Problem reference / concrete and masonry
What does a foundation crack establish?
A crack establishes that a material separated. It does not, by itself, establish why it happened, whether movement continues, whether water is entering, or which repair belongs there.
Assembly
Record whether the crack crosses poured concrete, concrete masonry, mortar joints, stone, brick, a slab, or more than one material. Different assemblies transfer load and movement differently.
Geometry
Map the direction, length, branching, location, and whether the faces are offset. A pattern is useful evidence, but it is not a cause by itself.
Change
Use dated photographs and repeatable measurements to record whether the crack is stable, seasonal, or changing. A single visit shows the present condition, not its history.
Companion evidence
Note water staining, efflorescence, bowing, floor slope, opening distortion, loose masonry, prior patches, drainage, nearby excavation, and damaged finishes.
Field record
Evidence to gather before discussing a fix.
Crack direction can guide the inspection, but the repair decision depends on the surrounding system and the intended outcome.
- 01
Expose and locate the condition
Record the room, elevation, wall or slab face, nearby corners and openings, and whether finishes hide the other side. Do not remove structural material to investigate without an appropriate plan.
- 02
Map the full pattern
Photograph the crack with a scale, mark its endpoints, and note branching, offset, bulging, open joints, spalling, loose units, and previous patches.
- 03
Establish whether it changes
Compare dated records when available. If monitoring is appropriate, state the reference points, interval, instrument, and limits of what the record can show.
- 04
Trace water separately
Check roof discharge, grading, drains, plumbing, groundwater observations, staining, salts, and the conditions under which leakage appears. A leaking crack and a moving crack are related questions, not interchangeable diagnoses.
- 05
Check the supporting system
Document footings, walls, columns, beams, framing, additions, settlement evidence, exterior soil pressure, and connections that can be seen. Hidden or mixed assemblies may require further evaluation.
- 06
Define the repair objective
Require the proposal to name the cause it is addressing, the preparation and material, how active movement or water will be handled, what remains visible, and the inspection, permit, warranty, and monitoring records included.
Water-path repair
Sealing a crack can address leakage without proving structural repair.
Injection, routing and sealing, drainage, and exterior water control serve different conditions. A scope should state whether the crack is expected to move and where water will go if the seal is bypassed.
Structural response
Movement may require work beyond the crack line.
Wall reinforcement, underpinning, rebuilding, or another structural repair changes the load path or support. Filling the visible line alone does not establish that the movement source was addressed.
Safety boundary
Keep people away when failure appears possible.
Sudden displacement, falling or loose masonry, a visibly unsupported element, or damaged gas or electrical service needs an immediate safety response. Leave the building when collapse appears possible and contact emergency services or the appropriate building professional. The cited FEMA checklist is event-safety guidance, not a classifier for ordinary residential cracks.
Regional application note / contractor-owned source
603 Basement Solutions publishes New Hampshire crack guidance.
603 Basement Solutions publishes a New Hampshire homeowner guide that distinguishes monitoring from inspection and discusses crack direction, growth, leakage, and companion symptoms. Those are contractor-published screening cues, not independent structural thresholds or a diagnosis for a particular house.
This Guide therefore uses 603 only to establish its local service context. The technical decision framework above comes from the independent sources below.
Read the 603 foundation crack guideContractor-owned source ↗Technical sources / checked September 11, 2026