Q: We have a large deck that has a buildup of mold and mildew on the underside because of poor ventilation. We have now solved the ventilation problem, but are not sure what, if anything, should be done to kill the existing growth. Is there something that could be sprayed on the underside of the cedar decking?

A: I referred your question to a painter, since they refinish decks. He immediately questioned how much water could cause a large buildup of mold and mildew on a deck, and why there would be any ventilation problems outdoors.

Applying a bleach solution will kill mold and mildew but you would have to worry about the environmental impact of introducing bleach to the soil and any landscape. It may also just treat a symptom of a more serious problem that needs rectifying.

He suggests you address the cause of so much moisture, and wonders if you have standing water under the deck to encourage that mold and mildew growth. He advised contacting a landscape contractor to look into installing drainage in your yard to divert it away from the deck, and the rest of the house, if your deck is attached or adjacent to your home.

To locate some reputable landscape contractors to consult, please visit our site at: Http://www.servicemagic.com, fill out a service request and let us match you with the ideal service professional in your area.

Good luck!
Kathy Maynard