mold

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As a roof consultant I have seen many, many homes with mold in the attic on the bottom of the roof sheathing. Here are some basic things to consider:

1. Call your insurance company. If your covered they will hire a consultant to investigate your claim.

2. Find the moisture source. Are any appliances venting into the attic? Improperly vented bathroom fans are common. These need to be vented outdoors, not just into the soffit! Kitchen vents also need to go outdoors. Spas/hot tubs inside the house give off a tremendous amount of moisture.

3. Is the roof in good shape? Any leaks?

4. Air leakage into the attic space is common. Air leakage through gaps around recessed lights, bathroom fans, attic stairs, etc. allow warm moist air to enter the attic where it condenses and saturates the roof sheathing. In the winter it is not uncommon to see frost and even icicles in the attic! Rusted roofing nails are also an indication of excessive moisture.

5. Humidifiers are dangerous! Where do you think all that moisture ends up?

6. Determine if adequate attic ventilation is provided. This can be calculated by determining the net free area (unobstructed area) of the ventilation provided. A well-designed ventilation system uses soffit vents (located low by the gutter or edges of the roof) and ridge or eave vents (located high or at the top of the roof). Cooler air (compared to the attic air temp) enters the soffit vents and exits the ridge vents. This occurs naturally (hot air rises) and the air movement takes heat and moisture out of the attic. Building Codes and manufacturers recommend a minimum of 1 sf of net free area of ventilation for every 150 sf of attic space. This should be evenly distributed between the soffit and the ridge. If a vapor barrier is provided, the minimum ventilation can be reduced to 1 sf of net free area of ventilation for every 300 sf of attic space. Remember these are absolute minimums, and it is common to provide more ventilation. But even if extra ventilation is provided, the ventilation can be easily overwhelmed by excessive moisture.

7. Ice dams - these are related to poor ventilation and inadequate insulation. During the winter, heat leaks into the attic space and "warms" the roof. This in turn melts snow, which then turns to water and drips to the edge of the roof. The edge of the roof is not over the warm attic and is "cold". The causes the water to re-freeze at the roof edge. This cycle continues and eventually an ice-dam is built-up at the edge of the roof. Water can eventually back-up under the shingles and then melt and drip into the attic or wall cavity.

Many factors can contribute to mold in an attic. To function properly, a roof/attic area must be provided with adequate insulation and a well-designed and properly installed ventilation system.

Hope this helps. I'm happy to try and answer other questions - just email me.

And please visit my website to learn about an Energy-Saving Attic Stair Cover - www.batticdoor.com