Mold is often very happy to grow on a basement wall or under a sink if the atmosphere is humid enough, but it can also form practically invisible infestations in cracks and crevices, inside your walls, or under paint or wallpaper. You may not see it and you may not even smell it at first, especially if it's a low-odor type or growing in an area that doesn't exchange a lot of air with the inside of your home, but that doesn't mean it can't cause problems. An unseen mold infestation can cause or aggravate serious health conditions, damage the structure of your house, and go hand-in-hand with potentially even larger problems such as hidden water damage. Here are some signs you might not recognize at first as being indicative of a mold problem, but that might point to one all the same.
Allergy-like symptoms If you or any member of your family is experiencing hay-fever-like or cold-like symptoms (these typically involve the respiratory system and mucous membranes) such as sneezing, runny nose, and itchy or watery eyes, or if someone with asthma or another respiratory problem is experiencing attacks for seemingly no reason, an air quality problem could be at issue here. Once you've ruled out an allergy for the allergy-like symptoms (or, of course, if you test as having an allergic reaction to mold) it might be a good idea to go through your house and investigate for unseen producers of mold spores, such as a hidden colony tucked away in a crack somewhere.
Investing in a quality air cleaning system can help rid the air of allergens, so if you're having a reaction to dust or pollen this is a good idea, but if you have a source of mold inside your home the air cleaning system won't be able to keep all the spores out of the air and you'll need to strike at the root of the problem in order to make a difference.
Blistering of paint or wallpaper In areas around windows and doors, blistering paint can be a sign that condensation has collected and created a humidity and moisture problem. Blistering paint is just the beginning; under the loose layers there is a humid, close environment perfect for mold growth. You'll have to address this problem immediately if you want to keep mold from settling down there. This, along with the condensation that continues to collect, can damage the structure of your windowsills over time.
Signs of water damage If a watermark appears on your ceiling, you can assume that the leak has been working its way down from the roof for a while, giving any enterprising mold spores a head start on settling down and starting a family. If you observe water damage such as buckling or warping of wood floors, you should assume there's a moisture problem until proven otherwise, and this moisture problem could mean that you have mold growing between or even under the floorboards. Because mold can start growing within just a day or two of water damage, any damage that's gone unnoticed for a while is highly likely to be a breeding ground for this problem.
These signs can indicate that you either have a mold problem in a hidden spot or are heading that way quickly. Investigate when these signs first appear, and if you're lucky, you'll be able to escape with minimal damage to your budget, home, and health.