<p>For smoke filling in enclosures having floor leaks, both the expansion leakage term and the entrainment plume term need to be included, which make the smoke filling equation an inseparable nonlinear differential equation. Several closed-form approximate solutions of the smoke filling can be found in the literature for flat roofs. However, the smoke filling under sloping roofs is quite different, and none of existing closed-form solutions is applicable to the sloping-roof scenarios. In this work, the smoke filling in enclosure growing fires with floor leaks and sloping roofs is derived. The smoke filling process is divided into two stages. The first is the smoke filling in the upper part of the room, i.e., the triangular prism enclosed by the roof panels and the gables. The second is the smoke filling in the lower part of the room when the smoke layer expands beyond the triangular prism. For the first stage, a novel closed-form solution is derived through asymptotic analyses based on introduction of a virtual scenario. In the virtual scenario, the smoke filling is exactly the same as that in the real scenario only when the smoke interface is higher than the gable base or the corresponding level. This closed-form solution agrees well with the numerical solution. For the second stage, the concept of "equivalent flat roof" is introduced to make the existing solutions applicable and a method is proposed to estimate the equivalent flat-roof height. Since the proposed models are based on the Zukoski plume correlation, a coefficient is introduced into the entrainment plume term to reflect the correlation's uncertainty. An illustrative example is presented to demonstrate how to derive the descent smoke layer time as a function of the smoke layer interface height. It is shown that the proposed solutions work well for both the stages.</p>