Why Does Snow on a Roof Cause Water Leaks?

When snow accumulates on a roof, heat from the attic warms the underside, melting the bottom layer of snow. That meltwater runs down the slope until it hits the colder eaves, where it refreezes. Over time, this creates an ice dam, a ridge of ice at the roof edge.

As the ice dam grows, it traps meltwater behind it. The pooled water has nowhere to go but up and under the shingles. Once water gets beneath the roofing material, it can soak into the decking and insulation, eventually dripping into your living space. This is a common cause of winter ceiling stains.

• Look for large icicles at the roof edge
• Check for water stains on ceilings or walls
• Notice if snow melts unevenly across the roof
• Inspect attic insulation for dampness
• Clear gutters of leaves and debris before winter

Melting snow creates a steady flow of water that seeks the path of least resistance. If the roof has damaged flashing around chimneys, vents, or skylights, that water can easily penetrate. Even small gaps around pipe boots or valleys can become entry points.

Once water enters the roof assembly, it travels downward along rafters and through insulation. It may not appear in the room directly below the leak; it can travel horizontally and stain a wall or ceiling several feet away. This makes finding the source tricky.

• Check around chimneys and skylights
• Inspect attic for wet insulation
• Feel walls and ceilings for damp spots
• Look for peeling paint or bubbling wallpaper
• Listen for dripping sounds in walls

If you notice a leak during or after a snow event, it is wise to call the pros. They can assess the damage, extract standing water, and dry out affected areas using specialized equipment. They also help document the damage for your insurance claim, if you choose to file one.

Policies vary, and your insurer decides what is covered. So, check your policy and contact your insurance company to understand your coverage. The pros can guide you through the cleanup process, but they do not decide what is covered. Their focus is on restoring your home to a dry, safe condition.

For roof damage itself, you may need a roofing contractor to repair the source of the leak. The pros can handle the interior cleanup, while the roofer fixes the shingles or flashing. Both types of professionals play a role in protecting your home.

• Contact a roofer for shingle or flashing repairs
• Hire the pros for interior cleanup
• Use a dehumidifier to reduce moisture
• Remove wet carpets and padding
• Dispose of damaged drywall and insulation