Contents:
- Why the Hidden Subfloor Matters More Than the Flooring You Choose
- Slab homes versus framed floors
- What Is Under Your Carpet: The Most Common Discoveries in Tampa Bay Homes
- A bare concrete slab with paint marks and pencil lines
- Cracks: hairline shrinkage versus displacement
- Old adhesive, glue residue and black mastic
- Old vinyl sheet or VCT tiles
- Plywood or OSB subfloor on raised homes and second floors
- Hidden hardwood in older homes
- Pet urine stains and lingering odor
- Moisture and mold signs
- Uneven spots, humps and low areas
- Tack strip nail holes and damaged perimeter
- What Each Discovery Means for LVP, Laminate, Tile and Engineered Hardwood
- Luxury vinyl plank (LVP) and luxury vinyl tile
- Laminate
- Porcelain and ceramic tile
- Engineered hardwood
- How Professional Floor Prep Turns a Rough Subfloor into a Ready Surface
- Step 1: Clean out and remove the old flooring
- Step 2: Repair the cracks
- Step 3: Grind the weak top layer
- Step 4: Prime
- Step 5: Level where needed
- Step 6: Quality control at every stage
- A Seasonal Timeline for Carpet Removal and Hard Flooring in Tampa Bay
- January through March: the sweet spot
- April and May: still favorable, getting busier
- June through September: rainy season and hurricane season
- October through December: the second window
- Practical Tips Before the Carpet Comes Up
- Mistakes others make that you can avoid
- Real Examples: Illustrative Scenarios from Under the Carpet
- The ranch house with the secret map
- The upstairs bedroom with a history
- The bungalow with the hidden treasure and the furry tenant
- The slab that sloped
- Why Local Experience Shapes the Outcome
- Frequently Asked Questions
- Can I install LVP directly on concrete after removing carpet?
- How do I know if the black glue under my carpet contains asbestos?
- Will pet urine odor come back after new flooring goes in?
- How long does floor prep take before installation can start?
- Are hairline cracks in my slab a reason not to install tile?
- Your Next Step Starts with a Corner of Carpet
What is under your carpet right now, and could it change the hard flooring you have already picked out? Most homeowners never think about it until the first strip of old pile peels back and the room reveals a floor nobody has seen in fifteen, twenty, maybe forty years. Sometimes it is a clean gray slab. Sometimes it is paint drips, cracks, black tarry film, warped plywood, or a dark ring where a beloved dog spent its golden years.
Each of those surprises has a meaning. Some are cosmetic and disappear under a coat of primer. Others decide whether a luxury vinyl plank will click together smoothly, whether porcelain tile will crack in a year, or whether engineered hardwood will cup during the first humid August. This guide walks through everything you are likely to uncover, what each discovery means for the floor you want, and how proper preparation turns a rough surface into a reliable base.
Why the Hidden Subfloor Matters More Than the Flooring You Choose
Carpet is the most forgiving floor covering ever made. A thick pad hides dips, ridges, hairline cracks, old glue and small stains. It cushions a squeaky board. It even disguises a slab that slopes a half inch from wall to wall.
Hard flooring offers no such mercy. A rigid plank or a 24-inch porcelain tile transmits every flaw beneath it. A high spot becomes a pivot point that makes click-lock joints flex and eventually separate. A low spot creates a hollow that sounds like a drum under your heels. Moisture trapped under an impermeable surface has nowhere to go, so it collects, feeds mold and loosens adhesive.
Across Tampa Bay, the most common answer to the question of what lies beneath is concrete. Many single-story homes in Pinellas, Hillsborough and Pasco counties sit on slab-on-grade foundations, poured directly on compacted fill. Raised homes, stilt homes near the coast, condos with wood framing and second floors of two-story houses tell a different story: plywood or oriented strand board (OSB) over joists. Knowing which type you have narrows down the list of likely discoveries before the first carpet knife comes out.
Slab homes versus framed floors
On a slab, the main concerns are cracks, flatness, old adhesives, moisture vapor rising from the ground, and any residue left by earlier floor coverings. On a wood subfloor, the concerns shift toward structural stiffness, fastener condition, water damage, rot, squeaks and the thickness of the panels. Both types can hide pet damage and both can hide mold.
What Is Under Your Carpet: The Most Common Discoveries in Tampa Bay Homes
Here is the field guide, roughly from most to least common.
1. A bare concrete slab with paint marks and pencil lines
This is the most common and least worrying discovery. Builders and painters rarely protect a slab that is going to be carpeted, so you may see overspray along the baseboards, roller drips in the middle of the room, drywall mud splatter, pencil or marker notes from the original framing crew, and the faint outline of where interior walls were laid out.
What it means: Paint and drywall mud sit on top of the concrete and weaken the bond for any glued material. For floating LVP or laminate, light paint drips are mostly harmless once scraped flat. For tile set in thin-set mortar or for glue-down planks, the residue must be ground or scraped off so the adhesive can grip clean, porous concrete.
2. Cracks: hairline shrinkage versus displacement
Almost every concrete slab cracks. Concrete shrinks as it cures, and that shrinkage produces thin, random lines, often running diagonally from corners or straight across a room. These hairline shrinkage cracks are typically narrower than a credit card is thick, and both sides of the crack sit at the same height.
Displacement cracks are a different animal. Run your palm across the crack. If one side is higher than the other, if the crack is wider than about 1/8 inch, or if it has visibly grown since the carpet went down, the slab has moved. Causes range from settling soil and poor compaction to, rarely, sinkhole activity.
What it means: Hairline cracks are routine. They get cleaned out and filled before flooring goes down, and tile installers often add a crack isolation membrane so the crack cannot telegraph through the grout. Displacement cracks need a closer look. If one side has shifted, a structural engineer or foundation specialist should evaluate the slab before any rigid flooring is installed, because tile and stone will simply crack along the same line.
3. Old adhesive, glue residue and black mastic
Not every carpet in its first life was a carpet. Many slabs carried vinyl sheet goods, tile, or glue-down carpet before the current wall-to-wall was installed. The evidence is a layer of glue: yellow or tan carpet adhesive, gray latex residue, or a hard, shiny black coating known as cutback adhesive or black mastic.
Black mastic deserves a pause. In older homes, especially those built or remodeled more than four decades ago, black cutback adhesives sometimes contained asbestos. Intact and undisturbed, it poses little risk. The danger begins when someone sands, grinds or scrapes it dry, which can release fibers into the air.
What it means: Before any grinding, sanding or aggressive scraping, a sample should be sent to an accredited lab. If the test is negative, the residue can be ground off or, in some cases, encapsulated with a compatible primer or leveling product. If it is positive, a licensed abatement contractor handles removal according to Florida and federal rules, or the floor is encapsulated under a new layer without disturbing the mastic. Floating floors can sometimes be installed over properly encapsulated residue; glue-down products and tile usually need a clean, sound surface.
4. Old vinyl sheet or VCT tiles
Peel back carpet in an older house and you might find squares of vinyl composition tile, often the classic 9-by-9-inch size, or a layer of sheet vinyl that someone decided to carpet over instead of removing. The 9-inch format in particular is a known red flag, because many tiles of that era were manufactured with asbestos fibers.
What it means: Treat old resilient tile the same way as black mastic. Do not break, sand or pry it up dry until it has been tested. If it is asbestos-free and firmly bonded, some floating floors can go right over it after leveling. If it is loose, curling or cracked, it has to come up, and the adhesive beneath it becomes the next question.
Expert insight: “The floor under a carpet is a record of every decision made in that room,” says Simone Achebe, a certified home inspector and indoor air quality specialist. “What I tell homeowners is simple: anything black, shiny, or in nine-inch squares gets tested before it gets touched. A lab test costs far less than cleaning up an airborne fiber problem, and in my experience most results come back clean, which means you can move forward with confidence instead of guesswork.”
5. Plywood or OSB subfloor on raised homes and second floors
Upstairs bedrooms, raised coastal homes and some older framed houses reveal wood panels instead of concrete. Both are perfectly good subfloors when dry, stiff and securely fastened.
The trouble signs are easy to spot once you know them:
- Squeaks: loose nails rubbing against joists as the panel flexes.
- Dark stains around toilets, tubs, sliders and exterior doors: evidence of past leaks.
- Swollen edges on OSB: panels that absorbed water and expanded, leaving ridges at the seams.
- Soft or spongy areas: delamination or rot that weakens the panel.
- Visible bounce: joists or panels too thin for rigid flooring, especially tile.
What it means: Squeaks get fixed by screwing the panels down into the joists. Swollen seams get sanded flat. Rotten or soft sections must be cut out and replaced with new panels of matching thickness. Tile on a wood subfloor needs extra stiffness, often with an added layer of plywood or a cement backer board or uncoupling membrane, because ceramic and stone cannot tolerate flex.
6. Hidden hardwood in older homes
Few discoveries are as thrilling. In some older bungalows around St. Petersburg, Tampa and the historic neighborhoods of the region, wall-to-wall carpet was laid right over original oak or heart pine strip flooring. Dull or scarred boards are often still solid enough to refinish.
What it means: Before committing to a new floor, check the boards for thickness (look at a floor register or threshold edge), water damage, termite trails and how many times they have already been sanded. If they are sound, refinishing may be an option. For a new look anyway, solid hardwood can serve as a subfloor for floating floors, though it needs to be flat and fastened tightly. Tile directly over strip hardwood is generally a bad idea without significant reinforcement.
7. Pet urine stains and lingering odor
Carpet pad acts like a sponge. Years of accidents soak through pad and into concrete or wood, leaving yellow, brown or dark rings and an ammonia smell that reappears every time the humidity climbs.
What it means: Simply covering the stain with new flooring rarely ends the smell. The usual sequence is a thorough enzyme treatment that breaks down the uric acid crystals, complete drying, and then a sealing primer that locks remaining odor molecules below the surface. Badly saturated plywood is often cheaper to replace than to treat. For glue-down products, the primer also needs to be compatible with the adhesive, so product selection matters.
8. Moisture and mold signs
Look for a white, chalky powder on the concrete (efflorescence, mineral salts carried up by moisture), dark staining at the pad underside, a musty smell, rust on tack strip nails, or discolored, fuzzy growth along baseboards. Florida slabs often sit close to the water table and many older ones were poured without a vapor barrier underneath.
What it means: Moisture is the silent enemy of hard flooring. It breaks down adhesives, swells laminate cores, cups engineered hardwood and creates the conditions for mold under impermeable surfaces. A slab with visible moisture signs needs proper testing, typically an in-situ relative humidity probe or a calcium chloride test, to compare readings against the flooring manufacturer’s limits. If the numbers run high, a moisture barrier or vapor-retarding primer becomes part of the plan. Active mold should be addressed and the source of water found before any new floor goes in.
9. Uneven spots, humps and low areas
Lay a long straightedge or a six-foot level across the floor and slide it around. You will likely find places where light shines underneath, and other spots where the straightedge rocks on a hump. Common culprits are trowel ridges, settled plumbing trenches and seams in wood panels.
What it means: Most manufacturers of LVP and laminate specify a flatness tolerance around 3/16 inch over 10 feet. Large-format tile is stricter, often around 1/8 inch over 10 feet. Exceeding the tolerance can void a warranty and lead to failed joints, lippage between tiles and hollow sounds. Humps get ground down, low areas get filled with patch or self-leveling compound.
10. Tack strip nail holes and damaged perimeter
Along every wall you will find the narrow tack strips that held the carpet in place, plus a row of small holes and chips where they were nailed into concrete or wood. Removing those strips is its own project, covered in detail elsewhere, so here the point is what they leave behind: chipped concrete edges, protruding nail stubs and occasional spalling near the walls.
What it means: Every nail stub must come out or be ground flush, and the holes and chips get filled. Leftover nails can puncture underlayment, telegraph through thin vinyl, or keep a tile from bedding fully along the edge of the room.
What Each Discovery Means for LVP, Laminate, Tile and Engineered Hardwood
The same condition can be minor for one flooring type and a deal-breaker for another.
Luxury vinyl plank (LVP) and luxury vinyl tile
Rigid-core LVP is the most popular carpet replacement in the region, mostly because it is waterproof and handles Florida humidity well. It is forgiving of minor cosmetic issues like paint drips and tiny cracks, especially as a floating floor. Its weak points are flatness and protruding debris. A thin plank over a hump will flex at the joints; a nail stub or hardened glue blob can show as a bump through thinner products. Glue-down LVP needs a clean, flat, primed surface, so adhesive residue and pet stains matter more.
- Most sensitive to: unevenness, debris, sharp ridges.
- Moderately sensitive to: moisture (the plank tolerates it, but mold underneath does not care how waterproof the top layer is).
- Least sensitive to: cosmetic stains and shrinkage cracks.
Laminate
Laminate has a fiberboard core that swells when wet, even in water-resistant versions. On a Florida slab, a proper moisture barrier underlayment is non-negotiable. It shares LVP’s sensitivity to flatness and adds a strong sensitivity to moisture. Pet odor that remains in the slab can also migrate into the core over time.
- Most sensitive to: moisture, unevenness.
- Moderately sensitive to: lingering odor, squeaky wood subfloors.
- Least sensitive to: paint marks and minor hairline cracks.
Porcelain and ceramic tile
Tile is the classic floor in Tampa Bay homes for good reason: it shrugs off humidity, pets and sandy feet. Yet it is the least tolerant of movement. Any crack that moves will crack the tile above it. Any flex in a wood subfloor will crack grout and loosen tiles. Thin-set needs a clean, porous surface to bond, so paint, mastic and old glue must go. Flatness requirements are strict, especially for large-format and plank-style porcelain.
- Most sensitive to: displacement cracks, deflection, contaminants that block bonding, flatness.
- Moderately sensitive to: hairline cracks (managed with crack isolation membranes).
- Least sensitive to: moisture in the slab, within reason.
Engineered hardwood
Engineered hardwood combines a real wood surface with a stable plywood or composite core, which makes it far better suited to slabs than solid hardwood. It still reacts to moisture by cupping and gapping, so moisture testing and a vapor barrier are essential. Glue-down installations require flat, clean, primed concrete. Floating installations need a flat surface and a quality underlayment.
- Most sensitive to: moisture, flatness.
- Moderately sensitive to: adhesive residue (for glue-down), squeaks on wood subfloors.
What the Pros Know: Experienced installers never judge a subfloor by eye alone. They check it three ways before ordering material: a long straightedge or laser level for flatness, a moisture test for vapor, and a simple tap test (a coin or the handle of a screwdriver) across tile-bound slabs and patched areas to hear hollow, delaminated spots. They also compare every reading against the specific product’s installation guide, because a plank that tolerates 3/16 inch over 10 feet and a tile that demands 1/8 inch need two different prep plans for the very same room.
How Professional Floor Prep Turns a Rough Subfloor into a Ready Surface
Once the carpet is gone, preparation begins. Tampa Bay Floors, a licensed and insured tile and flooring contractor based in St. Petersburg, describes a clear, staged process for this work, and it reflects how serious prep is done.

Step 1: Clean out and remove the old flooring
Everything comes up first: carpet, pad, tack strips, loose vinyl and any old flooring that cannot stay. The crew of Tampa Bay Floors cuts carpet and pad into strips and rolls them up before carrying them out, which keeps dust from spreading through the house. Leftover nails, which typically sit about 1/4 to 3/8 inch deep in the subfloor, are pried out. Then the entire surface is vacuumed so every crack and stain is visible.
Step 2: Repair the cracks
Shrinkage cracks are cleaned out and filled with an appropriate repair material so they cannot telegraph through the new floor. Damaged perimeter edges from tack strips, chipped areas and nail holes get patched at the same stage.
Step 3: Grind the weak top layer
Concrete often has a dusty, weak surface layer, known as laitance, plus paint, drywall mud and glue residue. Grinding removes that layer and exposes sound concrete, which dramatically improves adhesion for thin-set, adhesives and leveling compounds. Any residue suspected of containing asbestos must be tested before this step, never after.
Step 4: Prime
One or two coats of primer seal the surface, control porosity and help the next layer bond. Primer is also where pet odor control and some moisture management happen, using products chosen for the specific situation. Curing time depends on the materials selected for the project.
Step 5: Level where needed
Leveling starts with measurement. A laser level maps how much the height varies across the room. From there, the method follows the numbers:
- Self-leveling compound for variations up to about 20 mm, which covers most residential slabs.
- Cement-based compound when moisture resistance matters, such as ground-floor slabs in humid climates. It takes longer to cure.
- Gypsum-based compound where moisture resistance is not a concern.
- Cement-concrete screed for large variations of around 80 mm or more.
The leveling sequence includes prep and crack repair, primer, reference markers set at the highest point, pouring according to the manufacturer’s instructions, and spreading the material to release air bubbles. Only after that does the glue-down flooring go down. Floating floors typically need less prep, while glue-down products demand a truly flat surface.
Step 6: Quality control at every stage
Each step gets checked before the next begins. Problems compound: a missed hump becomes a weak bond, then a hollow tile. Homeowners who want this level of rigor can book floor preparation services in Tampa as a standalone job or as part of a full installation package. Cost depends on the size of the area, the amount of prep required and the flooring type, which is why a free on-site estimate makes more sense than a guess over the phone.
A Seasonal Timeline for Carpet Removal and Hard Flooring in Tampa Bay
Humidity, rain, hurricanes and holidays all affect how smoothly a project goes.
January through March: the sweet spot
The driest, mildest months of the year are ideal for moisture testing and curing. Slabs tend to give their most stable readings, cement-based compounds cure on schedule, and homes are often closed up with air conditioning running at moderate levels. Plan carpet removal early in this window to have new floors before spring visitors arrive.
April and May: still favorable, getting busier
Weather remains mostly dry, but demand climbs as homeowners prepare to sell or host summer guests. Booking a free estimate with Tampa Bay Floors in March helps secure a spot.
June through September: rainy season and hurricane season
Daily afternoon storms raise indoor humidity and can push slab moisture readings higher. Projects still happen, but acclimating materials matters more, air conditioning must run continuously, and curing times may stretch. Hurricane season, which officially runs through November, also adds the risk of flooding. After any water intrusion, carpet becomes a mold risk within a day or two and should be pulled quickly.
October through December: the second window
Humidity drops as fall arrives, making this the second-best stretch for prep and installation. Expect a rush of homeowners wanting new floors before Thanksgiving and holiday gatherings, so schedule by early October. For anyone reading this in October 2026, a project started now can comfortably finish before the holidays, as long as testing reveals no major surprises.
A realistic timeline for a typical slab home runs like this: one day for carpet removal and cleanup, one to two days for testing, crack repair, grinding and priming, one day for leveling if needed, then a curing window that depends on the products used. Installation follows. Add time if asbestos testing, abatement, structural review or mold remediation enters the picture.
Practical Tips Before the Carpet Comes Up
- Peek first. Lift a corner of carpet inside a closet. Pull back the pad. You will learn if the base is concrete or wood, whether there is old tile or mastic, and whether the pad is stained. Five minutes of looking can reshape your budget expectations.
- Find the age of the house and any earlier remodels. Property records and past permits help you guess whether old adhesives or resilient tile could contain asbestos.
- Order the asbestos test early. Spot black residue or 9-inch tiles during your peek? Then send a sample before scheduling demolition. Waiting on lab results after the room is already torn up wastes days.
- Choose your flooring type tentatively, then confirm after prep assessment. A slab that needs extensive leveling might push you toward a floating LVP instead of large-format porcelain, or vice versa if moisture is the bigger issue.
- Budget a contingency. Many experienced remodelers set aside 10 to 20 percent of the flooring budget for subfloor surprises. If nothing comes up, the money goes back in your pocket.
- Plan for the pets. Pets returning to a freshly treated room sometimes re-mark old spots. Keep them out until the enzyme treatment, primer and new floor are all in place.
- Photograph everything. Pictures of the exposed subfloor are useful for warranty documentation, insurance claims after storms, and future remodels.
Mistakes others make that you can avoid
Some contractors and DIYers skip steps that seem minor in the moment. A common example is a crew that installs click-lock planks straight over a slab with visible humps, assuming the underlayment will absorb them. Within months the joints along the high spots begin to gap and creak. Another is a weekend renovator who sands black mastic with a rented floor sander to save money, unknowingly sending potentially hazardous dust through the HVAC system. A third is the installer who lays tile over a framed second floor without checking deflection, only to see cracked grout lines appear in a straight row along a joist. None of these failures came from bad flooring.
That is why choosing who pulls the carpet matters as much as choosing who installs the new floor. A thoughtful carpet removal company in St. Petersburg treats demolition as the first inspection, not just a haul-away job.
Real Examples: Illustrative Scenarios from Under the Carpet
The following scenarios are composites created to illustrate common situations. They are not accounts of specific clients.
The ranch house with the secret map
Picture a Pinellas County ranch home. The owners want warm-toned LVP throughout. When the carpet comes up, the living room reveals a clean slab, scattered paint drips and three long hairline cracks running from the corners of a sliding door. In the dining room, there is a rectangle of black adhesive where a previous owner once had sheet vinyl.
The path forward: the adhesive gets sampled first. While waiting on the lab, the crew scrapes and grinds the paint drips in the living room, cleans out and fills the hairline cracks, and maps flatness with a laser level. The lab result comes back negative, so the adhesive is ground off. Two shallow low areas near the kitchen get self-leveling compound. Primer goes down, and the LVP installs over a flat, clean surface.
The upstairs bedroom with a history
Now imagine a two-story home where an upstairs bedroom sits next to a bathroom. The owners want engineered hardwood. Under the carpet, the OSB subfloor near the shared wall is darker than the rest, with swollen seams and a spot that feels soft underfoot. There are also two squeaks near the doorway.
The path forward: before touching the bedroom, a plumber checks the bathroom for an active leak and finds an old, slow seep at the toilet supply line. Once repaired, the soft OSB section is cut out and replaced with new panels of matching thickness. Swollen seams get sanded flat, and the whole floor is screwed down to the joists to silence the squeaks. Only then does the engineered hardwood go down.
The bungalow with the hidden treasure and the furry tenant
Consider an older bungalow in a historic St. Petersburg neighborhood. Under the carpet lies original oak strip flooring, mostly sound, but with several dark urine stains in one bedroom and a few water-stained boards near an exterior door.
The path forward splits. The owners love the oak in the living areas, so those rooms are sanded and refinished. In the stained bedroom, the worst boards are replaced, the remaining stains are treated with enzyme cleaner and sealed with an odor-blocking primer, and porcelain tile is ruled out because the strip floor would need too much reinforcement. A floating engineered floor goes in instead.
The slab that sloped
Finally, picture a ground-floor condo where the owners dream of 24-by-48-inch porcelain tile. The laser level shows almost 30 mm of variation from the entry to the back wall, likely from settling near an old plumbing trench. Self-leveling compound alone will not cover it in one pour.
The path forward: the deepest section is built up first, then a cement-based self-leveler, chosen for moisture resistance at grade level, is poured across the room with reference markers set from the high point. After curing, a crack isolation membrane goes over a long shrinkage crack, and the large tiles finally have the flat foundation they demand.
Why Local Experience Shapes the Outcome
Tampa Bay homes face slabs at grade, high humidity, summer storms and coastal flooding. Tampa Bay Floors has written about that last point in detail, noting that after the Helene flooding near St. Pete Beach, correctly installed tile held up best, while tile with hollow spots trapped water and risked hidden mold. That observation ties directly back to what you find under the carpet: a floor is only as resilient as the preparation beneath it.
The company handles projects of nearly any size, from a single bedroom to commercial spaces such as hotels, restaurants and spas, and it covers the full sequence in-house: carpet and tile demolition, floor prep, leveling, waterproofing and installation of tile, LVP, laminate and engineered hardwood. For homeowners, that continuity means the people who discover the black mastic or the soft plywood are the same people responsible for the final floor, so nothing gets lost between trades. Working with Tampa Bay Floors also means one free estimate covers the whole picture rather than separate quotes from a demolition crew, a prep specialist and an installer.
Frequently Asked Questions
Can I install LVP directly on concrete after removing carpet?
Often, yes, but only after cleaning, removing nails and residue, filling cracks and confirming the slab meets the manufacturer’s flatness and moisture limits. Floating LVP is more forgiving than glue-down, yet neither tolerates humps, nail stubs or trapped moisture.
How do I know if the black glue under my carpet contains asbestos?
You cannot tell by looking. Have a small sample tested by an accredited lab before any sanding, grinding or scraping. If results are positive, use a licensed abatement contractor or encapsulate the residue without disturbing it.
Will pet urine odor come back after new flooring goes in?
It can if the stains are simply covered. Enzyme treatment, full drying and a sealing primer on concrete, or replacement of badly soaked plywood, give the best chance of eliminating odor permanently.
How long does floor prep take before installation can start?
For a typical room, cleaning, crack repair, grinding and priming can take one to two days, with leveling adding another day plus curing time. As Tampa Bay Floors points out, curing depends on the materials chosen for each project, and moisture remediation or asbestos abatement can extend the schedule.
Are hairline cracks in my slab a reason not to install tile?
No. Hairline shrinkage cracks are normal and are managed by filling them and using a crack isolation membrane under the tile. Cracks with height differences or that keep widening should be evaluated by a structural professional first.

Your Next Step Starts with a Corner of Carpet
Pick a closet tonight, lift the corner, and look. Note concrete or wood, glue or tile, stains or dampness, and take a photo. That single image gives any estimator a head start and shows if testing should happen before demolition. Bring that photo to a free estimate with Tampa Bay Floors, ask how they plan to handle each condition you spotted, and expect a specific answer for every one. The floor you walk on for the next twenty years will be decided in those first few hours after the carpet comes up.