Uh oh, I've got mold in the shop

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  • atgcpaul
    Veteran Member
    • Aug 2003
    • 4055
    • Maryland
    • Grizzly 1023SLX

    Uh oh, I've got mold in the shop

    Early spring I noticed some spots on the drywall on the ceiling of my shop/garage. I first thought there may be a leak. We had a lot of rain, but the drywall wasn't spongy. I did think mold back then, but I'm a huge procrastinator and stupidly hoped the problem would resolve itself.

    3 years ago a tree fell on the shop roof and let water in. I replaced all the wet insulation and only a small section of ceiling needed to be patched. The spots weren't under where the original leak was but now they're in a lot of places.

    Anyway, fast forward to now. I haven't been in the shop much this summer and it does feel moist in there. There are many more mold spots on the ceiling. I started running the window AC in there to dry it out.

    My biggest fear is that the mold has migrated from the top down but after poking many of the spots with long sticks (it's a 10' ceiling), the drywall doesn't budge so I think it's on the surface only and not on the roof side.

    I was thinking step one would be to use a Swiffer mop to try to wipe off the mold. It seems to be affecting the sections of ceiling I didn't prime so it's "raw" drywall. I don't want to get it too wet but the mold has to be killed, right? Should I prime over it when I'm done? Will that kill it, too?
  • Black wallnut
    cycling to health
    • Jan 2003
    • 4715
    • Ellensburg, Wa, USA.
    • BT3k 1999

    #2
    You might check with your paint supplier. I think there may be a paint that has fungicide added in. However I would be tempted to replace it all; gypsum board is relative cheap, long term mold problems can at worst lead to serious health issues.
    Donate to my Tour de Cure


    marK in WA and Ryobi Fanatic Association State President ©

    Head servant of the forum

    ©

    Comment

    • vaking
      Veteran Member
      • Apr 2005
      • 1428
      • Montclair, NJ, USA.
      • Ryobi BT3100-1

      #3
      mold/mildew is a living organism. If you want to get rid of it - you have to kill it first.
      A vinegar solution in my experience works well to kill mildew.
      Alex V

      Comment

      • pelligrini
        Veteran Member
        • Apr 2007
        • 4217
        • Fort Worth, TX
        • Craftsman 21829

        #4
        Bleach will also work too.

        Make sure you don't have any roof leaks.

        What it really sounds like to me is a ventilation and possibly insulation problem. Is your shop attic space ventilated? ridge vents, soffit vents etc.? What type of insulation? Papered? any vapor barriers? Location?
        Erik

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        • dbhost
          Slow and steady
          • Apr 2008
          • 9209
          • League City, Texas
          • Ryobi BT3100

          #5
          IF the mold is only on the inside, and not the roof side of the ceiling, then kill it, and find out what is causing the moisture problem in the shop. Since you mentioned it was only on the ceiling however, and not your walls, I suspect gravity is pulling the moisture down from above. Get up in the attic , or whatever the void is between the sheet rock and the ceiling, and find out if you still have a leak. Gypsum board USUALLY gets spongy when it gets wet, but I have had some that for some reason or another didn't...

          Once you have determined where the moisture is coming from, fix the leak, humidity, ventilation problem.

          Once you have the continuing problem solved, you will need to use plenty of PPE such as gloves, respirator, and even a painters jumpsuit you can change in / out of just so you aren't dragging mold / spores with you when you go in / out of the shop. Thoroughly, and completely kill every bit of mold you come to using commercially avaialble mold killers. (Home Depot, Lowes, and others have lots of options available, take your pick.).

          Once the mold is quite dead, proceed to thoroughly clean the area, and then finally repair any damage, prime and repaint with mold paint additive in your primer, and paint.

          I know it is a lot of work, but you and your family are far better off doing the extra work now, and doing it right, than letting it get worse, or doing it wrong and having to do it over again...
          Please like and subscribe to my YouTube channel. Please check out and subscribe to my Workshop Blog.

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          • atgcpaul
            Veteran Member
            • Aug 2003
            • 4055
            • Maryland
            • Grizzly 1023SLX

            #6
            All answers I did not want to read but ya' gotta' do what ya' gotta' do.

            My walls aren't painted (OSB) so I can't tell if it's on the walls. I knew it was a real problem when I took my bike down from the ceiling hoist on Wednesday and there were spots of mold on the rear bike bag.

            I will have to poke my head up into the attic space and hope for the best. I may toss a bug bomb up there first. I HATE spiders!!! That's another procrastination spot for me. The garage used to be open to the roof. I enclosed it with drywall and insulation as well as the walls with insulation and OSB when I made it my shop. When I patched the roof 3 years ago (3 years after I finished the ceiling), I realized there were no soffit vents and no roof vents. I didn't add venting then because where I live, I need to get a historic permit for exterior improvements. New vents may have required an inspection. I know I did the interior electric work to code but didn't have it inspected. I didn't want to create more trouble. Anyway, last year I learned I wouldn't need to have the roof vents inspected, just haven't put them in. I actually bought the square roof vents 4 years ago. I also need to get the round soffit vents.

            When I was in the attic space 3 years ago, the 3 year old insulation and drywall looked to be in good condition, but I suppose there could be a leak, too. It's paper-backed fiberglass insulation. IIRC, the paper is against the drywall and the unfaced side is facing upwards.

            I am hoping it's just lack of ventilation in the shop that has let moisture accumulate and it's only on the ceiling surface. The inside ceiling is not flat--follows the hipped roof--so hot air is getting trapped up there. This is the second year I let the lawnmower in the shop. Maybe moisture from clinging grass clippings is contributing to it.

            Will let you all know how it goes. Ugh.
            Last edited by atgcpaul; 07-26-2013, 12:23 PM.

            Comment

            • pelligrini
              Veteran Member
              • Apr 2007
              • 4217
              • Fort Worth, TX
              • Craftsman 21829

              #7
              Originally posted by dbhost
              Since you mentioned it was only on the ceiling however, and not your walls, I suspect gravity is pulling the moisture down from above.
              Not necessarily gravity. I'm thinking it is condensation on the face of the cold sheetrock.

              We used to have a similar issue in a bathroom, especially during the winter months. It got a lot better when I fixed the insulation and cracked a window when the shower was running. The water would condense on the bottom of the rock and sometimes some mold would grow.
              Erik

              Comment

              • atgcpaul
                Veteran Member
                • Aug 2003
                • 4055
                • Maryland
                • Grizzly 1023SLX

                #8
                Originally posted by pelligrini
                Not necessarily gravity. I'm thinking it is condensation on the face of the cold sheetrock.

                We used to have a similar issue in a bathroom, especially during the winter months. It got a lot better when I fixed the insulation and cracked a window when the shower was running. The water would condense on the bottom of the rock and sometimes some mold would grow.
                Are you thinking that at night the rock gets colder and allows the hot, moist air to condense up there?

                I was thinking about aiming a fan at the ceiling or letting my ceiling dust filter run to circulate the air.

                My ultimate plan was to install a skylight that opens, but that will definitely require an inspection and it's out of my league for money and skill.

                Comment

                • pelligrini
                  Veteran Member
                  • Apr 2007
                  • 4217
                  • Fort Worth, TX
                  • Craftsman 21829

                  #9
                  Yes, that's my thinking. I'm not extremely familiar with the cooler climates, but I have a pretty good grasp on how water vapor works in buildings. I'm betting that your outside temps are getting cool enough, especially in the spring, that the ceiling is getting down to the dew point and collecting the water vapor.

                  The first thing to check would be the integrity of the roof though.

                  I also asked about the attic ventilation and insulation. If a building's attic areas (and walls) aren't constructed properly, ventilated and not properly insulated you can get moisture problems and spur on the growth of mold.

                  The additional air flow might alleviate the symptom, but you should find the cause of the problem.
                  Erik

                  Comment

                  • dbhost
                    Slow and steady
                    • Apr 2008
                    • 9209
                    • League City, Texas
                    • Ryobi BT3100

                    #10
                    Interesting thought Erik, I really hadn't thought of that. In my shop (garage), I know I have to be careful to periodically run the AC in the dehumidify mode to keep ambient moisture levels down, even in the winter. I wish I had a better answer for the northern folks... But yeah, cold side condensation might make some sense, assuming that it is a humid environment in there. I would assume that anything cast iron would have a notable amount of rust on it if there was enough condensation to allow for mold growth though...
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                    Comment

                    • atgcpaul
                      Veteran Member
                      • Aug 2003
                      • 4055
                      • Maryland
                      • Grizzly 1023SLX

                      #11
                      Originally posted by dbhost
                      Interesting thought Erik, I really hadn't thought of that. In my shop (garage), I know I have to be careful to periodically run the AC in the dehumidify mode to keep ambient moisture levels down, even in the winter. I wish I had a better answer for the northern folks... But yeah, cold side condensation might make some sense, assuming that it is a humid environment in there. I would assume that anything cast iron would have a notable amount of rust on it if there was enough condensation to allow for mold growth though...
                      Although I will always align myself with the North, technically I'm south of the Mason Dixon line

                      I would hardly consider summer time here in the "North" any cooler than it is down there. We got torched last week with plenty of humidity.

                      Anyway, I have no rust on my tools--especially my CI TS top which sits below all this grossness. Not a surprise from my previous posts, I do not go to great lengths to protect it (Boeshield or wax).

                      I'm headed to Lowes now to buy a respirator. I'm going to muster up enough courage to poke my head into the attic space and look around.

                      Have you ever seen the movie The Grudge? If you don't like attics, don't watch it. If you do like attics, you won't after seeing it.

                      Comment

                      • dbhost
                        Slow and steady
                        • Apr 2008
                        • 9209
                        • League City, Texas
                        • Ryobi BT3100

                        #12
                        I saw it. For some reason attics don't bug me, but the extra hand in the shower was sort of weird...
                        Please like and subscribe to my YouTube channel. Please check out and subscribe to my Workshop Blog.

                        Comment

                        • chopnhack
                          Veteran Member
                          • Oct 2006
                          • 3779
                          • Florida
                          • Ryobi BT3100

                          #13
                          If you find yourself procrastinating to do this job, you might want to consider farming it out. Hire a pro at remediation and git er done ;-)
                          I think in straight lines, but dream in curves

                          Comment

                          • atgcpaul
                            Veteran Member
                            • Aug 2003
                            • 4055
                            • Maryland
                            • Grizzly 1023SLX

                            #14
                            Bought a respirator rated for mold yesterday. Today I'm running my ceiling mounted dust cleaner and setup a box fan pointing outside at the entrance. The shop air is noticeably drier and less musty. Long term I plan to change out the glass in the entry door with a window so I can have some crosscurrent airflow with the window opposite the door.

                            I also wrung out a Swiffer wet mop and ran it over some moldly areas. I was happy to see that it easily wiped away. I've got to attach it to a longer pole and mix up a bleach solution.

                            I will still get up in the attic to check things out. I also need to install those roof vents but have to set up ladder jacks on the steep roof.

                            Comment

                            • cwsmith
                              Veteran Member
                              • Dec 2005
                              • 2737
                              • NY Southern Tier, USA.
                              • BT3100-1

                              #15
                              You might want to consider getting some kind of humidity guage for your shop and follow up with the expense of a dehumidifier IF NECESSARY.

                              Up here in NY's southern tier the humidity is absolutely staggering at times. In the Painted Post house, the basement is just one big harvest of mold and mildew without a dehumidifier. Concrete walls that are uninsulated are cold and opening windows, even with fans only makes things worse... to the point where I've seen the water actually dripping from the walls. Because of that, we only open the basement windows in the fall when the humidity is low and we keep a dehumidifier running all summer long.

                              Here in Binghamton, the basement is insulated but even then the humidity will approach 90% without the dehumidifier. I keep a gauge here in the shop and right now it's indicating 68%. It's been relatively cool for the last few days and so the dehumidifier hasn't been needed.

                              Mold and spiders seem to go together and I too can't stand either. Luckily the Binghamton home, perhaps being in the city, has a minimum of spiders; but the Painted Post home is heavily shaded with trees and the spiders there are eliminated by the dozens at night.

                              CWS
                              Last edited by cwsmith; 07-27-2013, 06:03 PM. Reason: TYPO
                              Think it Through Before You Do!

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