Leaks only when rain blows from one direction

An intermittent leak is still worth investigating

Some homeowners describe a roof that is dry through several storms and then leaks during one particular combination of rain and wind. The absence of a symptom on other days does not invalidate that observation. It does mean that a simple inspection may not reproduce the circumstances, and the contractor should explain the limits of any conclusion reached on a calm, dry visit.

GAF identifies wind-driven rain as a possible route of water intrusion. That general mechanism does not identify the vulnerable detail on your house. The useful task is to connect the actual weather exposure, building geometry and observed defect. A written appraisal should distinguish “this could admit water” from “we have evidence this caused the reported leak.” Both statements can be useful if they are clearly labelled.

Describe the direction without inventing precision

Record which side of the house appeared most exposed and where you observed rain striking. If you use a weather service, keep its location and time with the report; a distant station is not a direct measurement at your roof. Your account can say “rain was striking the rear windows” without claiming a measured wind speed. Mark front, rear and side on a simple plan so different people use the same reference points.

Include a comparison event if possible: another storm with no visible change, or a previous leak under apparently similar exposure. These are observations for investigation, not a controlled experiment. Avoid drawing a conclusion from one event or assuming that a wind direction reported by an app exactly describes the local flow between neighbouring Toronto houses.

Map the symptom in three dimensions

Name the room, floor, wall and approximate stain position. State whether the water appeared on a ceiling, at a window head, down a wall or around a skylight shaft. Those distinctions help a professional decide which exterior interfaces deserve attention. Take an ordinary room photograph that includes recognizable corners, followed by a detailed view. A close-up without a location can easily become detached from the correct roof area.

If an addition meets the original house above that room, identify the junction in your notes. If a chimney or upper window is nearby, include it as context without declaring it responsible. On a semi-detached house, state which side you own and whether any proposed access or work could affect a shared boundary. Access consent and technical responsibility are separate questions.

Do not limit the investigation to the roof covering

A direction-sensitive symptom invites questions about exposed junctions and openings, but it should not become an excuse to seal every visible joint. Ask the investigator to consider whether the entry point could be associated with a wall, window, chimney or roof penetration and to explain the order of investigation. The report should name components rather than use “waterproofing” as a catch-all description.

If roofing and another trade overlap, ask who owns the diagnosis and who will coordinate the work. A roofer may identify a concern outside their proposed repair. That referral can be more useful than an unsupported promise to solve every possible source. A second opinion should receive the symptom history and labelled images, not merely the first quotation's total price.

What a useful inspection record contains

Ask for a written finding for each suspect area, supported by photographs showing its location and condition. The report should explain whether the area was directly accessible and whether inspection was visual only. If concealed layers or an inaccessible junction prevent a firm finding, request a next-step proposal with its own authorization and cost. You should not have to infer uncertainty from a long list of exclusions at the end.

Professional testing, if proposed, should have a defined purpose and stopping conditions. Ask what result would support the suspected source and what an inconclusive result would mean. This keeps testing from being treated as theatre: water seen indoors is not useful evidence unless the test sequence and area are documented. Homeowners should not imitate this work with a hose, ladder or attic entry.

Evaluate the proposed repair against the claimed mechanism

A strong proposal explains how the work addresses the identified route, what surrounding components must be disturbed, and how they will be reinstated. Ask whether the repair depends on existing adjacent materials remaining serviceable. If a broad replacement is recommended, request evidence showing why a local detail repair would be inadequate. The explanation should be specific to the inspected house, not simply that wind and rain are unpredictable.

Separate temporary protection from permanent correction and distinguish measured quantities from allowances. Obtain written approval terms for extra work. A discount offered only while the contractor is standing in the driveway does not improve the technical case. You can acknowledge a need to protect the home promptly while still requiring a clear scope and a documented decision.

Follow up under relevant conditions

A quiet week after repair is not the same as a test under comparable weather. Keep a simple log when similar exposure returns and note whether the original symptom changed. Do not assume a new mark in another room proves the previous repair failed; request a location-based comparison. Equally, a contractor should not dismiss recurrence at the same point without reviewing the original evidence and work record.

For AI-assisted review, ask for a table separating observed facts, professional interpretations and unanswered questions. Remove your address, signatures and personal identifiers before sharing. AI can notice that a proposal mentions a rear-wall detail while its photographs are labelled front roof. It cannot establish wind pressure, verify a concealed flashing or replace an on-site professional investigation.

Compare the evidence before deciding.