  Multi-particle states with additional pions are expected to result in a
difficult-to-control excited-state contamination in lattice simulations. We
show that heavy meson chiral perturbation theory can be employed to estimate
the contamination due to two-particle $B\pi$ states in various $B$-meson
observables like the $B$-meson decay constant and the $BB^*\pi$ coupling. We
work in the static limit and to next-to-leading order in the chiral expansion,
i.e. including $\rm O(p)$. The $B\pi$ states are found to typically
overestimate the observables at the few percent level. We determine two of the
LECs from $B\to \pi$ form factor computations of the KEK group and discuss ways
to determine the others. In particular two LECs which are associated with
smeared interpolating fields seem to be easily accessible and thus open up a
way to systematically study the effect of smearing on excited state effects.
