperature differentials.  Are there stand alone or central humidifiers running, lots of stove top cooking, long showers???

I would put a mold cleaning agent on it you can buy at a big box store and most small stores.  THEN put a dehumidifier right where mold persists and see if it comes back then. Fven a small fan 24/7 running against this window glass may be enough to fix what ails it.

You have active mold spores alive there,,,you wipe off the mold and spores regenerate.  They may not be able to if its dry enough

Originally posted by @Eric Tsang :

@Michael Paris I do not have central humidifiers running and this is a bedroom on the third floor. The bedrooms on the second and first floor does not have this mold problem.

Will a central humidifier solve this problem?

 The mold results from excess moisture (manifesting as condensation), so no, adding moisture will not solve the problem. Ascertaining the cause of the excess moisture (relative to the outdoor humidity and temperature) may help with the condensation that's leading to the mold.

Its probably a leaky wall / condensation issue. Many windows condensate in the winter, which signifies humidity inside the home- but that doesn't make the walls grow mold- maybe just the window sill or frame- from being wet all the time. The walls, or some portion of them are probably leaky, and the warm, humid interior air is escaping into the wall cavity, hitting a cold surface, and - bingo- condensation. If you want to fix it for good, ideally, you would remove interior wall surface, insulate and seal up well, put NEW wall surface on, being sure that it's air tight. 

Originally posted by @Eric Tsang :

Thank you very much for the helpful replies. @Marcia Maynard the reading about molds was very helpful!

I don't think its a leak in my window or roof because it has not rained or snowed, just very cold recently and when I turn on the heat, condensation happens on the windows and my walls start to get moldy. Funny thing is that it is just the wall with windows has molds.

Should i scrap off the old paint, spray moldy areas with bleach then repaint the wall?

 It's condensation building up on the inside, which feeds the mildew.

Rather than tearing out your house as everyone else suggests, it'll be something like caulk round the inside of the window (where it meets the wall). Essentially, cold air is entering the house, meeting the warm air from your heater, and causing the condensation. Find that cold air, and you have your solution.

If you have old windows, check the window putty for the individual panes. Again, they can fail in a bad way, especially if it's on the sunny side of the house. Fix with either new putty, caulk - or replace the window if the windows are older than your father.

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