Why Is My Skylight Leaking in Winter in Fargo?
A skylight that drips in winter usually has one of three problems: condensation forming on cold glass or framing, failed flashing around the curb, or meltwater from an ice dam backing up under the shingles. In Fargo and Moorhead, condensation is the most common cause and flashing is the most costly one to ignore. Dodd Roofing and Exteriors inspects skylights across the metro, and the first job is always sorting out which of the three you actually have.
How can I tell if my skylight is leaking or just sweating?
Timing and pattern tell you most of it. Condensation shows up on cold mornings, runs down the glass or the inside of the light shaft, and dries out by afternoon. A true leak shows up after snow melts, often a day or two after a warm spell, and leaves a brown stain that grows each time. Stains at the top corners point to flashing, while drips at the bottom of the frame often come from condensation running down the inside. If the drywall stays damp for days or the stain has a ring pattern, treat it as a leak. Our post on window condensation in Fargo winters explains the humidity side of the problem.
Why are Fargo winters so hard on skylights?
Fargo gets around 50 inches of snow in an average winter, and January lows sit near zero. A skylight is an opening in the warmest part of your roof, so the curb melts snow faster than the shingles around it. That meltwater runs down to the cold edge, refreezes, and works its way under the flashing. Skylights installed in the 1990s and 2000s in south Fargo, West Fargo, and Horace often still have original sealant that has dried and cracked after twenty or more freeze and thaw winters. Older homes in Hawthorne and Roosevelt more often have a skylight added later by a previous owner, and those retrofits are where flashing shortcuts show up most.
Which parts of a skylight fail first?
Four parts, in rough order: the sealant at the corners, the step flashing along the sides, the head flashing at the top, and the glass seal itself. Sealant is a patch, not a fix, and it usually fails again within a couple of winters. Step flashing and head flashing need to be woven into the shingles, and when they were reused or installed without a small diverter roof above the skylight, snow piles up behind the top edge and the water has nowhere to go. A foggy space between the panes means the glass seal has failed, which is a separate problem from a leak but a sign the unit is aging. Flashing behaves the same way at chimneys and walls, which we cover in our guide to roof flashing leaks in Fargo.
Can a skylight leak be repaired without replacing the roof?
Often yes. If the glass and frame are sound, a roofer can remove the shingles around the unit, install a new flashing kit made for your skylight model, and rebuild the shingle courses back to the curb. That is a roof repair job measured in hours, not a reroof. Replace the whole skylight when the glass is fogged, the frame is cracked, or flashing kits for that model are no longer made. If your roof is already near the end of its life, doing the skylight during a replacement is the more economical path, because the flashing gets brand new shingles around it instead of being matched to old ones.
Does homeowners insurance cover a leaking skylight?
Policies in North Dakota and Minnesota generally cover sudden damage, like a hail strike that cracks the glass or wind that lifts the flashing. They generally exclude wear and tear and slow leaks from aged sealant. Interior water damage may be covered when the cause is a covered event, and it often is not when the cause is a long term leak. Photograph the stain, note the date, and call your agent promptly. Do not cut into the drywall or paint over the stain before it is documented, and check your declarations page for any wind and hail deductible that applies.
What should I do about my skylight before the next freeze?
Start on the attic side, which is dry and safe in October. Look for dark staining on the wood around the light shaft, damp insulation, or daylight at the corners. From the ground, check for lifted shingles or gaps at the flashing, and clear snow near the skylight with a roof rake rather than a shovel, which can tear the flashing. Book repairs before the ground freezes, since flashing and shingle work goes best on days above about 40 degrees. Dodd Roofing and Exteriors offers free inspections across Fargo, West Fargo, Horace, and Moorhead. Browse our homeowner guide library for more winter prep help, or call (701) 831-0710 to get on the fall schedule.
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