Globally, hazards are increasingly threatening housing each year, and housing constructed outside the formal sector may be particularly vulnerable. Yet, limited studies have investigated the perceptions of those responsible for designing and building this housing. These safety perceptions motivate the informal housing construction practices that ultimately determine housing safety. Thus, this study investigates the multi-hazard housing safety perceptions of individuals involved with housing construction in Puerto Rico. We surveyed 345 builders and hardware store employees across Puerto Rico to understand their perceptions of expected housing damage in hurricanes and earthquakes, important mitigation measures, and barriers to safer housing construction. Our results reveal that prior hazard experience did not influence perceptions of expected housing damage, but previous housing construction experience did. Respondents viewed wood and concrete housing as less safe in hurricanes and earthquakes, respectively. Yet, respondents appeared uncertain about the importance of mitigation measures for concrete houses in earthquakes, likely due to a combination of limited earthquake experience and “hidden” reinforcement detailing in a reinforced concrete house. Interestingly, our results also show that respondents perceive technical construction capacity as a major barrier to safer informal housing construction rather than resource constraints alone. These findings suggest areas for technical construction capacity development for Puerto Rico’s informal construction sector.