I grow orchids indoors - currently this is done on a plant stand in the corner of the room. I have a 10 X 16 bonus room over a garage that I plan to convert into an indoor garden room. This room is currently heated/cooled with the rest of the house and also finished with drywall and carpet (which will be removed and replaced with tile up to about 4 feet off the floor - floor to be tiled).

When complete the room will be lit with T12 flourescents for plant growth (minimal heat build up). It will maintain a humidity of 60-80 percent with light air movement and normal indoor air temperatures around 65 - 75 are perfect. The walls/floors will not get any direct watering ever but will experience some overspray from a misting system when watering.

My main concern is humidity and risk of mold - so here are my questions:

- Do I need to remove the drywall and replace it with Hardi board or another material or can I simply paint it with an exterior grade paint?
- Is there a risk leaving this room connected to the rest of the house with the central heat/air forced air system?
- Any other suggestions would be appreciated - Thanks!

Is there an air return for your heat and air system in this room. My main concern is also the humidity and mold . The humidity levels and temperatures you quoted are definitely high enough to support mold growth . The walls would have to be tiled high enough to prevent even misting. Have you given any thought to the ceiling after all warm moist will rise. My personal suggestion would be not to use this room for this purpose an external green house would be the best way to go. If I've missed anything or if you have more questions post back. GOOD LUCK, AC