The Park City construction industry in September enjoyed its best month of the year, boosted by another series of permits for alterations and additions, the Building Department said.

According to the department, permits valued at a little more than $8.5 million combined were issued in September. In the same month the year before, a little less than $2.9 million worth of permits was issued.

September was the second consecutive solid month. The department in August issued permits worth a little less than $6.4 million combined.

The year-to-date figure in 2012 is significantly outpacing the number in 2011. Through the end of September, the department had tallied approximately $42.2 million worth of permits. Through the same period in 2011, the number sat at $29.8 million.

Two seven-figure permits were issued in September. One, valued at a little more than $2.7 million, was for an addition at 692 Main St. The other was pegged at $1.8 million for an addition at 12 Oak Court.

Alterations and additions have had an outsized impact on the construction numbers in years since the recession as property owners decided to fix up or add to existing structures instead of building new ones. Permits for alterations and additions, though, typically are not as valuable as those for new structures.

Alterations and additions in September accounted for 79.1 percent of the overall valuation for the month.

The department issued one permit for a single family home and one permit for a duplex.

The number of electrical, plumbing and mechanical permits climbed from the previous month and the previous September.

The Building Department reported a daily inspection average of 72 in September, about the same as the previous month but down sharply from the 141 each day in the previous September.

The numbers through the end of September are likely encouraging to the construction industry as it appears there could be a strong end to the building year given the figures in September and in August.

But the tally continues to trail significantly the numbers posted in the years between the 2002 Winter Olympics and the onset of the recession. The industry posted a series of record-setting years in that period.

The recession struck at a time when the numbers were expected to level off anyway as the number of significant development sites inside Park City dwindled.