here's a link to a site that tells why NOT to use Bleach...in short it will kill mold on hard non porous surfaces. Wood is a porous surface and bleach should not be used....
Thus, chlorine bleach should not be used in mold remediation as confirmed by OSHA's and EPA's updated recommendations and suggested guidelines. The use of bleach as a mold disinfectant is best left to kitchen and bathroom countertops, tubs and shower glass, etc. Why Chlorine Bleach is NOT Recommended for Mold Remediation. Clorine bleach is corrosive and that fact is stated on the product label (not to mention the exposure hazards of dioxins). Yet the properties of chlorine bleach prevent it from "soaking into" wood-based building materials to get at the deeply embedded mycelia (roots) of mold. The object to killing mold is to kill its "roots". Reputable mold remediation contractors use appropriate products that effectively disinfect properly scrubbed and cleaned salvageable mold infected wood products. Beware of any mold inspector, mold remediation contractor or other individual that recommends or uses chlorine bleach for mold clean up on wood-based building materials.
Some of the off the shelf products that you can use for mold and mildew:
1. Bleach. (sodium hypochlorite) Household bleach is 5.25% as sold in the stores. You can use it straight or cut it half and half with water. As you cut it, it will penetrate better. But is it mildly corrosive and will assault a sensitive nose. Will bleach the color out of any fabric and kill plants if saturated with a bleach solution.
2. Hydogen Peroxide. As sold in the stores, it is a 3% solution and can be sprayed on with a spray bottle. Not as effective as bleach initially, but it does work, albeit more slowly. A very very mild oxidizer. Most non chlorine bleaches are made with hydrogen peroxide and can be used to kill light mold and mildew.
3. Consan Triple Action 20. A combination quaternary disinfectant/mildewcide that is very effective on any mold and mildew. Mix with water according to directions. Key is to keep the side WET for 10 minutes. It has a 99.999% efficacy if label instructions are followed. Faint chemical smell. Very similar chemical to Lysol. Available at big box stores and plant houses.
4. Swimming Pool Algaecide. Another quaternary disinfectant/algecide/mildewcide in a 10% solution with water. Efficacy similar to Triple Action 20 as the active is essentially similar. Still need a 10 minute wet time.
All of the above recommendations are predicated on removing all the mold and mildew you can using mechanical means (brush washing, scrubbing, power washing, etc). These chemicals are not very good penetrants and requires you to remove as much of the mold and mildew as possible so the chemicals can be effective on the residue. If you have a heavy mold and spray any of the above on them, it will only kill the surface layer....it will come back almost immediately. So wash the area very well and only use the chemicals on the light residue remaining. Good luck.
After my house in Houston flooded I was told to spray the studs with a bleach mixture first. After that dries follow up with a product called Consant. I used to buy it at Solutions but I'm not sure if they are still in business.
I spent five years of my life as a residential construction superintendent in the hours upon hours i spent with safety training in the oshaa classroom we were told not to use bleach repeatedly. Using a bleach product no matter how watered down is more harmful ingested by whomever is using it than the mold itself. We were always told just to use hot soapy water. The key is to remove all moisture before you enclose the studs or effected area. If the area is dry you should not have any further issues with mold. Mold needs moisture to live it is an organic substance. I would get a moisture meter and make sure it reads its lowest level before you cover it back up. Again you cannot have mold without water.