Why is there Frost in the Attic?
Frost in attic caused from water vapor that reached its dew point on nail penetrations
Why is there frost in my attic
When a home has a build-up of moisture and lacks condensation management items, frost occurs in the attic during the winter months. Condensation is basic science and is seen almost every day. Fogged-up mirrors when bathing, dew on summer grass, water droplets on a glass of ice water, or frost in the attic! In this specific case, water vapor has reached its dew point when coming in contact with the roof boards' cold underside and formed frost. Frost in the attic is undesirable because it eventually melts. This melting water can show up as leaks. Condensation or Roof Leak? might be some future reading material. These melting spells are very inconsistent. In many newer homes beneath the paint and drywall, a layer of plastic called the vapor barrier resides. This layer stops the transmission of moisture we refer to as water vapor. Very recent homes are using spray foam. The closed-cell foam creates a better insulator than fiberglass batts, plus it will not transfer moisture because it too is a vapor barrier. The advantage of spray foam is its ability to seal off drafts and thermal breaks in the home. These breaks can cause heat loss from the living space below, which can cause frost build-up. A great way to look at fiberglass insulation is like a filter and spray foam as a blocker. Homes that are inefficient at managing water vapor will have frost build-up in the attic. It isn’t easy to eliminate frost in the attic, but there are definite tactics to reduce it.
Frost builds up reasons.
FACT- Homes without the vapor barrier allow water vapor to travel through the: drywall, plaster, lath, and insulation. Condensation will occur on the first cold item, this water vapor touches.
Producers of water vapor - A home that is occupied produces water vapor. Cooking, bathing, washing clothes, and humans produce water vapor. A family of 4 will produce 4 gallons of water through just respiration and perspiration per day! Imagine how fast moisture can build up doing all the chores in a household beyond inhabiting a home.
More efficient homes mean more moisture - As the structure tightens up with better insulation, vapor barriers, and better windows, the adverse effect is a build-up of moisture. New homes have specific HVAC systems to manage condensation, while older homes often do not.
Humidifier-Is a humidifier in use? These things are often used to keep woodwork from shrinking up or keep the home from becoming too dry. A humidifier adds moisture to the home and ultimately adds what we are trying to get rid of.
Old homes that have not been updated can be relatively condensation-free - Why is this? These homes are just good at getting rid of condensation because they are incredibly inefficient. Air travels through them, solving the problem. No weather wraps, no vapor barriers, minimal insulation, single-pane windows, and a high heat bill.
Lack of ventilation - Attic ventilation is an ally that can help even if some other key elements are missing. Attic ventilation can exhaust even the most moisture-ridden attics if done properly.
Minimal insulation - Insulation and ventilation go hand-in-hand. Insulation resists heat loss which can slow down condensation.
Understanding the “Why” will help determine how to minimize the frost or condensation build-up in the attic.
Condensation is hard to stop but can be checked with proper management methods. As you can see, there are many contributors to condensation, which often appears as frost in the attic. Some fixes can be simple, like shutting off a humidifier or installing a timer on a bathroom fan. Others can be much more in-depth and costly. Target the why. Many times this isn’t a roof issue, but it doesn’t mean Rooftop Solutions doesn’t have connections to help you resolve this. Give us a shout, and we’ll send you in the right direction.
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