Ethan’s house is symbolic of lost prosperity and vitality.
Ethan and his house are both run-down and barely held together. Although Ethan is only in his fifties, he looks much older. His house is similarly decrepit. It is “unusually forlorn and stunted,” which describes Ethan perfectly. Ethan “lived in a depth of moral isolation too remote for casual access” and keeps people out.
Just as Ethan is crippled, the house is crippled. Ethan had to take down the “L” part of the house, which makes the house look especially “stunted.” The house is described like a human, because Ethan is the house personified.
The black wraith of a deciduous creeper flapped from the porch, and the thin wooden walls, under their worn coat of paint, seemed to shiver in the wind that had risen with the ceasing of the snow. (Prologue)
The condition of the house helps drive home Ethan’s condition. The house is a symbol of a better time, when both it and Ethan had hope. Now, they are both disintegrating into nothing.