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Moisture in the Attic? Here’s How to Dry it Out

Moisture in the Attic? Here’s How to Dry it Out

When you suspect you have moisture in the attic, you should deal with it as soon as possible. It’s not always easy for homeowners to identify a moisture problem, so we show you how in this article. We also show you how to get your attic dry again, and what to do to prevent condensation from happening again.

Identifying Moisture in the Attic

Excessive moisture may not always be visible, and there may not be enough to make your attic insulation feel wet. But even a small volume of moisture can cause big problems. Here are some of the signs there is excessive moisture in your attic.

  • Rusting on the roof nails inside the attic
  • Dark stains on the timber
  • Visible moisture on the roof sheathing
  • Damage to the roof sheathing
  • Mold
  • Does your attic insulation feel moist
  • People who live in cold climates may see signs of condensation show up as frost or ice buildup on the roofing nails
  • Water drip marks on the attic floor

The above are all signs that condensation or moisture is building up in your attic. Before you get started with drying out the attic, understanding how it got there in the first place is the best way to stop it from happening again.

How Does Moisture Get Trapped in the Attic?

Moisture accumulation most often occurs in the cooler months because the cool outside air holds less moisture the colder it gets. When your attic has excessive humidity, you may see condensation forming on the underside of the roof deck.

Humidity during the winter months can be anywhere from 30 to 50 percent. When it gets higher, you will often see condensation forming on the windows, ceiling, and walls.

Other sources of moisture inside your home include:

  • dishwashers
  • dryers
  • bathroom vent
  • showers
  • washing machines
  • unvented kerosene space heaters
  • light fixtures

An average person will add an additional 3 pints of moisture to the living area just through breathing, so moisture can come from just about anywhere. However, most sources of moisture rarely pose a problem for the attic.

Another common source of moisture are the foundation walls and floor slabs in crawlspaces and basements. The temperatures in these areas can remain fairly stable and will not be an issue most of the time.

Things can change as winter weather sets in and moisture migrates toward an attic that is cooler than the basement. Condensation occurs when warm, moist air contacts the cooler attic surfaces, which can lead to mold, mildew, and wood rot.

A simple test is all you need to reveal a moisture problem. Take a small square of plastic sheeting, about 20 x 20 inches, and lightly tape it to the surface you want to test. Leave it in place for about 15 hours.

When you see condensation beading underneath the plastic, you may have excessive moisture in the slab. Don’t assume you don’t have an issue if it comes up dry, because you will need to test several different areas to be sure.

How Moisture Travels from Basements and Crawl Spaces to Attics

Crawlspaces and basements are well known for being cool, dank spaces often plagued by moisture issues. You may wonder how moisture way down in these areas can migrate all the way up into your attic. The most common culprit is a process known as the ‘stack effect.’

This term refers to the movement of hot air escaping the attic and creating a vacuum as it exits your home through the upper levels. New air from below is pulled upward from basements and crawl spaces to replace the displaced air.

Once the moisture-laden air reaches the attic and makes contact with the cold roof deck area, it condenses back into liquid form, where it can cause all sorts of moisture damage in the attic space.

Many of the openings that allow air to infiltrate the attic are often overlooked, with the most likely suspects including the gaps in pull-down attic stairs, poorly sealed ductwork, and gaps at the interior and exterior walls.

The stack effect can pull a significant volume of air through places where there is an air leak. Condensation is not the only issue because these leaks also cause heat loss that adds to your energy bills.

How to Dry out Moisture in the Attic

A professional examination will often result in a recommendation to improve the attic ventilation system. However, doing this will not always solve an issue with condensation in the attic.

Increasing ventilation alone will lower the temperature of the attic, which may result in even more condensation and reduce the efficiency of the insulation. The best method to control moisture in the house is to deal with it it at the source. Moisture that is migrating from the basement and entering the attic through air leakage can be remedied using various methods, including:

Every house is different, so we highly recommend you have your property examined by a professional. They can determine the best course of action for improving relative humidity levels and preventing excessive moisture in a home.

Manage Air Infiltration

Once you’ve managed to control the moisture that rises from the basement, you still have more options for reducing air infiltration. Eliminating air flow and reducing the stack effect is a good first step. Most solutions are possible as a DIY project, but if you aren’t confident or handy, a professional attic service can weatherize your attic for you.

It’s worth keeping in mind that sealing air gaps will not reduce humidity inside your home and may increase it. However, when humidity is contained inside the living spaces and kept out of the attic, it will not cause any issues.

Are you unsure about how to fix the moisture problems in your attic? Attic Pros provide professional attic services that can clean and restore your attic and ensure it stays free of condensation and the larger problems like mold, wood rot, and pest infestations that usually follow. Call today to learn more about keeping your attic dry.