Tearing out existing tile is expensive, dusty and slow. The good news: cork-rubber flooring can usually be installed directly over sound, level ceramic or porcelain tile, provided the substrate prep is done properly. Skip the prep and grout lines telegraph through within a year.
When you can install over tile
- Tiles are firmly bonded to the substrate (no hollow sounds when tapped).
- No more than around 5% of tiles are cracked, lifted or missing.
- Floor is structurally level to within manufacturer tolerance (typically 3 mm over 3 m).
- Slab moisture is within spec, the manufacturer specifies relative humidity not exceeding 75% (ASTM F2170).
- Total floor build-up will still clear doors and transitions.
When you cannot
Tiles that are drumming, lifting or covering an unknown substrate are a no. Same for floors with active moisture issues, severe lippage, or polished finishes that will not accept an adhesive. In those cases the existing tile has to come up first.
The substrate prep that makes or breaks the job
Comcork is thinner than people expect, supplied in 2.5, 3.2 and 4.5 mm. Anything happening underneath will telegraph through. The non-negotiable steps:
- Mechanical clean of the tile surface, grind off any sealer or polish.
- Self-levelling compound poured across the full floor to fill grout lines and even out lippage.
- Moisture test of the slab below; epoxy DPM applied if readings exceed threshold.
- Final levelness check before adhesive goes down.
Cutting these corners is what causes the grout-line telegraphing visible on cheap installs. Cork-rubber laid over a properly prepped tile substrate looks identical to one laid on a fresh slab. Follow the manufacturer's installation specification. Comcork calls for Mapei Ultrabond Eco VS90 Plus acrylic adhesive in dry interior areas and Mapei Adesilex G19 two-part epoxy-polyurethane in wet interior or exterior areas, spread with a 1.6 mm V-notched trowel per the Comcork Installation Instructions.
Cost vs tearing out
Self-levelling and prep typically adds 15 to 25% to the installed cost. Tearing out tile, disposing of the waste, and re-screeding usually adds 60 to 100% and roughly a week to the program. For most renovations, installing over sound tile wins on both budget and timeline.