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Community and Q&A

Getting Rid of Mold on Exposed Framing

green654 | Posted in General Questions on

Building a new house. Framing is almost complete. Roof will be on end of next week. We’ve had a ton of rain. And I went in today to check on the progress and found many wood beams and 2×4 with mold. The underside of entire staircase is moldy. I’m assuming this is not normal for an expensive new build, right? What can be done at this point? I’m kinda freaking out. Thanks.

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  1. Expert Member
    BILL WICHERS | | #1

    You can mechanically remove the mold with a brush, then apply a mold treatment. Wait until you have a bit of dry weather though otherwise it will probably just come back.

    Don’t worry about things structurally though, the mold won’t affect the strength of the wood.


    1. green654 | | #2

      I’m not worried about structure. I’m worried about getting sick from mold on the framing. I’m super allergic to mold and I’m worried this house will take me down. It seems pretty crazy to me that we are paying
      Close to $1 mill and there is mold all over the wood.

      1. Expert Member
        BILL WICHERS | | #3

        Mold is a natural occurrence in wet weather. An abatement company could clear it all out once you have walls and roof up, then keep a dehumidifier running to dry things out so that it doesn’t come back.


      2. andy_ | | #4

        I've got a serious mold allergy too and built a house in the very wet PNW and of course wound up with mold on the framing before the roof was in place. I too freaked out a little bit but in the end it was no big deal. Standard approach of a little mixed bleach, water, and dish soap took care of it and no mold since.
        Mold on the framing is pretty common at that stage. Mold needs moisture to grow, and once the roof is on and the windows are in there won't (or shouldn't) be enough moisture to keep the mold growing. Clean it up and it'll be like it never happened.

        1. the74impala | | #6

          Please don't use bleach. Use Concrobium or similar products made to squash the mold. It may seem less satisfying than bleach, but it actually kills it, not just make it look like it goes away.

          1. Expert Member
            BILL WICHERS | | #7

            Vinegar works too, you don’t have to use bleach.


  2. JC72 | | #5

    It's normal.

    The outdoor air is full of millions of mold spores and they need a food source (ex, wood) along with constant moisture to grow. Mold spores don't care about how expensive the wood is.

    Once the roof and windows are in just clean it off with a bleach solution and move on.

  3. walta100 | | #8

    The truth is mold spores are everywhere you go you can’t escape them.

    Mold requires moisture to grow it would be a good idea to get a dehumidifier running in your house as soon as the windows and doors are in.

    Most new construction homes should have a dehumidifier for the first year.

    If you can keep the humidity under 55% I do not think you will have a mold problem.


  4. green654 | | #9

    Should we have a dehumidifier on each floor to get the house to dry out faster? And don’t we have to remove the mold from the wood? I think it would create huge problems if we didn’t.

    1. Expert Member
      BILL WICHERS | | #10

      More dehumidifiers will speed up the drying process as long as they don’t cycle off. At some point you reach a limit and more won’t speed things up any.

      You can get mold killing primers that can be painted over mold. It’s better to just remove it when you can though.


      1. green654 | | #11

        But how do we remove mold without taking apart all the framing? It’s half the house of wood. No exaggeration!

        1. Expert Member
          BILL WICHERS | | #14

          Get what you can. The usual way to do the work is to use a brush on a pole, and brush off the worst of the mold (wear protective gear when doing this, and especially a respirator). After that's been done, you spray what's left with a mold treatment to kill the remaining mold. The last step if you want to be extra careful is to paint the area with a mold killing primer (I've used one made by Zinsser in the past) to help keep the mold from coming back.

          The most important part is to eliminate the conditions that allowed the mold to grow in the first place, and that's moisture. Once your home is far enough along that it can act as something of a box for air (i.e. walls, roof, and something over the window and door openings), you can start running dehumidifiers to keep moisture levels low enough that the mold won't grow.

          If you're really concerned, I would have a painter come in and spray everything with the mold killing primer after brushing off the worst of it. You'll end up with white-painted framing everywhere, but you'll know that all the mold is dead and encapsulated so you won't have to worry about hidden mold once your home is complete and you're living in it.


        2. andy_ | | #15

          I appreciate and understand your concern, but I think you might be misunderstanding the nature of mold and how it impacts the wood in your house. It's not like if you open the fridge and you find mold on your leftover sandwich and have to throw it out. A little mold on the wood will not ruin it and force you to tear your house down. In fact, I'm pretty sure that all the wood everywhere in every house has at least some mold spores sitting on it all the time. The mold on wood only becomes a problem when it's reproducing at a high rate and spewing spores (especially in a closed space where you're more likely to breathe lots of them in).
          As was said before, once the conditions are not as ripe with moisture the mold won't be reproducing. The bulk of the surface mold can be removed with your choice of cleaning agent or mechanical means. After that, and once the roof is on and windows are in you shouldn't be seeing any more mold growth.
          I personally think that painting over the mold affected areas is overkill and unnecessary.

  5. walta100 | | #12

    The fact is mold is everywhere you can’t remove all the mold spores the best you can do is to prevent mold from growing and reproducing.

    Chemicals can damage some of the spores. Paints can seal most of the spores in place.


  6. capecodhaus | | #13

    All the advice above is helpful. Treat the issue yourself or hire it out.
    Contact a mold remediation company, schedule a site visit, keep an eye on it.

  7. Klaught | | #16

    We had a similar issue a while ago, and we had a professional mold remediation team come in. They assessed the extent of the issue and took care of the mold safely and effectively. It turned out the source of moisture was a combination of the rain and some improper sealing.

  8. jollygreenshortguy | | #17

    There is no need to worry or have anxiety about this. It won't hurt the wood and it won't hurt you while the house is under construction. There's no point in trying to do anything about it until the house is closed in. Once it's closed in the house will begin to dry out.

    Schedule a mold remediation company to give the interior framing a cleaning BEFORE insulation goes in. So you'll need to inform your general contractor and make sure it's scheduled properly. Do your GC a favor and give them as much advance notification as possible, so as not to upset the project schedule.

    The clean up is no big deal and DIYers can do it themselves. But if you're sensitive then have someone else do it.

    Once the house is closed in and cleaned then you can run a dehumidifier. As others have suggested it's a good idea to do that for year or so after completion anyway, as the framing and concrete continue to dry out for quite a long time after installation. It's a good idea to start dehumidifying as early as possible during construction. Dehumidifying shrinks wood and if you've already put in your drywall before you start you may find unsightly cracks appear in your drywall.

    You might also consider good quality portable air filter in your bedroom, running at night while you sleep. That helped me a lot. Eventually my mold sensitivity went away. And though I live in a humid climate now I don't experience problems anymore.

  9. justfishing | | #18

    Is it really something to worry about. As a precaution i might get a fogger and a gallon or 2 of a mold killing product. Not in this type of situation but we used to use sporicidin as it killed mold spores and had a residual affect. There may be better products now.

    There are over 100k types of mold and its in the air everywhere. So you are not getting away from it. 3things for mold growth. 1 is mold spores and we know they are there. The second is a food source. Lots of them in your house. Wood, drywall, soap scum, dead skin etc. the third thing need to grow mold is moisture. That is the only thing you can control. Those mold spore will remain dormant without moisture. Even if you cleaned the wood you would have new spores landing on the framing.

    Hopefully you make the home very airtight so water or moisture is not getting into the walls. Mold is going to grow regardless if high moisture is present.

    Next youare going to insulate the walls and drywall over it. What is going to be a bigger source of mold. The air circulating in the house or the inactive mold sporss trapped in your walls.

    You dont see mold growing without excessive mositure or water leaks. Control mositure and you control mold.

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