I've been handling tile installation and restoration orders for a Florida-based supply company for about eight years now. I personally made—and documented—three pretty significant mistakes in my first three years. All together, they cost roughly $6,400 in wasted budget and rework. Now I maintain our team's pre-project checklist, and I can tell you: there is no single "right" tile or method. Your situation determines your solution.
This article breaks down the three most common project scenarios I see in Florida—new construction, full renovation, and quick facelift—and gives you specific advice for each based on what I messed up.
Why There's No Universal Answer
Before I get into the specifics, you need to understand the three factors that drive every decision on a tile job:
- Project type: New build vs. renovation (they require vastly different prep work).
- Condition of the substrate: Are you tiling over concrete, wood subfloor, or old tile?
- Your risk tolerance: Can you handle a 1-week delay for proper waterproofing, or do you need it done by Friday?
Once you know where you fall on those three axes, you can pick your path. Here's what I learned the hard way.
Scenario 1: The New Build (Concrete Slab)
This is the most straightforward scenario, but also where I made my first big mistake.
“In my first year (2018), I ordered 2,000 sq ft of 24x48 porcelain tile for a new commercial build. The slab was fresh, looked flat, and I assumed we were good. I didn't check moisture levels or slab flatness with a straightedge. Three months after installation, we had tenting and lippage on 40 tiles. The GC made us rip out and redo 600 sq ft. Cost to me: $2,100 in material and labor. The lesson: never skip a moisture test and a 10-foot straightedge check on a new slab.”
What I recommend now:
- Always: Test the slab for moisture vapor emission (ASTM F1869 or F2170). In Florida, this is non-negotiable given our humidity.
- Always: Check flatness with a 10-foot straightedge. The industry standard (TCNA) says you want no more than 1/4 inch gap in any direction. If you have voids, fill them before tiling.
- Tile choice: Porcelain or concrete-look porcelain is ideal for new slabs. Avoid large-format clay barrel tiles unless you have a structurally very flat slab—they are more prone to lippage.
- Thinset: Use a medium-bed mortar for large-format tiles. Don't cheat with standard thin-set.
Bottom line: If you have a new slab and you do your prep work, this is a pretty manageable project. Skip the prep, and you're gonna have a bad time.
Scenario 2: The Full Renovation (Removing Old Tile)
This scenario is way more common in South Florida—tearing out old tile, maybe dealing with a concrete slab that has old adhesive residue, or removing tile over a wood subfloor.
My second mistake happened here.
“In September 2021, I managed a bathroom renovation where we removed the old ceramic tile from a wood subfloor. The demolition pulled up some of the backer board. I thought, 'No big deal, just put down new cement board and tile over it.' I didn't check for level across the whole floor area. We ended up with a 1/2 inch drop at the doorway. My crew was done, the homeowner noticed. We had to pull up three rows, sister the joists, and redo the underlayment. $900 in extra labor and materials, plus a 2-week delay.”
What I recommend now:
- Always: After demolition, check the subfloor for level and structural integrity. Use a self-leveling compound if needed (Ardex or equivalent).
- Tile choice: For renovations, I'd lean towards thinner porcelain tiles (8mm or 9mm) or even wood-look planks. They are easier to cut, easier to level, and less likely to cause lippage over an uneven subfloor.
- Waterproofing: For bathrooms, you need a proper waterproofing membrane (like Schluter Kerdi or Wedi board). Don't rely solely on the tile. Check the Florida Building Code requirements for wet areas.
- Grout: Use a flexible grout (like epoxy or urethane) over wood subfloor to accommodate expansion and contraction.
Pro tip: If your budget is tight on a renovation, spend the money on leveling and waterproofing, not on expensive tile. A $3/sq ft porcelain tile installed perfectly looks way better than a $10/sq ft tile installed poorly.
Scenario 3: The Quick Facelift (Tiling Over Existing Tile)
This is the gray area. Sometimes you can tile over existing tile, and sometimes you can't. The answer isn't a simple yes or no.
Here's my rule of thumb after my third mistake.
“In late 2022, I had a client who wanted to refresh their kitchen backsplash. The existing subway tile was well-bonded to the wall. I said, 'Sure, we can skim coat and tile over it.' Looked fine for about four months. Then we got a call: tiles were popping off. The issue? The glaze on the old tile was glossy. The skim coat didn't bond properly, and thermal expansion from the kitchen did the rest. I had to pay a crew to remove the new tile, grind down the old glaze, and re-tile. $1,200 wasted. I could have avoided it by grinding the old surface or using a bonding agent.”
What I recommend now:
- Can you tile over old tile? The answer depends on three things: (1) Is the old tile fully bonded with no hollow spots? (2) Is the surface matte or smooth glazed? (3) Is the total thickness increase okay for transitions?
- If yes: You must scarify (grind) the glossy surface, clean it thoroughly, and use a bonding primer (like Mapei Eco Prim Grip) before applying the new thinset.
- If no: Remove the old tile. It's more work but less risk of failure.
- Best tile for this: Small-format tiles (like 3x6 subway or 2x8 wood look) work better than large-format tiles over old tile because they accommodate minor surface irregularities.
Quick side note: If you're looking for a durable surface for your tile project (like a pizza stone for a fireplace hearth or a natural stone threshold), make sure you consider the thermal expansion coefficient—ceramics and stone behave differently than engineered products like Zagg screen protectors (though those are for electronics, not construction).
How to Figure Out Which Scenario You're In
Here's a simple three-question checklist. Answer honestly, and you'll know your path.
- Is your subfloor a concrete slab at least 30 days old, or a wood subfloor with no previous tile? If yes, you're Scenario 1. Go straight to prep work.
- Are you removing existing tile and expecting to deal with an uneven surface? If yes, you're Scenario 2. Focus on leveling and waterproofing.
- Are you trying to save time and money by tiling over existing tile? If yes, you're Scenario 3. Test the old tile, scarify the surface, use a bonding agent—or remove it.
I'm not saying there aren't other scenarios (like tiling over radiant floor heating or exterior installations), but these three cover about 80% of the residential and light commercial projects I've seen in Florida.
So glad I started using that checklist a few years ago. I almost went with "just gut feel" on another project in 2023, which would have meant ignoring a moisture reading of 8 lbs per 1,000 sq ft (industry max for tile is 5 lbs). Dodged a bullet when I took the time to test.
Bottom line: The right tile and the right prep depend entirely on your project type, substrate condition, and timeline. Don't accept a one-size-fits-all answer. Use the decision tree above, and if you're still unsure, hire a contractor who does proper moisture and flatness testing. It's cheaper than redoing the job.
