DVD - Interior Home Inspection from A to Z

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Attic Ventilation

Attic Ventilation photos: P 131-P 137, P 148, P 214, P 215, P 220

It's very important that the attic area be properly ventilated to prevent excessive humidity or heat in this area. Even in cold winter months humidity can cause problems in attics. As a result, ventilation to the exterior is required in the winter. In the summer months attics can reach 150 degrees Fahrenheit which adds a big heat load on the house. Check for an adequate number of attic vents. Check the condition of the screens on these vents. They need to be kept clean. Screens help to keep birds and bees out of the attic. Any bathroom fans should discharge to the exterior. Sometimes you'll find them discharging in the attic which will create moisture problems in the attic.

Be wary of ventilation problems with finished attic areas. Often the homeowner will put insulation and sheetrock on the attic walls and ceilings. This enables them to use the attic for livable space, if allowed by the local building codes. However, many times they will not properly ventilate behind the sheetrock and insulation. This will cause the roof sheathing to become rotted from the trapped moisture. Styrofoam baffles can be used to maintain an air gap behind these finished areas. This will help prevent the roof sheathing from rotting.

Take a look at the roofing nails that protrude through the roof sheathing. If the nails are very rusty and have corrosion stains on the wood, then you know the attic ventilation needs to be improved. This corrosion is usually caused by humidity being trapped in the attic. In the winter time you may find frost on the roofing nails due to humidity in the attic. Also, check the wood roof framing for signs of mildew and moisture stains. This too will indicated inadequate ventilation in the attic.

Some houses have soffit vents. These are vents at the base of the roof where it overhangs the exterior siding. Soffit vents allow air to come into the base of the roof in the attic area. This air carries any unwanted heat or moisture out of the attic gable or roof vents. Make sure that the insulation isn't covering any soffit vent openings that will stop them from ventilating properly. Newer houses will have ridge vents. This is a vent at the very top of the roof, above the ridge beam. Ridge vents allow unwanted heat and moisture to escape from the attic through the top of the roof.

Test any attic fans or any house fans located in the attic area. Turn the fan on while you're on the floor below the attic. Make sure you don't go near the fan while it's running. (They're installed to cool the house, not chop-up home inspectors). Attic and house fans need to have adequate vents to discharge the air. If the attic vent openings aren't adequate, then the fan won't operate properly and it will break down prematurely. If you hear the fan making funny noises or laboring while it's operating, then tell the client to have it checked out for repairs. A possible cause of the noises could be the need for additional attic vents. Also, if you put your hand over a wall electrical switch while the fan is running, you may feel a draft. If this draft is very strong it usually indicates that the attic vents need to be enlarged. The draft around the switch is caused from the air getting backed-up in the attic and coming down through the gaps behind the walls.

Some houses have thermostatically operated power ventilators. These are fans in the roof that operate off a thermostat. When the temperature in the attic reaches a preset level, the fan will automatically turn on to cool this area. When the temperature drops enough, the fan will automatically turn off by itself.

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