“Thoroughly cleaned all wood and treated with captan before repairing and put cement board on ceiling.”
While Captan is a fungicide, all the regerence I can find is protecting againts diseacse in fruits and vegatables.
http://www.pestproducts.com/captan.htm
“USE ON:
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FRUIT CROPS: Apples, Grapes, Peaches and Strawberries.
*
VEGETABLES: Seed Treatment Only.
*
BULBS: Pre-plant treatment – Gladioli and Tuberous begonias.
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ORNAMENTALS: Azaleas, carnations, Chrysanthemums, Roses.
*
LAWNS AND TURF”
I did not see where it is used for interior applications for mold control.
” We found some due to a leak behind the shower and ceiling in bathroom. “
A leak in the shower would affect the wall, floor, and ceiling below. Not the ceiling of the shower.
The ceiling of the shower might have mold due to poor ventalatiion and/or insulation.
But I did not see where there an information about the cause of the leaks or the fixing of the leaks.
Once the cause of the excess moisture is removed then then even, if there where any remains of the mold, it should die.