in the 1930s, the building's roof was re-built with asphalt and lead flashing to stop leaking. in 1961, flagstone paving was added to the interior floor and the exterior entry patio area. the entire structure was renovated in 2003. despite the changes required over the years, the national park service has been careful to maintain the rustic look of the building. because of its architectural and historic significance, the sinnott memorial building was listed on the national register of historic places in 1988.