Given any d-dimensional Lipschitz Riemannian manifold (M, g) with heat kernel p, we establish uniform upper bounds on p which can always be decoupled in space and time. More precisely, we prove the existence of a constant C > 0 and a bounded Lipschitz function R : M → (0, ∞) such that for every x ∈ M and every t > 0,This allows us to identify suitable weighted Lebesgue spaces w.r.t. the given volume measure as subsets of the Kato class induced by (M, g). In the case ∂M = ∅, we also provide an analogous inclusion for Lebesgue spaces w.r.t. the surface measure on ∂M .We use these insights to give sufficient conditions for a possibly noncomplete Lipschitz Riemannian manifold to be tamed, i.e. to admit a measure-valued lower bound on the Ricci curvature, formulated in a synthetic sense.