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Attic Rain in Calgary: Top 8 Questions Answered

When living in Calgary, it is important to learn about certain situations that can arise due to living in our northern Canadian climate. One of those conditions that affect first time home buyers or people new to Calgary is Attic Rain (roof condensation).

#1 | What Is Attic Rain?

Attic rain is simply a form of water damage that can occur when moisture is in the air form’s attic frost/ice in your attic in freezing temperatures. This ice then melts on warmer days and starts dripping water internally.

A normal attic will experience minor frosting and condensation when cold snaps happen; however, this often clears without issues when the attic has the correct ventilation installed. Serious cases of attic rain happen when moisture build up and condensation problems creates layers of ice that can cause extensive water damage when it melts. Damage is worse when cold periods happen for longer periods of time.

Home in Calgary with roof condensation freezing

#2 | How Does Attic Rain Happen?

The ice forms internally when outside temperatures get cold, especially during one of Calgary’s many cold snaps. The science all comes down to humidity levels, the dew Point and when there is a significant difference in air temperature.

 In a nutshell, what causes attic rain is hot humid air coming into contact with the cold surface of your roof in the attic, resulting in the ingredient’s needed for condensation forming. This humidity creates layers of ice and can continue to grow as long as temperature differences and humidity continue to persist.

When warmer weather does arrive, these layers of ice start to melt and unfortunately the water has nowhere to go but into your living space. Sometimes, whole rooms can have extensive water damage, which leave homeowners to believe there is a massive roof leak.

 #3 | What Causes Attic Rain?

When examining the causes of attic rain, you need to look at the underlying conditions needed for condensation to happen in the attic:

  1. Freezing Cold Weather
  2. Humidity
  3. Lack of Proper ventilation
  4. Poor insulation
  5. Improper seals, i.e., Gaps in Vapour barriers

Now there are many situations that can cause attic rain and unfortunately the one you don’t have control over is the outside temperature. We do, however, can control the other variables when it comes to fixing ventilation, insulation, seals, airflow, and humidity issues.

When looking at the top causes, we examine the places where moisture can leak into your attic, such as:

  • Bathroom exhaust fan ventilation with air leaks or every so often when they are not even connected properly.
  • Dryer vents
  • Hood fans with air leaks
  • Spaces between light fixtures
  • Unconnected appliance that connect with the attic space
  • Attic hatches

The main culprit is humidifiers. No matter how good your ventilation and insulation, if the inside of your home feels like a tropical rainforest, you’re going to have ice in the attic on cold days.

Calgary is a dry and cold place in the winter. W4SR understands the importance of humidifiers when combating the dry climate that Calgary has; however, if you have 3 of them set at 50% you are going to have warm moist air in the attic causing attic rain during the winter, even with good insulating materials.

Humidifier know set to high causing attic rain

#4 | How to Prevent Attic Rain

  • The first step is to make sure you don’t have ventilation issues. Common air leaks happen around the vent pipe that goes through your attic, where it should exit the house and not into the attic. This includes making sure you have proper roof insulation, water vapour barriers and good building materials in the construction of your roofing system.
  • Secondly, make sure that if you do have a humidifier, it is not set above 30% in the winter, we actually recommend 20%.
  • Turning on your fans when you take a shower and when you are cooking is key to preventing attic condensation by reducing the amount of slow water vapour build up.
  • Visually inspect your attic during a cold snap and looking for frost building up on the roof deck (underside of the roof). Furthermore, in warmer weather, you can look for damage and discoloration to the decking material, and insulation to see if you had minor attic rain.
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#5 | What Can It Cost to Repair Attic Rain Damage?

Costs can vary from a couple of hundreds of dollars for a simple roof repair to the entire roof replacements and everything that has been water damaged.

Managing the heating and cooling of your home is important. A big aspect is making sure you have a proper building envelope. As with anything for your home, there is a range of products for types of insulation (from batt insulation to spray foam); as well as the simple inclusion of basic building materials such as vapour retarders, and all the proper venting to increase airflow.

In the end, we always recommend paying for professional contractors that install and work on your home properly. The price you pay when contractors cut corners can cost you a lot more eventually when a problem like attic rain occurs.

Vent becoming detached in a calgary home venting humid air in the attic

#6 | Does my Insurance Policy Cover Attic Rain?

When it comes to anything and insurance, the answer generally is, it depends. Firstly, this article should not, in any way, substitute real legal advice and is for informational purposes only. Each home insurance is different and can have varying policies and fine print. What you can do is check your insurance policy to make sure you’re covered. Keep in mind that coverage for attic rain might not be blanket coverage on any cause, and as such the important info is in the details. Unfortunately, attic rain does happen and can take new home buyers by surprise.

New home in calgary valley ridge being constructed

#7 | Why New Homes Are More Likely to Have Issues

As other Calgary roofing contractors have pointed out, attic rain is becoming more of an issue with newer homes. Why?

Homes built recently are being constructed to have an airtight seal that keeps moisture from escaping and therefore becoming trapped within your attic. Systems are in place to circulate this air and exchange the air within your home with fresh outside air.

Some homes don’t even have these systems in place or are not operating enough or correctly.

#8 | Who should I contact to fix attic rain issues?

Professional roofers are the best option as we don’t just specialize with the roof you see from the outside but are also the entire roofing system. Contact us today, and we can help solve your attic rain problems or even help prevent them from ever happening!

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