Ventilation is the Key to Mold Prevention
The reality is that most people don't spend much time in the attic. Those with pull-down stairs may spend a few minutes a year lugging seasonal decorations up and down with barely a glance at the rest of the attic. For those whose only access is a hatch needing a ladder for entry, they may never see the attic. In the course of my inspections I come across mold in the attic fairly frequently, usually of the light or moderate variety, but on occasion I find heavy mold infestation. The homeowners are invariably surprised by the finding of the mold. If you're going to sell the home and there is mold in the attic, any home inspector worth his salt is going to find it and in some fashion the mold will need to be dealt with.
The primary cause of mold in the attic is condensation from warm, moist air in the home convecting up into an attic that does not have adequate ventilation. Ideally the roof is ventilated from the soffits at the eaves of the roof up through to the ridge vents at the top of the roof. That air flow keeps the underside of the roof cool and dry so that the mold spores don't have a chance to stick to a warm moist surface.
Besides a poorly ventilated roof a number of other factors can contribute to mold in the attic:
* A poorly insulated attic floor including air gaps around lighting, fans, plumbing and the attic entrance;
* Vents from the bathrooms, kitchen, and clothes dryer venting directly into the attic;
* Furnaces and uninsulated duct work located in the attic;
* Leaks from the roof, chimney, plumbing vents etc...
The vast majority of mold found in attics is of the light or moderate variety and can be self-remediated or can be removed by a handyman. Check the EPA website for the proper clothing and cleaning supplies to remove the mold.
If you have heavy mold infestation on the underside of the roof call a couple of mold remediation firms for estimates. This could be quite expensive and I know a few clients who have completely replaced the roof, including the plywood sheathing, for less than the cost of the mold remediation.
Remember a well ventilated roof is the key to keeping the attic moisture free. If your home does not have soffit vents or is multi-peaked making it difficult to have an effective ridge vent consider adding powered vents. Solar vents have been on the market now for a number of years and are easy to install, relatively cheap, need no electric power and last for about 20 years – a good alternative for keeping your attic moisture and mold free.