Why Renown could absorb major reconstruction

Why were Renown and Repulse structurally closer to battleships when Hood carried the thicker belt?

Their battleship-derived framing and denser subdivision supported heavier reconstruction even though their original belt armor was thinner.

The Renown class began as a Revenge-class battleship design, a structural origin more important here than belt thickness alone. Denser framing and subdivision gave the hulls more internal support than a conventional battlecruiser possessed. Renown endured two large reconstructions, and constructors regarded her as a safer place to learn before attempting comparable work on Hood. Reconstruction capacity depends on the structure behind the armor, not simply the plate visible in specifications.