How to Identify and Prevent Attic Condensation

Attic Condensation is often overlooked. A little water in the attic might not seem like a big deal (how often do you really go up there anyway?), but in the winter it can decrease the effectiveness of your insulation, cause structural damage to trusses or rafters, and lead to water damage on the interior of your home due to ice damming on the roof. Even if you have no reason to suspect attic condensation, rooting it out now can save you thousands of dollars in home repairs in the future.

1. Identify the extent of the problem

To identify attic condensation, you really just need to head on up there and look. In winter, you should actually be able to see moisture. Keep an eye out for water droplets (or frost) on the underside of the roof boards, or on the end of roofing nails. In the summer, you’ll want to look for signs of water damage: water stains, mold growth, etc. How much condensation is too much? Any. That much moisture in the air is not only driving up your heating bill as we speak, but it can be building up to a much bigger structural problem.

2. Check your insulation

The most common cause of attic condensation is heated air from the living area of your home escaping into the unheated attic: when the warm air condenses, it turns into the moisture you spotted on your inspection. While you’re up there, take a look at your insulation. Your problem may simply be that you do not have enough installed (at minimum you should have 15 inches of cellulose or 27″ of fiberglass insulation). Or, the stuff that’s there may be improperly installed. If your insulation is sound, check the drywall and plaster on the ceiling. Most homeowners are unaware that this material plays a significant role in insulation. Improperly finished drywall or plaster can negate the effects of your insulation.

3. Check your exhaust fans

Bathroom exhaust and clothes dryer fans that vent directly into the attic can lead to pretty significant moisture damage. Rerouting the exhaust will cost a few bucks, but that will pale in comparison to the cost of fixing the interior water damage that will result if you don’t nip the problems in the bud.

4. Look for holes

Heated air can also escape to the attic through the holes in your ceiling that house your light fixtures or fans. Check plumbing vent pipes, chimneys, and basically anything hanging from the ceiling. Properly sealing these apertures will not only eliminate a possible source for attic condensation, but reduce heating costs.

5. Call a professional

Unless you know how to check for properly applied plaster or reroute exhaust systems then you should pick up the phone and call a contractor. While I recommend identifying the problem areas yourself so you enter the relationship with your contractor knowing a little about what’s going on, don’t try these repairs at home. Your wallet will thank me later.