250 Water St. Image courtesy of Tsoi Kobus Design

East Cambridge maintained its position as the region’s top destination for lab tenants, with asking rents topping $101 per square foot, triple-net, in the fourth quarter.

With vacancies lingering below 1 percent, rents are expected to rise even further, according to CBRE’s fourth quarter Office and Lab MarketView report.

“Throughout 2019, we saw many trends amount in Cambridge including office to lab conversions, co-working lab spaces, defensive leasing and new construction in areas proximate to East Cambridge,” Connor Channell, senior research analyst for CBRE New England, said in a statement.

Office rents rose 10 percent to $77.61 per square foot citywide, including a record $92.54 in East Cambridge.

The office and lab availability rate rose to 7.3 percent partly because of new construction including the speculative 250 Water St. building at Cambridge Crossing, which will contain 480,000 square feet of office and lab space.

In West Cambridge, where life science companies have leased large blocks at properties such as the Alewife Research Center, availabilities decreased to 10.5 percent. The Mid- and West Cambridge markets also benefited from the strength of Kendall Square, with asking lab rents averaging $80 per square foot triple-net, CBRE said.

This report has been updated to correct the square-footage of 250 Water St. at Cambridge Crossing.