On Sat, 22 Aug 2009 03:12:59 -0700 (PDT), ppmoore wrote:

For now, I used a coat of varnish on the inside wall and then repainted.

All that will do is trap the moisture in the wall (assuming the wall
is actually damp and you don't just have condensation) and cause the
coating the fail again.

You need to find out, or work out, why the interior wall is damp not
just splash waterproof coatings about willy nilly.

All the normal questions:

What is the walls construction?
Are there anly leaky gutters or down spouts that wet the exterior of
the wall?
Is the room heated?
Is the room ventilated?
Have the windows being changed from single glazed normal casement to
double glazing?
Is the room used for drying things? clothes, etc
Is the room close to a kitchen, bath or shower room?
Has there been any furniture close to the bit of wall with mold?

--
Cheers
Dave.