VANCOUVER -- Hussain Khateer is beefing up security at his construction sites.

“Theft on jobs sites has always been an issue,” said Khatheer, owner of Vancouver General Contractors. “But with the increased costs of lumber now, it’s starting to become more of an easier target than, say, power tools and equipment.”

On Wednesday, Vancouver police issued a warning about an increase in thefts on the city's west side, with thousands of dollars reported stolen from local constructions sites.

The most recent theft was reported last week in Kerrisdale, where three pallets of roofing shingles and 60 sheets of plywood were taken after being left insecure.

“There have been at least seven construction sites on the west side of Vancouver that have been targeted,” said Sgt. Steve Addison. “There were two incidents in January, one in March, three in April and the most recent one was on May 10.”

Thefts have also been reported in the Arbutus Ridge, Kitsilano, Marpole and Dunbar neighbourhoods, and in one case the culprits got away with more than $10,000 in plywood.

“The majority of these incidents have occurred over weekends between the end of work on Friday and people returning to work on Monday,” said Addison. "This likely coincides with the increasing lumber prices that we have been seeing.”

The price of lumber has gone up a whopping 400 percent.

“It’s gone up dramatically,” said Gary Bull, forestry economics professor at UBC, adding there’s a lot of different reasons at play.

He explained there have been disruptions in the forest inventory due to the wildfires and pine beetles in 2017 and 2018.

“This greatly accelerated the production of lumber in those years as industry was trying to use the logs before they became unusable,” Bull told CTV News. "These forests have been used up so now there’s a constraint on what we call the timber supply to the existing saw mills.”

Challenges with climate change are also affecting the future forest and how that will be managed, he added.

“The demand is more around the spike in housing starts and the remodelling, renovation industry and how that took off in 2020,” said Bull, and “our emphasis on replacing steel and cement with mass timber.”

Khatheer said they are paying somewhere between two and three times more on lumber as they did in the past. The increase in costs is making the entire industry more challenging, especially when you add in the thefts.

“It’s a tough pill to swallow as a homeowner when your contractor comes back and says unfortunately we have to buy more materials and more products because they were stolen on the job sites,” said Khatheer. "The unfortunate thing is the cost of construction just keeps going up and up and up as a result of some of these increased costs for lumber and materials.”

Bull said the prices are starting to come back down, however.

“Lumber futures are declining by around 10 percent, so we will see the market correct," he said.

In the meantime, Khatheer's company has made changes to how they do things to ensure supplies are more secure. Deliveries only arrive as needed, they’ve added security cameras to some sites, and in cases where there’s a lot of equipment, they hire private security.

But once the lumber is taken, Khatheer said it’s nearly impossible to get back. It’s not an item that can be tracked or traced easily.

“Once it’s gone, it’s gone, it can be on a thousand different job sites form now on,” he said. "A lot of times there’s really no point on reporting it to police. There’s not really much that they can do.”

The Vancouver Police Department is hoping people will report the thefts anyway, and has set up a tip line at 604-717-4034. Tipsters who want to remain anonymous can instead call Crime Stoppers at 1-800-222-8477.

With files from CTV News Vancouver's Alyse Kotyk