HDMI.org guarantees the cables to work as intended only up to 10m. As it's an install with little recourse to changing cables, I want to be absolutely certain that the cable will work.
From HDMI.org website:
How do I run HDMI cables longer than 10 meters?
There are many HDMI Adopters working on HDMI solutions that extend a cable’s effective distance from the typical 10 meter range to much longer lengths. These companies manufacture a variety of solutions that include active cables (active electronics built into cables that boost and extend the cable’s signal), repeaters, amplifiers as well as CAT5/6 and fiber solutions.