This document provides a cost estimation for retrofitting a 10-unit housing building. It lists various interventions like scaffolding, facade cleaning, foundation drainage, new fixtures, roof renovation, rainwater recovery system, acoustic isolation, a new wooden porch, and indoor repainting. The total cost for the retrofitting project is estimated to be around $376,000 or around $37,600 per unit. The interventions are aimed at improving issues like mold, drainage, ventilation, and noise insulation while reusing rainwater and potentially engaging inhabitants in some work.