Q: We live in a 90-year-old house, and the previous owners remodeled the bathroom at some point before we bought the house. However, no exhaust fan was ever installed and the ceiling over our shower has become covered with black mold. We assume that this is partially due to the lack of an exhaust fan and partially because it appears that the ceiling may not have been constructed of moisture-resistant gypsum board. The mold is localized over the shower and does not appear to have spread onto the vertical wall surfaces (which are wallpaper on plaster above 8-ft-high acrylic shower panels). We think we can repair this damage ourselves by replacing the ceiling and installing an exhaust fan, but how do we remove the damaged ceiling without spreading the mold, and what do we do if the mold has spread to the wood framing? Is this a task for a do-it-yourselfer and, if not, how do we find a reputable company to do the repairs? Should we have the mold tested to determine the type before remediating?

A: There are several questions in this request, so we will try to answer them all.

1. The reason for mold growth on your ceiling may be due the absence of an exhaust fan. You may want to consider installing an exhaust fan to help with ventilation. However, other elements should be considered, such as does the shower curtain/enclosure extend up close to the ceiling or does the bathroom door stay closed most of the time, even when it is not occupied. With any restroom that contains a shower, ventilating the moist air out of the bathroom as soon as possible helps keeps moisture from accumulating on the bathroom surfaces, which can allow mold/mildew to grow.

2. The mold does not have to be tested first as the type of mold generally does not affect the precautions that should be taken during remediation.

3. If you feel that you can do the work, the necessary precautions include removing all moveable objects from the restroom, installing plastic sheeting (overlapping curtain) at door to the restroom, installing a fan in the window if feasible, wearing clothing (that can be disposed of if needed) and wearing a N-95 type respirator during the work.

Once these steps have been taken the following methods should be considered:

Remove damaged ceiling materials and place in plastic bags, wipe the outside of the plastic bags with a detergent solution and place outside the house.

Using two people during the operation would be helpful so that the person inside the bathroom can hand out cleaned bags with debris to the other individual to take outside of the house being careful to not spread debris into other areas of the house.

Clean up any dust debris in the bathroom from all surfaces with wet rags and a detergent solution and place in plastic bags for proper disposal.

Dispose all plastic bags with debris in the normal trash.

4. If the mold has spread to the wood framing, then clean the framing with a wire brush and wipe it with a detergent solution. However, if the wood framing is severely damaged, it may need to be replaced.

5. If you do not feel that you can do this work, then consider hiring a contractor to complete the project. For contractor referrals contact a local mold or environmental consultant.

Thanks to Rick Anderson, a professional engineer and facilities director for EFI Global, a firm that provides mold investigation and indoor air quality services internationally.

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