It is established a series of criteria for continuous and homeomorphic extension to the boundary of the so-called lower Q-homeomorphisms f between domains in R n = R n ∪ {∞}, n 2, under integral constraints of the type Φ(Q n−1 (x)) dm(x) < ∞ with a convex non-decreasing functionIt is shown that integral conditions on the function Φ found by us are not only sufficient but also necessary for a continuous extension of f to the boundary. It is given also applications of the obtained results to the mappings with finite area distortion and, in particular, to finitely bi-Lipschitz mappings that are a far reaching generalization of isometries as well as quasiisometries in R n . In particular, it is obtained a generalization and strengthening of the well-known theorem by Gehring-Martio on a homeomorphic extension to boundaries of quasiconformal mappings between QED (quasiextremal distance) domains.2000 Mathematics Subject Classification: Primary 30C65; Secondary 30C75 Key words: mappings with finite area distortion, moduli of families of surfaces, finitely biLipschitz mappings, weakly flat and strongly accessible boundaries.