Foundations fail quietly at first. Hairline fissures bloom behind a couch, a door needs an extra nudge to latch, floors develop a barely perceptible slope. Most owners ignore these early signals, and I understand why. Houses move, seasons change, and it’s easy to chalk it up to “settling.” After a couple of decades crawling under homes and measuring slabs, I’ve learned that patterns, not single symptoms, tell the story. A solid foundation inspection looks for those patterns in a methodical way, then weighs risk against cost. When you do that well, you avoid panic repairs, and you don’t miss the moment when timely foundation repair will save you money and preserve your home’s value.
This guide lays out how to inspect a foundation like a pro, what matters more than it seems, and when to escalate to foundation repair, foundation leveling, or soil stabilization services. I’ll also share the judgment calls I make in the field, including the gray areas where two inspectors might disagree.
Start with the site, not the cracks
Every foundation sits in a relationship with water and soil. If you skip the site conditions, you’re inspecting half a system. Walk the property after a rain if you can. I look for overland flow paths, spongy lawn sections near the house, and erosion scars. Downspouts that discharge near the foundation, negative grading that slopes toward the walls, and irrigation heads that mist the siding are repeat offenders. If you fix the foundation without addressing these, you’re setting up the same failure to repeat.
Clay soils shrink and swell as moisture changes. In parts of Texas, Colorado, and the Midwest, the expansion pressure can lift slabs several inches over a season. Sands behave differently, usually more stable but susceptible to washouts where water concentrates. If you don’t know your soil type, your county extension or a local geotechnical firm can tell you. The foundation’s performance profile should match its soil reality. A slab with seasonal high spots near moisture sources suggests expansive clay at work, while angular settlement at a corner often points to erosion or inadequate support under that segment.
The interior tour: small clues add up
I start indoors because it reveals how the structure is reacting. A laser level or water level is useful, but your senses are still the best first tools. Two or three degrees of tilt rarely shows visibly, yet your feet will feel it on long runs.
Doors tell the truth. A door out of square at the top latch side, consistent across several rooms along one exterior wall, often means that section of the foundation has dropped. If a few interior doors stick while others swing freely, map their locations. Patterns matter more than individual complaints.
Drywall cracks alone aren’t decisive. Vertical or diagonal fissures above doorways and at window corners are common. I note width and whether the edges are clean or packed with paint, which hints at age. A fresh crack with sharp edges and an exposed gypsum core is new movement. Step cracks in interior masonry, or a horizontal crack running along a mid-wall plane, raise the stakes.
Floors tell an honest story with a marble, but I prefer a 6-foot level and a little patience. Measure from the center of rooms to exterior walls and toward known heavy loads like a masonry fireplace. Normal residential tolerance allows about 1 inch of variation over 20 feet, though older homes often drift beyond that without distress. I flag abrupt changes rather than gentle slopes. A 3/8-inch ridge over 6 feet usually indicates a hinge line in the structure.
If there’s a crawlspace, I push to get underneath before making any conclusions. Wood posts on bare soil, shims stacked like Jenga, or beams not bearing fully on piers are common culprits for sloping floors that get incorrectly blamed on the foundation.
Exterior walls, windows, and the shape of distress
Outside, masonry tells the clearest story. Step cracking in brick or block near corners, especially if the mortar joints widen as they climb, often means settlement at that corner. Long horizontal cracks mid-course are more serious and could indicate lateral soil pressure or shearing. A single hairline diagonal crack in stucco can be cosmetic, but parallel cracks forming a V-shape across a wall, widened at the top or bottom, suggest racking from uneven movement.
I look closely at window and door lintels. Rust jacking, where steel angles expand as they corrode, can mimic structural movement. A rusty lintel that swells and warps will crack bricks above it even if the foundation is stable. Fixing that requires addressing the lintel, not the foundation.
Measure expansion joint gaps if the building has them. A widened joint can indicate global shrinkage in masonry rather than foundation settlement. If one joint opens while another compresses, the structure is moving in a specific direction, which helps identify the zone of trouble.
The slab and perimeter: subtle signs, firm evidence
On a slab-on-grade home, perimeter inspection is critical. I probe with a screwdriver at the bottom course where possible to check for wood rot or termite tubes. Spalling concrete near grade can result from de-icing salts or poor mix, not necessarily movement. I inspect any exposed slab edges for vertical displacement across control joints. A clean offset greater than 1/8 inch along a slab crack suggests differential settlement rather than simple shrinkage.
If the foundation has stem walls, I check for bowing, horizontal cracks, or efflorescence. Efflorescence alone is not a structural concern, but its presence maps moisture paths. Tie that back to gutters, grading, or irrigation.
In a crawlspace, I carry a bright flashlight and a moisture meter. Standing water or saturated soil after a week without rain points to plumbing leaks or groundwater intrusion. I run a straightedge along beams and note depressions or crown. If wood posts sit directly on soil, I expect some settlement. Concrete or masonry piers should have full bearing and intact mortar. Split shims and small air gaps are common indicators of minor creep that a carpenter can correct without calling a foundation repair crew.
Drainage and plumbing: the hidden players
Most foundation problems have a water story. I verify that downspouts carry water at least 5 to 10 feet from the house. I look for the telltale burn of gutter overflow on the ground below a seam. Landscaping mounds against the siding are a recurring issue. Raised beds trap moisture and flatten the grade that should slope away 5 percent or more for the first 10 feet.
In slab houses, plumbing leaks can undermine soils. If the home shows signs of unexplained settlement in a single zone, I ask about water bills and consider hydrostatic testing of lines under the slab. It is intrusive and not the first move, but in the right circumstances it saves an owner thousands by preventing misdirected repairs.
A practical field checklist you can reuse
Use this compact checklist during your walk-through. It’s not a substitute for judgment, but it keeps the process orderly.
- Site drainage: roof runoff, downspout discharge distance, yard slope, irrigation spray near foundation Exterior: masonry cracks and patterns, lintel condition, expansion joints, slab edge offsets Interior: door and window operation, drywall cracks, floor level changes, fireplace and chimney plumb Crawlspace or basement: moisture, standing water, pier and beam condition, shims and bearing, wood rot or termites Utilities: signs of plumbing leaks, high water bills, sump pump performance, efflorescence mapping
Sorting cosmetic from structural
Not every crack deserves a crew. Shrinkage cracks in slabs, usually thin and relatively straight, appear within the first year. Hairline stucco crazing looks like a spider web and rarely signals structural trouble. Repeated paint bridging over the same drywall crack every season, however, often means ongoing movement.
Width matters, but rate of change matters more. A quarter-inch crack that appeared over a decade may be benign. A sixteenth-inch crack that doubled in a month is a red flag. I often tape a dated crack monitor or even a simple piece of glass across a crack with epoxy. If it breaks or the gap changes measurably in a few weeks, I know movement is active.
Uneven floors with no corresponding wall distress can be a floor system issue, not a foundation failure. I’ve shimmed beams and adjusted posts to straighten floors without touching the foundation. Conversely, a house can have flat floors and still suffer foundation movement that only shows in masonry and window operation. This is why patterns across multiple elements matter.
When to call for foundation repair
Three situations consistently warrant a qualified assessment for foundation repair.
First, progressive movement with clear patterns. Examples include widening stair-step cracks in brick near corners, doors going out of square across an entire wall line, and measurable changes in floor elevation over months rather than years.
Second, structural red flags. Horizontal cracks in basement walls, bowing stem walls, rotating masonry at corners, and significant offsets at slab cracks. Chimneys pulling away from the house more than a half inch, or with a visible lean, also fall here. These conditions can escalate quickly and affect safety.
Third, water-driven failures that exceed simple drainage fixes. If you’ve corrected grading and downspouts yet still see heave or settlement localized near plumbing routes, it’s time to investigate below the slab and consider intervention.
Owners sometimes wait for a perfect diagnosis before moving forward. The reality is that soils and structures are complex systems with uncertainty. A good repair plan addresses the most probable cause, reduces risk, and integrates prevention, especially drainage control.
What foundation repair or foundation leveling looks like in practice
Terminology varies by region, but the goals stay consistent: stabilize movement, recover lost elevation where feasible, and prevent recurrence.
Underpinning with piers is common for settlement. Steel push piers or helical piers transfer the load to deeper, more stable soils or bedrock. I favor hydraulically driven steel piers in areas with known strata at predictable depths, and helical piers where lift control and torque feedback offer better confirmation of capacity. Typical pier spacing runs 5 to 8 feet, adjusted for loads and soil. Lift is controlled and measured, targeting a return to near-original elevation without over-stressing finishes.
Slab jacking, also called pressure grouting or polyurethane foam injection, fills voids and lifts settled slab sections. It suits interior slabs, garages, and flatwork. For structural slabs tied to walls, I use it cautiously, usually as a void fill after underpinning has arrested settlement. Foam reacts fast and is clean, cement grout allows more gradual control. Each has a place.
For crawlspace homes, girder reinforcement and new interior piers can address sag without touching the perimeter foundation. I insist on proper footings under new posts and pressure-treated materials. Temporary jacks used as permanent supports are an invitation to future problems.
Heave from expansive clays calls for a different approach. Pure lift is not the answer. The playbook shifts to moisture management, soil stabilization services, and sometimes structural isolation measures like void forms or moisture barriers. Chemical soil stabilization, using lime or other agents, can reduce swell potential in specific contexts, mainly during new construction or major reconstructions. In existing homes, targeted injections to densify or alter soil behavior are possible but must be designed and tested, not guessed at.
Drainage corrections: the cheapest, highest-return fixes
I have lost count of how many “foundation repair jobs” were solved by moving water. Extending downspouts with rigid piping to daylight, adding surface swales that quietly redirect stormwater, and regrading a few inches over the first 8 to 10 feet around the house can halt active movement. In expansive soil regions, consistent moisture is key. That does not mean watering the foundation indiscriminately. It means controlling irrigation so the soil along the perimeter neither dries out to a crust nor turns to mud. Drip systems with moisture sensors do better than spray heads.
French drains can help if groundwater is foundation leveling the driver, but a perforated pipe in a gravel trench without a clear discharge point is a money pit. Drains need slope, fabric-wrapped gravel, and an outlet. Sump systems work in basements and low yards when discharge is guaranteed away from the foundation and not into a neighbor’s yard, which can create new liabilities.
How to decide between monitor, maintain, or repair
When I deliver an inspection report, I break the decision into three tracks.
Monitor: Choose this when distress is minor, stable, and the site risks are manageable. I recommend documenting elevations at a few consistent interior points every 6 to 12 months, photographing key cracks with a ruler for scale, and maintaining drainage. If nothing changes materially, you’ve saved yourself unnecessary intervention.
Maintain: This is for cases where the root cause is evident and fixable without structural work. Examples include redirecting downspouts, regrading, repairing plumbing leaks, adding pier shims in a crawlspace with proper footings, or addressing rusted lintels. I sometimes pair this with short-term monitoring to confirm improvement.
Repair: Commit to foundation repair or foundation leveling when movement is active, patterns are clear, and non-structural fixes cannot mitigate the issue. Prioritize structural integrity first, aesthetics second. An honest contractor will explain what recovery is realistic. Full restoration to millimeter-flat floors is rarely practical in older houses and can cause collateral damage to finishes. The right endpoint is a stable, serviceable structure with moisture managed and future risk reduced.
Cost ranges and what drives them
Prices vary widely by region, soil, access, and scope. As a rough guide, underpinning a small section with a handful of piers might start in the mid four figures. Full perimeters on a typical single-story home can climb into the mid to high five figures, especially on complex footprints or limited access sites. Slab jacking for a garage slab might be in the low to mid four figures, more if deep voids exist. Drainage corrections range from a few hundred dollars for gutter work to several thousand for regrading and piping.
What drives cost more than anything is uncertainty and access. Confined crawlspaces, heavy landscaping, and tight lot lines add labor. Uncertain soil behavior demands more testing and contingency. This is where soil stabilization services can be cost effective, especially when planned alongside structural measures to reduce long-term risk.
Choosing a contractor without regret
I vet foundation contractors the same way I vet surgeons. Tools and trucks matter less than method and transparency. Look for clear load path explanations, not just pier counts. Ask how they determine pier spacing, how they measure lift, and what refusal criteria they use on driven piers. Good firms will talk about torque values for helicals, recovery targets, and how they’ll protect finishes during lift.
Beware of one-size-fits-all prescriptions. If every problem looks like a pier to the salesperson, keep looking. Independent engineering input can be worth the fee, especially on high-value properties or ambiguous cases. Some regions allow contractors to design their own solutions. That can work, but only if they show their calculations and assumptions. Warranties are only as strong as the company behind them. Transferable warranties with clear service terms have real value, but they aren’t a substitute for sound design.
Regional nuances and special cases
Mountainous areas with frost cycles see different stress patterns than coastal sands. Frost heave can mimic expansive clay heave, but the cure emphasizes insulation, frost-protected shallow foundations, and drainage that prevents saturation before deep freezes. In coastal zones, scour from stormwater and poor compaction under slabs show up as voids more than global settlement. Infill urban lots often sit on varied fill soils; here, preconstruction records and test pits can be invaluable.
For historic homes, preservation matters. Mortar repairs should match composition and compressive strength, not just color. Overly hard Portland cement mortars on soft historic brick cause damage that looks like settlement. I’ve seen owners chase foundation work when the fix was simply proper repointing with lime mortar and gentle drainage improvement.
Manufactured homes and pier-and-beam houses share an Achilles heel: supports on soil without adequate footings. Seasonal creep in soft soils becomes cumulative. The right fix is larger, deeper, and properly reinforced footings, not just more shims.
Common mistakes to avoid
- Treating symptoms: Caulking cracks and planing doors without addressing drainage or structural movement is a short-term patch that hides trendlines you need to monitor. Overlifting: Chasing perfect level can crack tile, pop drywall, and stress framing. Controlled lift to stabilize and improve is smarter than maximal lift. Ignoring plumbing: Especially on slabs, unaddressed leaks will defeat even excellent underpinning. DIY grading gone wrong: Piling soil against siding or burying weep holes traps moisture and creates rot. Procrastinating on red flags: Bowing basement walls and widening horizontal cracks demand fast attention. Waiting multiplies cost and risk.
Maintenance that actually helps
Homeowners often ask how to “take care” of a foundation. The most practical maintenance involves water control and observation. Keep gutters clear and extensions intact. Verify that soil slopes away at a steady 5 percent. Set sprinklers to water plants, not the wall. In clay regions, consider a perimeter drip with moisture sensors to smooth out extremes, especially through hot-dry and wet-wet swings.
Inside, adjust expectations. Houses move a little. Seasonal hairlines that open and close may not require intervention. When you do patch, use flexible foundation repair contractors compounds where movement is expected so you can track new activity rather than hiding it entirely. Keep a simple elevation map. A handful of measurements taken the same way each year is worth more than a high-tech survey done once and forgotten.
How soil stabilization services fit into the plan
Soil stabilization isn’t just for highways. On residential properties, it has two primary roles: reduce swelling potential in clays and improve bearing capacity in loose or fill soils. Techniques range from lime injection in clays to cementitious grouting that densifies zones under slabs or footings. Success hinges on testing. I want a soils report, Atterberg limits for clays, and a clear target outcome. Done thoughtfully, stabilization can shrink pier counts, reduce future heave, and partner well with drainage improvements. Done blindly, it’s money in the ground with little to show.
A final word on judgment
Foundation inspections reward patience and pattern recognition. If you chase every crack, you’ll overspend. If you dismiss every symptom as “settling,” you’ll miss the window for a cost-effective fix. Let the site tell you about water. Let the walls and floors tell you how the structure is reacting. Tie those stories together, and the decision to monitor, maintain, or move forward with foundation repair becomes straightforward.
The best outcome is usually a mix: tighten up drainage, correct local issues, and stabilize structurally where the patterns justify it. That combined approach protects your investment, makes the house feel right underfoot, and keeps you from revisiting the same problem in five years. When in doubt, get a second set of eyes, preferably from someone who can explain the soil-structure-water relationship in plain language. The truth of a foundation lives in that triangle.