The House Detective:  by Barry Stone, Certified Home Inspector

Dear Barry: A few weeks ago, my landlord installed an old, unvented gas heater in my apartment. Whenever I use it, the place becomes as humid as a steam room, and mold has appeared on some of the walls. I’ve complained, but my landlord says the mold is caused by my dogs. Does that seem plausible, or is the mold caused by the heater?  Elizabeth

Dear Elizabeth: Mold is caused by excessive moisture. The exhaust from a gas-burning fixture is mainly carbon dioxide and steam. Most gas heaters are vented to the outside, but an unvented heater expels exhaust, including steam, inside the building. If the mold began after the heater was installed, then the cause is obviously moisture condensation from the steam that is emitted by the heater.

As for your landlord’s canine excuse, that’s a dogged ploy if I ever heard one. Who ever heard of mold being caused by dogs? The unvented heater is a health and safety hazard and should not be used. Furthermore, if combustion problems ever occur with that kind of heater, you could have carbon monoxide instead of carbon dioxide, and that could be deadly. Your landlord should address this matter immediately. First, the gas heater should be replaced with a vented heater, and the replacement should be done by a license heating contractor. Then, the mold should be mitigated by a qualified expert.

Dear Barry: : Our laundry is located on the second floor, directly adjacent to the bathroom. Whenever I run the dryer, the bathroom becomes very humid if the door is shut. I’ve also noticed something like black soot on the bathroom walls. I wash it off, but it always comes back. What could be causing the humidity and the soot, and what can I do to resolve this?   Debbie

Dear Debbie: Here are two possibilities: The vent duct for the clothes dryer may be connected to the bathroom vent duct in the attic. This would allow steam from the clothes dryer to enter the bathroom through the ceiling vent.

Another possibility is disconnection of the dryer vent inside the wall or ceiling of the bathroom. This would cause the moisture from your clothes to vent into the wall or ceiling cavities, raising the humidity in that room.

Another concern is that the “soot” on the walls could actually be black mold, caused by the excessive moisture condition. If so, this would raise health concerns for your family.

To evaluate and resolve this situation, three things need to be done:

1)  A licensed contractor should investigate the path of the dryer vent to determine whether it is disconnected or not properly vented to the exterior.

2)  The wood framing should be inspected to determine whether moisture exposure has caused fungus infection and dryrot.

3) The area should be evaluated by a qualified mold inspector to determine if mold is the problem and if mold remediation is needed. Air samples should be taken from wall cavities to determine whether there is mold behind the drywall.

Dear Barry: Construction of our new home was recently completed, but four days before the closing, vandals broke into the house. They stopped up all of the drains and turned on the faucets. The builder found the mess in the morning. He immediately replaced the carpeting and some of the drywall, but he dismissed the possibility of mold. We are confident that he can repair all of the water damage but are concerned about future health issues in the home. Because of this, we may walk away from the transaction. Do you think we are overreacting?  Ken

Dear Ken:Your concerns about mold are reasonable, but this should not become a deal-killing point of contention. Mold may or may not be an issue in this situation, but the matter needs to be determined, one way or the other.

Mold typically occurs when there is a prolonged moisture condition. In this case, the moisture may have been addressed before mold had a chance to develop. A mold report would provide the answer to that question, and the builder should be willing to go that extra step to resolve your final concerns in the aftermath of the vandalism. Instead of dismissing the issue, he should hire a qualified mold inspector to evaluate the property and provide a comprehensive mold report.

Aside from the health effects of mold, there is another consideration in this matter: the issue of future disclosure. Flooding of the home is now a part of the property’s history. When you eventually sell the home, this will need to be disclosed to future buyers. A clean mold report can prevent that disclosure from raising major concerns. On that basis, the question of mold needs to be answered by a qualified professional.

Dear Barry: I recently had a flood problem in one of the apartments that I manage. The unit was vacant, and several weeks passed before the moisture condition was addressed. Now there is mold on much of the drywall. Everyone I ask has a different opinion about mold. Some say I should hire a contractor who specializes in flood damage. Others say I should get a professional mold inspection first. And one person says I should simply clean the mold with bleach and repaint the walls. What do you say?  Don

Dear Don: The problem with mold today is that is can no longer be viewed as purely pragmatic issue. The overriding consideration has become liability. The days when mold could be washed with bleach and covered with paint are over.  Mold is now a legal problem, as well as a health consideration.

At the same time, the health affects of mold cannot be dismissed. Some people have been severely harmed by mold exposure. On the other hand, there are cases where moldy walls could be washed and painted with no adverse health consequences to anyone. But much more is at stake than the likelihood of health problems. For example, what happens when a future occupant of the building learns that there once was mold in the building and demands documentation to verify that the mold was tested and that removal was done in accordance with environmental standards and with follow-up air-testing. In that case, you would wish that you had done more than apply bleach and paint.

This is the situation that now exists because of past lawsuits and widely publicized hysteria about the dangers of mold. It is from this standpoint that one must consider matters of mold, especially with rental property.

On this basis, a thorough mold evaluation by a qualified expert is recommended, prior to repairing and refinishing the interior of the apartment.

The House Detective:  by Barry Stone, Certified Home Inspector

Dear Barry: : We recently purchased a home and hired a home inspector to find all the defects. During the inspection, I noticed that the wallpaper in the master bedroom was discolored and was peeling at the edges. When I asked the inspector about this, he dismissed it as insignificant, but I continued to feel uncomfortable about it. Last week, I peeked behind a peeled edge of the wallpaper and found green mold. If I’d known about this, I’d have asked the sellers to have it removed. Shouldn’t this have been disclosed by our home inspector?  Jeri

Dear Jeri: When you asked the home inspector about the loose and discolored wallpaper, he should not have dismissed the issue. His answer should have been something on the order of, “I don’t know for sure if there is a problem, but the condition of the wallpaper indicates that there could be a moisture related issue below the surface. Therefore I recommend that the wallpaper be removed prior to close of escrow to determine whether there is a problem in that area.” That kind of disclosure would have led to discovery of the mold and would have saved you the cost of mold remediation and wall repairs.

You should contact the home inspector about your new findings and ask that he take a second look at the wall. A common response from many home inspectors in this kind of situation is to claim that the mold was concealed from view and that mold is not within the scope of a home inspection. Both defenses are true and valid. However, competent home inspectors never dismiss evidence of possible moisture damage. That was your home inspector’s primary error.