Prtessure wash it ....
Then apply your bleach solution. Maybe 4 to 1. Leave it out in the sunlight to dry, but be careful of checking. Do not dry too much at one time. Use a blower vac to blow away the water. The bleach should kill the mold. Then bring it inside where it's not humid or damp.
Woodturners use anti-freeze to stop larhe chunks from cracking ... etheylene glycol. Search for that technique to see how it's done.
The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)