Attic Condensation

Know Your Attic

Attic condensation can cause damage to the attic space as well as the interior spaces.

What does it take to minimize condensation in the attic? How do you know you have this problem? What are the signs to look for? How do you remedy condensation?

Have You Ever Been In Your Attic?

Most people never go into their attic!

Most people never know whether or not there is proper insulation or ventilation. And if they did go in the attic, most people don't know what they're looking for.

Without proper insulation and ventilation, problems with moisture can cause havoc in your attic – and you might not even know it.

Preventing Attic Condensation

In order to prevent attic condensation, adequate attic insulation is required.

You need to ensure that warm air passing through into the attic space is minimized. The warm from your home should not be slipping through and meeting the cold air in the attic. This is achieved with adequate insulation.

If you are in the garage or a barn where there is no attic insulation, you will notice that the roof sheathing is dry. There is no mold, water or rot in these spaces. That is because there is no warm air meeting with the cold.

So to remedy attic condensation build-up, ensure that no holes, air leaks or bypasses of warm air can pass through the house and into the attic.

How Can I As A Homeowner Look For Air Leakage?

Hire Professionals: You can hire a professional to pressurize the house. This is a very effective and worthwhile test. Not only will air leakage be found in attic areas, they will find air leakage in other parts of the house.

Do-It-Yourself Inspection: A lower tech way to look for air leaks is by being in the attic and looking for any wind blowing dirt or insulation. The air will draw the dirt through an opening from your house into the attic.

One more way to look for an air leak is by light. Leave all the lights on in the rooms below the attic floor and look for any light filtering through. Of course you will need to do this at night.

Attic Condensation

It is common for poorly vented and insulated attics to develop attic condensation. This condensation can form droplets of water and accumulate into the insulation below.

This accumulation can leak through the attic floor and into your living space. It can also cause mold to grow on roof sheathing, trusses, rafters and ceiling floor.

If this condition is left unattended, mold can continue to grow into the living space. When warm air flows from your living space into the attic, it can meet the cold surface of your roof and convert to condensation.

With proper insulation and vapor barrier this will not happen.

In the winter the condensation will form frost and in the summer this condensation can grow mold.

Looking for Signs of Moisture

The first signs of a condensation problem in your attic might show up during a re-shingle on your roof. If there are signs of rot on the roof sheathing, then there has been prolonged moisture in the attic.

Other ways to look for attic condensation is to inspect the attic roof trusses, sheathing or rafters (you’ll need to access the attic hatch from the interior of your home).

Look for condensation or mold inside the attic cavity. If the insulation seems flattened and packed-down then this might be a sign of condensation.

This will be very evident with loose-fill fiber cellulose insulation (paper). This insulation absorbs moisture readily. Give it the "smell" test. You might smell mold or a strong musty-odor. This musty odor can transfer to your living space especially during the hot summer months.

It is wrong to assume that your first response will be to increase attic ventilation. This will only increase air flow and increase the moisture problem.

The best way to fix a wet attic is to stop air flow - stop the air leakage of the warm air from your home into the attic. Your attic is suppose to be cold in the winter and hot in the summer.

Throughout the winter, while your heat is on in the house, your warm air is trying to push itself up to the top floor ceiling and into the attic. Not only will the house be warmer by blocking the air leaks, you will also prevent condensation from forming in the attic.

Once all the air leaks have been blocked, you might need to replace the damaged insulation. While replacing your insulation, take extra measure to increase your attic insulation. This is a good time to do that.

Where’s Possible Air Leaks?

Insulation Batts: Possible air leaks could exist through ill-installed insulation. This is especially true of polyurethane batt insulation.

If this insulation is not laid in a criss-cross pattern, then the spaces between the batts could be an avenue for warm air to migrate through.

Pot Lights: Pot lights could pose a risk as an air leak area. Pot lights need to be properly sealed. It is best to avoid placing pot lights on the ceiling next to the attic floor. For many homes this means the second floor of their home.

Bathroom Fans: Bathroom fans can also be another risk for air leakage. Bathrooms fans are required to vent to the exterior with an insulated duct. This duct should be metal and sloped to the exterior.

Oftentimes, I find flexible, un-insulated bathroom ducts lying flat along the attic floor. This is a recipe for condensation. This condition will need attention.

Plumbing Stacks: Plumbing stacks are sources for air leakage. They must be properly sealed as they pass through the attic floor.

Chimney Stacks: Chimney stacks will also be a source for air leakage.

Cables & Wires: Also ensure properly sealed electrical wiring and cabling.

Space in Partitions: Look for air leaks at partitions or load-bearing walls. Concrete partition walls (fire separation walls) in row housing are commonly a culprit for air leakage.

Walking In The Attic

If you are going to venture into the attic, there are some basics you might want to know before you go up there and walk around.

The attic wasn’t designed for you to be walking around in it. You will have to respectfully and carefully do so.

Walk along the floor joist. If you walk between the floor joist, you will most likely end up through your ceiling below.

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