Attic Rain in Calgary Homes: What It Is, Why It Happens, and How to Prevent Costly Damage

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newhomewarrantyinspectionAttic Rain in Calgary Homes: What It Is, Why It Happens, and How to Prevent Costly Damage

 

If you live in Calgary or the surrounding communities like Airdrie, Cochrane, Okotoks, Didsbury, Olds, Carstairs, Chestermere or beyond you may have heard the term “attic rain.” It sounds strange — but it’s one of the most common winter moisture problems we see during home inspections in Alberta.

At Arrow Inspections, we regularly find attic rain in both older homes and brand-new builds. Left unaddressed, it can cause serious damage to insulation, framing, ceilings, and even lead to mold growth.

Here’s what every homeowner should know.

What Is Attic Rain?

Attic rain happens when warm, moist air from inside your home rises into a cold attic space, then condenses and freezes on the underside of the roof sheathing, nails, trusses, and ventilation components.

When the temperature rises — even slightly — that frost melts and “rains” back down into your attic. Over time, this moisture can soak insulation, stain ceilings, rot wood, and create ideal conditions for mold.

In Calgary’s long, cold winters, attic rain is extremely common.

Why Attic Rain Is So Common in Calgary & Alberta Homes

Attic rain occurs everywhere, but it is especially prevalent in southern Alberta because of:

  • Long freezing winters
  • Large temperature swings
  • Chinook weather patterns
  • Airtight modern construction
  • Heavy indoor humidity in winter

Even a well-built home can suffer from attic rain if airflow, insulation, or air sealing is not properly balanced.

Signs of Attic Rain in Your Home

Most homeowners never go into their attic — which means attic rain can go unnoticed for years. Warning signs include:

  • Water stains on ceilings or drywall
  • Wet or matted attic insulation
  • Frost on nails, trusses, or roof decking
  • Mold or musty odors
  • Peeling paint or ceiling bubbles
  • Rusted attic fasteners

If you’ve noticed any of these, it’s time to have your attic inspected.

What Causes Attic Rain?

Attic rain is usually caused by a combination of:

1. Air Leaks from the Home Below

Warm air escapes into the attic through:

  • Bathroom and kitchen fans
  • Pot lights
  • Attic hatches
  • Plumbing and electrical penetrations

2. Inadequate Ventilation

Without proper intake and exhaust ventilation, moisture becomes trapped and freezes.

3. Improper Insulation

Compressed or missing insulation allows heat to escape and increases condensation risk.

4. High Indoor Humidity

Long showers, humidifiers, cooking, and unvented fans can overload the attic with moisture. (Pssst… run your fan for an hour after every shower!)

Why Attic Rain Is a Serious Issue

If ignored, attic rain can lead to:

  • Mold growth
  • Structural wood rot
  • Roof sheathing deterioration
  • Ceiling damage and drywall staining
  • Reduced insulation performance
  • Costly repairs

We often see thousands of dollars in damage caused by attic rain — especially in newer homes as they are built so air tight!

How Arrow Inspections Helps Identify Attic Rain

During our attic inspections, we:

  • Inspect roof sheathing and trusses for moisture and frost damage
  • Check insulation levels and condition
  • Identify air leakage points
  • Assess ventilation design and airflow
  • Look for mold or microbial growth
  • Provide clear photos and recommendations

We don’t just tell you there’s a problem — we explain why it’s happening and how to fix it.

Can Attic Rain Be Prevented?

Yes. In most cases, attic rain can be reduced or eliminated by:

  • Sealing air leaks
  • Improving ventilation balance
  • Adding or correcting insulation
  • Using bath and kitchen fans properly
  • Managing indoor humidity

A professional inspection is the first step to stopping attic rain before it causes permanent damage.

Book an Inspection in Calgary & Surrounding Areas

If you’re in Calgary, Airdrie, Cochrane, Didsbury, Olds, Carstairs, Sundre, Cremona, or Mountain View County, Arrow Inspections is here to help. Click Here for a Full List of Areas We Serve

We specialize in:

  • Attic inspections
  • Moisture and mold detection
  • New home and one-year warranty inspections
  • Rural and acreage properties

Don’t wait until water stains appear.

Attic rain is often happening long before you can see it.

Concerned specifically about mold? We do mold inspections and testing as well- Click Here for more info on mold testing.

👉 Book your inspection with Arrow Inspections today. Schedule Here

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