Structural defects can cost you tens of thousands in repairs—or worse, make a property unsafe to live in. Knowing what home inspectors look for separates buyers who catch expensive problems early from those who discover them after closing. Here's the concrete checklist professionals use to evaluate homes.
The Foundation: Where Problems Start
Your foundation carries the entire house. Inspectors examine it for cracks, settling, water intrusion, and structural movement that signals deeper issues.
Horizontal cracks (running side-to-side) are red flags—they indicate pressure pushing against the walls. Vertical cracks smaller than ⅛ inch are typically cosmetic, but anything wider warrants further investigation by a structural engineer. Expect to pay $300–$800 for a focused foundation assessment if the general inspection flags concerns.
Inspectors also look for:
- Efflorescence (white powder on basement walls)—shows water is moving through the foundation
- Bowing or leaning walls—measured with specialized tools; more than ½ inch deviation over 10 feet is serious
- Gaps between the foundation and frame—suggests settling or shifting
- Water stains or mold—indicates past or active moisture problems
- Cracks in mortar joints between foundation blocks
Most inspectors photograph and measure significant cracks, then estimate whether they're structural or settlement-related. Older homes built before 1950 often have hairline cracks that are normal; newer foundations with significant cracking warrant a structural engineer's opinion before you buy.
The Roof: Age and Condition Matter
Roof repairs run $5,000–$15,000, so inspectors prioritize this system. They assess materials, flashings, ventilation, and remaining life.
Inspectors walk the roof (or view from a ladder/drone if it's steep) to check:
- Shingle condition: curling, missing granules, lifted edges
- Age: asphalt shingles last 15–20 years; metal roofs 40–70 years
- Flashing integrity: gaps or rust around chimneys, vents, and valleys where water breaches happen
- Sagging or waviness: signals structural problems underneath
- Moss or algae growth: in wet climates, common but can accelerate shingle decay
- Ventilation: proper soffit and ridge vents prevent rot and premature aging
A 20-year-old roof in rainy climates is near replacement cost, even if it looks intact from the ground. Budget $8,000–$12,000 for an asphalt roof replacement; metal runs $12,000–$25,000 depending on pitch and material. If the inspection report lists multiple roofing concerns, factor in replacement within 2–5 years.
Load-Bearing Walls and Framing
Structural integrity depends on properly supported framing. Inspectors check whether walls that carry weight are adequately braced and whether modifications have compromised them.
Sagging floor joists indicate rot, water damage, or undersized framing. Inspectors measure deviation with a laser level; more than ¼ inch per 20 feet suggests a problem. Sistered joists (reinforcement boards bolted alongside damaged ones) are a quick fix, costing $2,000–$5,000 per section, but they mask the underlying cause.
Inspectors watch for:
- Cut notches in load-bearing beams from past renovations
- Rusted or corroded metal posts in basements
- Termite damage that reduces wood strength (common in Southeast and warm climates)
- Rot in rim joists where the foundation meets the frame—a water entry point
Any major structural modification (removing walls, adding large openings) without proper engineering is a red flag. It may require expensive retrofitting to meet code.
What Happens After the Report
A thorough structural inspection report runs 20–40 pages. It lists findings by severity: critical, major, minor, and cosmetic. You're not required to fix cosmetic items, but critical issues should be addressed before purchase or priced into your offer.
Use Mercoly to compare local inspectors who specialize in structural assessments—they'll identify problems that general inspectors might miss and can recommend engineers for follow-up work.
Typical next steps: if the report flags concerns, hire a structural engineer ($400–$1,000 for a site visit) to confirm whether repairs are needed and estimate costs. Bring this report back to the seller or renegotiate your offer.
Frequently Asked Questions
Q: How much does a structural inspection cost? A: General home inspections run $300–$500, but specialized structural assessments cost $500–$1,200 depending on home size and complexity.
Q: Can I buy a house with structural cracks if the price is lower? A: Yes, but only if you understand the true cost of repair (often $5,000–$30,000+) and have a structural engineer confirm the fix is straightforward, not a sign of ongoing foundation failure.
Q: What's the difference between a home inspector and a structural engineer? A: Home inspectors identify problems; structural engineers diagnose causes and design repairs, making them essential for serious issues.
Start your search for qualified inspectors in your area—compare credentials, reviews, and expertise on Mercoly today.