  In paper 0704.4003, Bondarko recently defined the notion of weight structure,
and proved that the category $\DgM$ of geometrical motives over a perfect field
k, as defined and studied by Voevodsky, Suslin and Friedlander, is canonically
equipped with such a structure. Building on this result, and under a condition
on the weights avoided by the boundary motive, we describe a method to
construct intrinsically in $\DgM$ a motivic version of interior cohomology of
smooth, but possibly non-projective schemes. In a sequel to this work, this
method will be applied to Shimura varieties.
