Q: I have mold developing underneath a window in my bedroom. The window faces north-northwest and never has sun on it. I wonder if the mold could be caused simply by moisture accumulating in the room, or is it a more serious problem, such as a leaking window frame?

I have no idea whom to consult. One inspector wrote in his report that the paint job was poor, but didn’t say why. There’s a contractor in my neighborhood, but how do I know he knows what he’s talking about?

I’d like to get someone who could determine what is causing the mold, and why the paint splits off my front window sills within months of being applied. The wood is not soft, and the tip of a knife does not penetrate. Any tips on what kind of expert I should be consulting and how to recognize a reliable person would be greatly appreciated.

A: The mold on your window is either the result of too much moisture and too little ventilation or it could be symptomatic of a more serious problem.

The peeling paint on the front window sills likewise could be a sign of excess moisture or it may simply be that the top coat of paint is incompatible with the undercoat.

If there is a structural problem, it is possible that it’s caused by termites, but we doubt it. More likely it’s caused by a fungus infestation, also known as dry rot. Fungus flourishes in moist conditions. We recommend that you employ a licensed professional structural and pest control contractor to determine whether you have a problem and if so, its extent.

The inspection you had done seems to have been deficient. A “bad paint job” tells us (and you) nothing.

If, for example, exterior caulking was substandard, that may be the cause of water infiltration and the mold. If it’s been going on awhile it could also cause rot. A general building contractor might be of help in identifying structural defects but generally does not have the specialized training necessary to ferret out and identify specific pest control problems, such as the cause of the mold under your window.

As for finding a reliable structural and pest control inspector, we suggest you inquire with the people who use them the most: real estate brokers.

A structural and pest control inspector is part of almost every home sale. Most brokers have a number of pest control operators they use regularly. Tell the broker up front that you’re not thinking of selling (unless you are) but that you have a problem and are looking for some guidance. We think the broker will be happy to recommend a licensed pest control company.

Once you have a name, schedule an inspection. Also ask to talk to the inspector and tell him your concerns. We recommend that you have the entire home inspected and that you be there during the inspection.

It’s possible that the inspector will suggest that he open a test hole or two in the exterior walls to determine if there is hidden damage. This is the case especially if the house siding is stucco.

Our experience is that inspectors do not recommend this unless they suspect trouble. Allow him to do it, but ask him to patch the holes when he’s done.

After the inspection, ask the inspector to talk to you about his findings and ask questions. He’ll probably be happy to take you around the house and show you any problems he uncovers.

A week or so after the inspection you will receive a written report detailing the damage he’s found and the cost to repair it. At this point you can choose what, if anything, to repair. You can also put any suggested repairs out to bid. The cost of the inspection should be no more than $200. We think this is a bargain for the knowledge you’ll get.

If what you have is merely mold, the cause is a lack of sunshine and inadequate ventilation on your north-by-northwest windows. This is especially true if you live in a foggy area.

Mold needs three things to thrive — moisture, food and a temperate environment. The moisture is provided by condensation; the food is the paint or plaster; and the temperate climate is provided by the warmth of your home’s interior.

If the mold is not too severe, clean it up by wiping the area with a 25 percent solution of chlorine bleach and rinsing with cold water. Keeping the curtains open and the promoting ventilation by opening the door and windows (weather permitting) will help keep the mold at bay.

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