Hello,  I had some experience with mold when I had a water pipe break
while away from home for extended vacation.  The water ran for days
in the laundry and made its way through the kitchen and the hallway.
The water drained out through the heat vents and kept from getting the
other rooms in the house.  There was a foot of water in the basement
and the floors and some walls were soaked.

So when the cleanup service came in to dry out the house they of
course had to tear out things like kitchen cabinets on the floor and
the walls to get the wet insulation out.  I was there when the service
was scrubbing the mildew and mold off the framework of the walls and
ask what they were using -- something like Clorox bleach?

They said to never use bleach to try to kill, control or remove mold
or mildew.  I thought well all these years we have been washing the
outside of the house before we paint with Clorox and that doesn't work
so I did some research on the subject.

The cleanup service is entirely correct.  Clorox bleach will take care
of mold and mildew only on the surface but the mold is a growing plant
which has roots that go into the fibers of the wood.  You have seen
wood that has been wet for years and it just crumbles due to what we
use to call dry rot.  It is actually been used up as food for the mold
and mildew until there is nothing left.

There are specialized cleaners for use on mold and mildew.  The
chlorine molecules are too large to penetrate the wood fibers so they
only work on the surface.  The special cleaners go into the wood and
kill the roots of the mold and will stop it for good.  The material
they were using on my home was called "Moldstat" (might not be spelled
correctly) and you can buy it online and also at some of the home
improvement stores.  After the wood was cleaned in the walls they
applied a coat of wood sealer after it had all dried out and then the
walls went back up.  This was a long and costly process for the home.

I actually bought a "fogger" that is used in places like the crawl
space of your home where it is damp and gets to smelling musty.  The
musty smell is the mildew growing.  You run the fogger and the material
drifts onto the surface of all the floor joists and framework and kills
the mildew.  I fog the basement and crawl space twice a year and it
really works.

Of course you would need to test a sample to make sure it does not make
your organ pipes fall apart or something bad before doing the entire
system.  Hope this helps; I sure was fooled by what we did in the past.

Have a great day,
David Fowler