You look up one day and see water dripping inside your house. This is odd because it’s been chilly, but it hasn’t been raining. Plus, your roof is quite new and shouldn’t be letting any water in. If the air hasn’t been wet with precipitation…why do you see dripping? We’re here to tell you what’s probably happening.

In the northwest and in Bellingham, it’s easy to over ventilate your house. When it gets especially cold, too much ventilation can actually lead to ice on the underside of your roof that then drips water. How?

The roof itself can get very cold, even colder than the air around it. The air, relatively warm and wet, comes into the attic through vents and makes contact with the roof deck’s cold underside. Warm wet air can also enter the attic through holes in the ceiling, commonly at plumbing and electrical penetrations. This warm, wet air condenses and then freezes on the roof deck underside. As the day warms up, this frost melts and drips down. This is the dripping that you see from the living space below! It’s dangerous because with enough drips, mold and structural damage can occur, starting in your attic.

In this situation, you may even be able to see other problems occur first as a result of this condensing and freezing. The top 3 things other things to take notice of:

  1. Rusty nails coming through roof deck
  2. Staining from roof deck (This is generally black staining on the roofdeck, a sign of condensation.)
  3. Mold on the roof deck (Go to the attic and look up at the sloped area of the roof; this is where you’d see water, mold and/or rusting that result from condensation.)

Now that you know what other factors to look out for, let’s talk about how to fix this situation.

  1. Give us a ring and tell us what’s going on. “My roof is leaking, but it is not raining. Yes, it’s been really cold! We just put on a new roof, so it shouldn’t be the roof that’s leaking. I read this blog on roof deck freezing and think I’m having condensation problems on my roof deck”.
  2. You’re probably right! We’ll come see your roof in-person to make sure. Assuming that’s indeed what’s happening, we’ll suggest how to fix it.
  3. The ultimate solution is to seal the vents and add insulation on top of your rooftop to make it a “hot roof deck”. This insulation on the roof deck slope will warm the area and prevent the condensation from happening. Then, we’ll make it airtight, blocking off exterior vents to make sure attic space gets and stays warm. This is critical as we’ve just moved the heart of your insulation from the ceiling and added it to the roof deck. With these steps completed, your roof should be good to go!

In general, we can also reduce the amount of moisture resulting in condensation through proper ventilation. Read about our Home Ventilation Services to see why ventilation is important and how to prevent major issues with a few simple steps.