Does your Attic Breath properly?

A well ventilated attic stays dry and free from condensation, mold, mildew, and fungal wood rot decay. Having the proper air circulation is a key to prolonging the roofs' longevity, and preventing damage.

An attic ventilation system is generally comprised of upper vents, such as the common box vents, gable end louvers, and sometimes ridge venting. Lower vents named soffit vents or bird blocks complete the system.

As the warm air in the attic rises an escapes the upper vents, fresh air is drawn into the lower vents. If the upper and lower vents are well balanced this system will work fine.

Of course this all makes sense, but it is amazing that how many attics are found with inadequate ventilation conditions. While I have to say modern construction homes generally have fewer problems, I do see alot of issues in those constructed over 15 years ago, and older.

Older homes that had only gable end louvers and no roof top vents seem to suffer the most. Ventilation of the attic is severely imbalanced in this system, and this allows moisture build up in the winter, heat build up in the summer.

But of course when these homes were built, insulation in the attics was minimal. The heat transfer kept the roof sheathing warmer during the winter. But after upgrading the insulation, less heat makes its' way to the roof. A colder roof = more condensation.

When this home was re-roofed, there were additional box vents installed near the ridge. This was an important improvement.

Here is an example of what happened in the years preceding the roof replacement and new box vents. Moisture stains and growth that looks like mildew. But yet another common problem in these homes was that builders did not understand what happened when the bath exhaust fans were also vented into the attic.

Oh sure they pointed them at the lower soffit vents, and assumed this was adequate. But this was a lazy short cut to say the least. The moisture from showers being ventilated into the attic can create significant damage to the roof system.

Remember that the soffit vents act as an intake. So the moisture may directed out, but it rises with the intake flow, and moisture is dispensed along the roof sheathing in the attic. These bath vents must have a roof mounted exhaust outlet for proper removal of moisture from the space and the home.

 Make sure your attic breathes properly. If you are not sure a home inspector would be happy to check it out for you.