[Greenbuilding] mildew remediation

[Brian Uher]

 The building science guys took on the question of mold/mildew, damage,
removal, etc.  This is what I remember (I recolmmend double-checking,
given the seriousness of the situation).

3 things:

1. the mildew can be removed with soap and hot water, maybe a brush. 
Wear a respirator (follow the EPA spec which focuses on protection of
the worker), done.

2. let it dry, then seal it up.

3. mildew and mold do not attack wood structure significantly; rot
does.  Rot is actually an organism designation, as in "rots an smuts",
typically thought of attacking crops.

4. IF YOU DO NOT FIX THE MOISTURE SOURCE IN THE ATTIC, the mildew will
reoccur, this time on the foam and available wood.  Getting above the
dewpoint may not do the trick, since we are talking about mildew forming
in April, not January...meaning the vapor load (volume) is likely the
problem, not the dew point per se.  If they think the moisture is from
outside, then the foam might do it.  BUT...if it is flow from the
interior (basement, wherever) then the foam may not fix it...so seal the
attic plate...

My 2 cents,
Brian




On 10/10/10 8:26 AM, George Tremblay wrote:
> An acquaintance in southern RI suffered substantial mold/mildew
> problems in the wake of torrential rains and consequent flooding in
> this region last Spring.  The damage has been repaired in all areas of
> their home except the attic, where there may have been some leakage,
> and where there has certainly been a longstanding moisture problem.
>  This is a standard split level ranch, with partial cathedral ceiling
> and otherwise what was intended to be an unheated attic.  As we all
> know, these attics are often subject to a lot of air leakage, and this
> one is neither well sealed from the conditioned space, nor well
> ventilated.  The homeowner needs to either create the proper vented,
> unconditioned attic, or switch to an unventilated roof assembly.
>  There is no ductwork in the attic, so they could reasonably go with
> either option.  Here, though, is the question I want to pose to you:
> if they were to choose an unventilated attic and spray closed cell
> foam against the interior of the roof sheathing and around truss
> chords, is there any need to treat the heavily mildewed sheathing
> first?  If so, any suggestions about appropriate treatment?  The
> homeowner is being deluged with conflicting recommendations from
> moisture remediation outfits.  One contractor recommended complete
> replacement of the 8-year-old asphalt shingle roof, which does not
> appear damaged but they would replace the mildewed sheathing at the
> same time.
>
> Thanks, as always, for any advice.
>
> George Tremblay
> Troy, NH
>
>
>
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