Which approach best ensures a flat substrate for tile on a PEB floor?

• A. Checking With A Level Only
• B. Using Decorative Tiles To Conceal Unevenness
• C. Using Self-Leveling Underlayment Or Patching Compounds, And Verifying With A Straightedge And Long Level
• D. Cutting Tiles To Fit Unevenness

Answer: (C)

Achieving a truly flat substrate is essential for a durable tile install. The best approach is to use self-leveling underlayment or patching compounds to fill low spots, smooth out irregularities, and bring the entire floor to a consistent plane. After applying, you verify the surface with a straightedge and a long level across multiple directions to confirm there are no high ridges or low patches beyond the acceptable tolerance. This method directly corrects the surface, promoting a strong bond between the substrate and tile and reducing the risk of lippage, cracking, or debonding—especially important on a PEB floor where unevenness can come from deck joints or settlement.

Using decorative tiles to conceal unevenness won’t fix the underlying problem and can lead to tiles that don’t sit flush. Cutting tiles to fit unevenness shifts the problem to the tile edges and often creates weak edges and poor grout lines. Relying only on a level check doesn’t correct the surface either.