cost to widen interior doorway
1 Conservatively, an average of $3,300 to add a safe zero-step entrance to an existing home (a ramp built to code or fill dirt plus raised sidewalk to meet porch, and often the need to raise the porch floor to eliminate the step from porch to interior.). 2  Conservatively, an average of $700 to widen each interior doorway.ore door width is needed than the simple width of a wheelchair, because doors cannot always be approached straight on. . . just as a car needs a lane wider than the car itself to be able to turn a corner. $20 per home is a generous average estimate for wide enough doors (10 doors at $2).