Follow rain away from your foundation

Start at the roof and work outward

Rain landing on a roof concentrates at gutters and downspouts. Where that discharge lands affects how much water reaches the foundation area. Surface grading then directs water toward or away from the house, while soil conditions, paving and subsurface drainage affect what happens below ground.

Look from accessible ground for disconnected downspouts, overflow marks, ponding and low areas beside the house. Note whether the condition appears during heavy rain, prolonged rain or snowmelt. Do not climb onto a roof or enter an excavation for these observations.

Numbers identify the parts explained below.

Site conditionsBuilding responseSpecific evidence

Learning illustration • see the labels and limits below.

The explanations below remain available as you explore.

1. Weather-facing roof

   Observe safely from accessible ground; do not infer a cause from one mark.

2. Room equipment

   Confirm what the device does and the scope of its performance information.

3. Ground connection

   Site and buried conditions differ from the visible room.

What does this illustration leave out?

Exposure, airflow, filtration, moisture, foundation condition and parcel risk require specific evidence. This illustration explains an idea. It is not an installation guide.

A BETTER QUESTION

How do I separate observations about the room, equipment and site before choosing a specialist scope?

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Grade is a ratio

Slope equals vertical change divided by horizontal distance. Use matching units, then multiply by 100 to express a percentage. A drop of 7.5 cm over a horizontal run of 1.5 m corresponds to 5%. The calculator lets you explore that geometry; it cannot determine property boundaries, acceptable discharge points or a drainage design.

Government of Canada guidance describes 5% as ideal and 2% as a commonly considered minimum in relevant situations, with different considerations for paving. Local rules, site constraints, nearby properties and foundation clearances govern actual work. A generic target should not become a reason to pile soil against siding or move water onto a neighbour.

Below ground adds uncertainty

Surface observations do not show the condition of foundation waterproofing, weeping tile or a sump system. A damp wall after rainfall is evidence of timing, not proof of the failure point. Water may travel through cracks, penetrations, joints or porous materials, and more than one mechanism can occur together.

A professional can compare inside and outside elevations, inspect accessible drainage equipment and investigate likely entry paths. Foundation movement or structural cracking needs qualified assessment. Do not seal over a recurring symptom and assume the underlying moisture problem has ended.

Document a storm without increasing risk

Photograph pooling from a safe dry position, note rainfall timing and record which interior locations become wet first. Mark the extent of dampness and whether it returns after repairs. In multi-unit or shared drainage settings, involve the responsible owner or manager.

Avoid wet electrical equipment, unstable excavations and sewage-contaminated water. If there is immediate flooding or structural concern, stay clear and arrange appropriate help. A useful handoff includes the pattern, not a confident unverified diagnosis.

Distinguish routing from waterproofing

Roof water, surface runoff and below-ground water can reach different parts of the home. A downspout that sheds water into a low area and a failed below-ground system are not interchangeable diagnoses. The useful first map shows collection points, discharge locations, pooling and the timing of interior evidence. Observe only from safe accessible ground.

Surface geometry can change after soil settles or landscaping changes. The slope calculator describes an entered drop and run; it does not account for the complete catchment, soil response, neighbouring property or discharge restrictions. A steep line drawn on a diagram can still direct water to the wrong destination. Route and receiving condition matter as well as the ratio.

Crack width, orientation, movement history and water timing are inputs to a qualified assessment. A single photograph cannot establish structural significance, and an apparent cosmetic repair cannot establish that movement stopped. Ask whether the professional is investigating water entry, structural movement or both, and what evidence would distinguish them.

Build a weather-linked evidence record

Use dated photographs from the same accessible viewpoints and note rain, snowmelt and recent site work. Mark the affected interior location without assuming it lies directly beneath the source. Water can travel through assemblies before it becomes visible. Do not enter contaminated or electrically hazardous areas to complete a record.

For a buyer, ask for previous water-event and repair records and the limitations of the inspection conditions. A dry showing is not a storm test. For a seller, describe completed drainage work with its actual scope and keep follow-up records. A specialist should explain what was addressed and what remains unverified, rather than promising that every future storm has been eliminated.

A slope measurement describes geometry, not the whole catchment

A measured drop divided by its horizontal run describes one line. With a fictional 100 mm drop over 2,000 mm, that line has a 5% slope. The arithmetic establishes neither a locally required slope nor a complete drainage design. It omits the area contributing water, receiving route, surface changes and below-ground response. A correct percentage can still describe a route toward an unsuitable destination.

Observe where roof discharge, hard surfaces and ground appear to collect or release water from safe ground. Keep the timing of rain, snowmelt and interior dampness with those observations. Delayed indoor evidence does not establish a single buried cause, while water visible immediately after a storm does not prove it entered at the nearest exterior puddle.

Ask a qualified professional which parts of the route are confirmed and which need records or further investigation. A site-water assessment, foundation moisture review and sewer investigation may answer different questions. Protective plumbing also has its own route limits. A backwater device or sump cannot be assumed to resolve every wall, window-well or surface-water concern.

Numbers identify the parts explained below.

Roof water arrivesGround levels guide itCheck where it goes

Learning illustration • see the labels and limits below.

The explanations below remain available as you explore.

1. Grass and ground

   Grass is the yard’s surface finish; the levels beneath it influence where surface water goes. From safe, ordinary access, note ponding or water near the house and ask how the actual grading carries it onward. A green lawn alone does not answer that question.

2. Bare-soil area

   An unfinished or altered area can change the question about final ground levels. Ask what work remains, whether the grading file matches the present yard, and whether later landscaping changed it. The pictured patch has no recorded construction history.

3. Downspout and splash block

   The downspout carries roof water down; the block receives it at ground level. Then the rest of the yard must take it somewhere appropriate. Follow that next question in the actual drainage plan; the illustration does not show a complete discharge design.

What does this illustration leave out?

The scene supplies no crack measurements, movement history, surveyed ground levels or observed water flow. It cannot identify the cause of a real crack or establish structural condition. Local grading requirements and any repair need a property-specific assessment. This illustration explains an idea. It is not an installation guide.

A BETTER QUESTION

After water leaves this home’s downspout, where does it go, and do the present ground levels match the drainage plan?

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Work through a fictional low-area and delayed dampness record

A fictional owner measures a sloping line beside the house, photographs pooling beyond its end, and notices basement dampness the following day. An old invoice says downspout extended. These records support a route question and a chronology, but do not establish foundation-drain failure or prove that the extension caused the present pattern. The invoice's exact discharge scope remains relevant.

The owner asks a site or building professional to assess the reported water pattern and define any complementary plumbing or structural question. They do not excavate, redirect water onto adjoining land or treat a single crack photograph as a structural finding. The report should explain methods, observations and exclusions, including the weather conditions actually assessed.

Suppose a receiving-area concern is identified but below-ground conditions remain outside the assignment. Preserve both facts. A scoped improvement can be discussed without claiming that every storm or source has been eliminated. Follow-up observations under their actual conditions help evaluate the intervention while acknowledging that a quiet weather period is not a demanding event test.

Go to the source.

Original HomeAI explanation informed by these public references. Sources support the underlying guidance; they have not reviewed or endorsed HomeAI. Diagrams are conceptual, and calculator outputs depend on your inputs.

• Government of Canada · Property grading
• Natural Resources Canada · How your house works
• City of Ottawa · Preventing basement flooding
• City of Ottawa · Protective-plumbing questions
• City of Calgary · Flood readiness