* Fungus damage on the exterior wood (this is in the garden and at the bottom of a huge window) and minor water stains (not wet and they look small and dry) on the inside.

A contractor will be coming tomorrow to give an initial estimate without opening the wall (so he'll be limited this time).

Any advice on how to deal with this if the damage is minor? I was thinking sealing/painting the outside area could help after trying to remove the fungus? What's the best way to get rid of the fungus/moisture on a wall? Thanks a lot in advance.

-wavy

Is the fungus on the North side of the wall / house? If so
then it never gets any sunlight or heat (perhaps) and so
fungus will grow.

Chlorine is a sure fire killer of fungus.

Do you have any photos you can show? Below is a place
to put a link. You can put photos on a photo hosting site
then put a link where we can look at it.

Your message says that it appears the effect of wetness has
permiated the wall. So I would look at the window sill
to see if it's plumb - exactly horizontal. If so then
any damage inside the wall is not so severe as to cause
a structural failure yet.

I would next hammer on the area where the structural beams
are located. The frame of the window , under the window.
If it's a solid sound then again you probably don't have
a severe problem.

I'd ask myself if theres a coincidence that the inside water
and outside fungus are there for different reasons. Maybe
a shower on the inside and a North wall on the outside.
Thus two causes for two indicatons of moisture. Unrelated
thus no reason to think water got into the structure.

There ya go. $0.10 worth.

Good luck.
Andre