Another 5% of sites were issued with improvement notices and a number of others are being considered for prosecution.
Falls from height are the biggest cause of death on building sites, with 37 deaths and 1424 injuries to workers recorded in 2001/02. Twelve workers have fallen to their deaths since 1 April this year.
The site closure figures are an improvement on those from last year's blitz, which shut down 460 sites out of 1113 visited.
Kevin Myers, chief inspector for construction at the HSE, said that the 28% of inadequate sites were deemed "so poor they required enforcement action", despite an apparent rise in awareness.
He said: "There are still people working in construction who do not fully understand their duties to manage falls from height risks."
The blitz was part of Don't Fall for It, a Europe-wide campaign to reduce falls from height. The HSE plans to conduct another wave of inspections in September.