Home rental vacancies in the Denver area grew slightly in the third quarter, with the vacancy rate for condos, duplexes and houses reaching 3.4% during the period, the Colorado Department of Housing said. The rate is up from 2.9% in the second quarter and 2.6% a year earlier. Triplexes and fourplexes experienced the highest vacancy rate of 4% for three months ended Sept. 30. Meanwhile, the vacancy rate on detached houses hit 2.6%. Vacancies on rental townhomes and condominiums hit 3.3% and 3.8%, respectively. "The small increase in vacancies reflects the fact that we’re continuing to see new inventory come onto the market," said Susan Melton, owner of Assured Management in the Lakewood, Colo., area. "We're still being approached by homeowners who can't sell their homes, but don't want to manage rentals themselves, and we also have established investor clients who are adding to the inventory of rental homes they already own," Melton said. "The net effect has been a slowly expanding inventory, which can produce some new vacancies while also preventing rent levels from taking off the way they have in some apartment properties." The average rent for the Denver metropolitan area rose to $1,049 in the third quarter, up from $1,041 a year earlier. Single-family rentals on average have been staying on the market for 24.5 days, down from 36 days last year. Write to Kerri Panchuk.