Why Does My Roof Leak in the Winter?

The winter brings us holidays, lights, eggnog, and general good cheer, but unfortunately, it can sometimes cause dark circles to suddenly appear on our ceilings. Maybe it was a dry winter, hasn’t snowed much at all. Then, what are these phantom circles? Excellent question. 

The Most Common Causes Of Leaky Roofs In Winter  

1. Roof Vents Without a Filter

Roof vents that are designed without filters can end up letting fine, wind-driven snow blow into your attic. This snow piles up, and while it remains cold outside you won’t notice. However, when it begins to warm up, and the temperatures get above freezing, the snow is going to begin to melt. Now that moisture may start to drip and stain your ceiling. 

The liquid eventually evaporates, sometimes leaving a permanent stain. Sometimes the water spots will disappear and may be gone for several years until the exact same conditions occur again.

Solution: Stop by the store. Hardware stores sell a commercial filter that will come in a roll. The filter is usually blue and about 1″ thick. It can be cut with scissors and friction fit into the bottom of the vent, or if you can, around the upright portion of the vent. The filter blocks the snow but allows the air to flow freely.

Lincoln roof repair

Stains around vent show where water has been leaking in.

2. Condensation On Pipes That Vent Through The Attic

Heating or furnace pipes are warm and carry hot, moist air right up through the house. The heated air rises and collects in the cap. Then, it sometimes runs back into the double-wall pipe. The water is trapped within the double wall until it finds an escape. Usually, this is at a bend, or elbow, in the pipe. The water then drips into the attic and onto your ceiling. 

Solution: I learned this from a friend of mine that works in heating and cooling, is to remove the cap and seal the top of the double wall pipe with a high-heat silicone or urethane sealant. Then, re-install the cap. The sealant keeps the water from getting into the wall of the pipe—simple!

Lincoln roof repair

Lincoln roof repair

3. Bath Vent Transfers Warm, Damp, Heated Air Into The Attic

This can result in several problems. Too much moisture in the attic can cause the roof sheeting to swell and buckle, which is an expensive fix. A damp attic combined with poor ventilation can cause mold build-up, which can become a health problem as well. 

Solution: is to make sure that the vents extend through the roof and have a backflow flap. The pipe should be insulated to keep condensation from forming. Also, make sure the attic is properly ventilated.

Lincoln roof repain

Noninsulated bath vent pipe.

Lincoln roofing

New, insulated vent pipe.

 4. Ice Dams

Ice dams are formed when the temperature outside warms to above freezing during the day, melting snow, and then re-freezes overnight. This occurs on the cool part of the eave or the non-heated surface of the roof. Then, this cycle of thaw and re-freeze continues until the ice forms so thick that it causes water to dam and run backward underneath shingles. In addition to having water running back into your house, causing roof leaks, ice dams can also rip of gutters and loosen shingles.

Solution: If the dam already exists, your best bet is to purchase some calcium chloride and pour it into tube socks or pantyhose, laying them vertically across the dam and hanging slightly over the roof. This should slowly melt the ice and create a groove for the water to escape without coming back into the house. Prevention will be a bit more intensive as you may need to add insulation, seal any airflow leaks, or add vents to keep it cool.

Be Cautious

Depending on the height and pitch of your roof, you might want to avoid any DIY and simply hire a roofing professional. And that is where Carlson Projects Inc. comes in! When it comes to Lincoln, NE roofing, we are your experts. Whether you’re looking for a new roof, a roof repair, or wondering how to install a roof vent, we love what we do and we’re ready to help!

Contact your Lincoln roofing and roof repair scholars for your free quote today!

And while you’re here, check out our roofing blogs When Hail Falls, You Know Who to Call! and A Roof Leak That May Not Be Your Roof.




  1. anita Johnson

    We some some help we have a 20 foot ceiling and the snow once it melts goes through the ceiling and makes a big mess.

    • Stefan Carlson

      Give us a call we’d love to help, 402-420-5808.

  2. kurt goncher

    I see this was an old blog, about the time my house was built, but now had a snow storm that blew in snow through our roof vents, and is dripping into multiple rooms from vents. You mention a filter material to add but no name.. I went to the Home Depot but no such filter , what is it called and who sells it?
    “Simple solution, the hardware stores sell a commercial filter that will come in a roll, Usually Blue and about 1″ thick.”