With National Grid's lockout of gas workers now in its third month, some communities are halting all non-emergency gas service installations, and some local home designers and construction workers say the lockout is having a ripple effect on the construction industry.

Architect Jay Walter of Entasis Architects PC has been designing restorations, additions and remodels of older homes in Newton for 25 years.

Walter says he has two projects that have been impacted by gas re-connection delays.

"It's fall now, and the contractor just got a letter from National Grid saying that they don't anticipate re-connecting the gas until January 2019," he said.

Without National Grid employees to do the work, Walter says one work-around is temporary installments of propane until gas lines are reconnected, but that is costly and adds delays.

"If the construction goes on as scheduled and is completed and the lockout is not over, all [of] the equipment in the house has to be converted to propane so that the homeowners can use it," he said.

Walter says these homes would also eventually need to be converted back to natural gas, which can be expensive.

Meanwhile, some communities — including Quincy, Boston and Lowell — have halted non-emergency gas work in solidarity with the locked-out workers.

National Grid locked out nearly 1,200 workers union gas workers on June 25, when their existing contract expired and negotiations reached an impasse. The company says it has been using managers and independent contractors in the meantime.

National Grid did not immediately respond to WGBH News' request for comment.