Voids and gaps
Voids or gaps will occur if the insulation is installed at too low a density or the cavity is not completely filled. Voids are most likely to occur at the top of wall cavities, above windows, around doorways, and in the corners of ceiling cavities. Voids also occur if the installation holes are improperly located between the vertical framing studs or if there are too few fill holes. It also may be difficult to achieve the recommended R-values with loose-fill insulation in the eave area of an attic.