InterNACHI® Certified Professional Inspectors · Clermont, FL
Four Corners Inspection Services — Same team. Same 5-star service.
Free lessons for homeowners & buyers
Plain-English lessons on the systems inside your home, taught by Professor Elias Walls and reviewed by the Four Corners team. Roofs, plumbing, electrical, HVAC, mold and new construction — so you know what you’re looking at before the inspection report arrives.
Foundations · Lesson 2
Lesson 2 of the Foundations series. What goes under and through a Central Florida slab: pad prep and compaction, termite protection (soil or wood), the vapor retarder, plumbing penetrations, curing, and how fast block walls go up.
Foundations · Lesson 1
Lesson 1 of the Foundations series. How a Central Florida slab is built: the sand and karst under it, monolithic vs. stem wall, footers, steel, inspections, and pour day.
Plumbing · Lesson 6
How does a septic system work in Central Florida? The tank, the drainfield, the 24-inch rule, pumping, and where a home inspection stops.
Plumbing · Lesson 5
What is your sewer line made of? Central Florida sewer laterals, roots, sandy soil, uphill pumps, and what a sewer camera inspection shows.
Plumbing · Lesson 4
Why does my drain gurgle? How drains, traps and vents work in Central Florida homes, and why we flag accordion drain pipe under sinks.
Plumbing · Lesson 3
What is the small tank on your water heater? How expansion tanks, relief valves and anode rods work, and what we check on every water heater.
Plumbing · Lesson 2
Pipes in your walls: how to tell galvanized, copper, polybutylene, CPVC and PEX apart, how each fails, and what the printing on the pipe means.
Plumbing · Lesson 1
House water supply explained: the city main, meter and shutoff, why pressure stays up, the 80 psi limit, and what well owners must test.
Roofing · Lesson 6
Lesson 6 of the Roofing series, and the finale. What those black streaks really are, why pressure washing ages a roof ten years in ten minutes, the chemical-only way to clean a roof safely, the maintenance that actually buys you years, and what your roof warranty really covers.
Roofing · Lesson 5
Lesson 5 of the Roofing series. Repair or replace? The event-versus-condition test, Florida service life by covering type, what a replacement actually costs by material, ten reasons the roof is the most important thing on a house you are buying, and how to get every year out of the roof you have.
Roofing · Lesson 4
Lesson 4 of the Roofing series. Roofs leak at the interruptions — pipe boots, wall flashing, valleys, skylights and chimneys — almost never in the middle. Why the ceiling stain is never where the hole is, and which Florida ceiling stains are not roof leaks at all.
Roofing · Lesson 3
Lesson 3 of the Roofing series. Florida rewrote its wind mitigation form on April 1, 2026 — nine questions instead of seven, proof required for every feature. What each question means, how Hurricane Andrew created these standards, and why one broken truss is a far bigger deal than homeowners think.
Roofing · Lesson 2
How to read a roof: how shingle, tile, metal and flat roofs age in Florida sun, and why tile and spray-foamed attics can hide leaks.
Roofing · Lesson 1
How roof age is counted in Florida, why it decides insurance, what the law protects after 15 years, and why no coating makes a roof younger.
Electrical · Lesson 6
The finale of the Electrical series. The electrical findings that stop a sale or hold up a Florida insurance policy are rarely the age of the wire — they're what somebody added afterward. Inside the panel: double taps, doubled neutrals, neutrals and grounds sharing a bar, wrong-size conductors, missing clamps, burnt lugs, and the missing cover screws nobody thinks twice about.
Electrical · Lesson 5
GFCI vs AFCI: what each one protects you from, why a breaker cannot see shock or arcs, and the test button almost nobody presses.
Electrical · Lesson 4
Lesson 4 of the Electrical series. How home wiring went from no protection at all, to the sacrificial fuse, to the resettable breaker — and how the post-war race to power the American home produced both the modern panel and a handful of brand names that still make an inspector go quiet. Plus what a breaker was never able to see, and the two devices invented to see it.
Electrical · Lesson 3
What is the third hole in an outlet for? Why the slots differ, what ground does, and why a two-slot outlet or a cheater plug is a problem.
Electrical · Lesson 2
Lesson 2 of the Electrical series. Knob and tube was 1910's best wiring — hand-placed ceramic, soldered splices, open-air cooling. Professor Walls explains what it is, why the original work was genuinely good, what a century of heat, insulation, and amateur additions did to it, and why insurance carriers flinch when the 4-point finds it energized.
Electrical · Lesson 1
How old homes got electricity, from knob-and-tube to the post-war ranch, and what that wiring history means if you are buying an older house.
Mold · Lesson 4
The mold series finale. In nearly every Florida home, mold hides in the same four places — the bathroom, the kitchen cabinets, the garage air handler, and the attic. Professor Walls tours all four, teaches you to read them with an inspector's eyes, and explains how sampling and lab testing turn 'I think something's off' into verified answers on inspection day.
Mold · Lesson 3
One number decides whether mold can grow: your indoor humidity. Keep it under 60% and mold can't get the water it needs. Professor Walls covers the target number, the $20 tool that reveals it, why your AC (and your older home) may struggle in Florida heat, and the modern gadgets that guard the spots you can't see.
Mold · Lesson 2
Mold needs moisture — the one thing you can control. But most of the water that feeds it is invisible: humidity in the air, condensation on cold surfaces, a slow hidden drip, and the steam from a long shower with no fan. Professor Walls teaches you to find the water you can't see.
Mold · Lesson 1
How does mold form in a house? The four things it needs, the common household types, and why moisture is the one you can control.
HVAC
The series finale. The cheapest, most-ignored job in your house — changing your air filter — is also the one that saves your air conditioner from a frozen coil and a sky-high power bill. Professor Walls closes the HVAC series with the maintenance that actually matters, and a graduation.
HVAC
R-22, R-410A, R-454B — the gas inside your air conditioner has a history, and it's quietly writing your repair bills. Professor Walls tells the story of three generations of refrigerant and shows you how to read your system's clock right off the data plate.
HVAC
Why is your AC unit where it is? Professor Walls explains how placement affects comfort, air quality, and safety — gas-unit carbon monoxide rules, the sweating-and-mold problem, and the truth about sealed spray-foam attics.
HVAC
AC parts explained: what the condenser, air handler and evaporator coil do, what they look like, and how long they last in Florida.
HVAC
How does an air conditioner work? A plain-English look at how your system moves heat out of a Florida home instead of making cold.
New Construction
Your builder reminds you to submit your warranty list at eleven months — but knowing what belongs on it is the hard part. Professor Walls shows you how to answer that email like a scholar, before the clock runs out.
New Construction
Your inspector already covered the roof and the systems. Blue tape day is about something only you can judge — does this house match the one you fell in love with at the model home?
New Construction
Professor Walls gives the room-by-room tour of a Central Florida pre-drywall inspection — hurricane straps, wet framing, termite pretreatment, and the finds that vanish behind drywall forever.
Meet the Professor
The teaching face of the Four Corners Knowledge Center — and the real, certified inspectors behind every lesson he presents.
New Construction
The delays, budget creep, warranty fine print, and missed inspection windows behind the new-build horror stories — and how Southern Lake County buyers stay out of them.
New Construction
Professor Walls teaches the three independent inspections — pre-drywall, final, and 11-month warranty — that protect your investment in a new Central Florida home.
