B.C. roofing advice

Why skylights leak and how roofers diagnose them

Skylights leak from the unit, curb, flashing, surrounding roof or condensation. Diagnosis should identify which part failed before sealant or replacement is proposed.

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Answer first

Compare weather timing

Wind-driven rain, snowmelt and indoor condensation create different patterns. The comparison should also account for unit age and seal condition and curb height.

How to evaluate the question

Each checkpoint tests a different part of skylight leak diagnosis against property evidence and the proposed scope.

Compare weather timing

Wind-driven rain, snowmelt and indoor condensation create different patterns; photographs, measurements or records should confirm unit age and seal condition.

Inspect the full flashing sequence

Head, side and sill details must connect to the roof and underlayment in the correct order; the written conclusion should show the effect of curb height on the result.

Assess the unit itself

Failed glazing seals, frames or drainage channels may require skylight replacement rather than roof patching; recheck flashing sequence when the condition, scope or timing changes.

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Property-specific inputs

What can change the general answer

  • Unit age and seal condition: Record unit age and seal condition with measurements, photographs or dated notes before drawing a conclusion about skylight leak diagnosis.
  • Curb height: Compare how each option handles curb height; the difference may change cost, timing or risk.
  • Flashing sequence: State assumptions about flashing sequence explicitly so they are not mistaken for verified site conditions.
  • Roof slope: Connect roof slope to the roof area, assembly or responsibility it affects.
  • Interior humidity: Recheck interior humidity when the property condition, proposed scope or schedule changes.

For the skylight leak diagnosis, keep measurements, observations and assumptions separate. During the review of the skylight leak diagnosis, any input that cannot be verified safely should remain conditional until a site review or controlled opening provides evidence.

A practical comparison

Use the table to organize the conditions, responsibilities and next actions that affect skylight leak diagnosis.

SymptomPossible sourceNext check
Leak in windSide or head flashingDirection and laps
Fog between panesGlazing sealUnit replacement
Interior surface moistureCondensationHumidity and ventilation

Turn the guidance into a property decision

In the written record for the skylight leak diagnosis, a documented next step is more useful than a universal answer detached from the roof.

Confirm the starting information

Gather the address, building type, roof system, known age, repair history and records related to unit age and seal condition.

Review the condition safely

Use safe photographs, inspection notes and measurements to assess curb height without asking an owner to climb onto the roof.

Compare complete options

Check how each option treats flashing sequence, roof slope and any concealed condition that could change the scope.

Record the next decision

Write down the chosen action, assumptions, timing and the evidence still needed about interior humidity.

Technical context: Decisions about skylight leak diagnosis should be checked against current product instructions, the approved project scope and applicable British Columbia building and workplace-safety requirements. General guidance never makes unsafe roof access appropriate.

Frequently asked questions

These direct answers address the property details most likely to change a decision about skylight leak diagnosis.

Can skylight sealant stop a leak?

It may temporarily cover a small joint, but it does not correct missing or reversed flashing. Durable work rebuilds the water path.

Can a skylight be replaced without a new roof?

Often, if surrounding material remains flexible and can be re-integrated. Brittle roofs may require a larger work area.

Why does the leak appear in winter?

Snow buildup, ice, condensation or freeze-thaw movement may create a seasonal path. The interior and exterior evidence need to be compared.

Apply the guidance to the property

Before approving the skylight leak diagnosis, send the address, building type, known roof system, safe photographs and timing. Roofing Star can compare the guidance on skylight leak diagnosis with the property condition and explain whether an inspection, estimate or maintenance plan is the right next step.

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