The San Francisco Planning Department is cracking down on landlords who lease industrial spaces to office tenants and has opened investigations into more than 100 cases of tech and professional service firms allegedly filling up buildings zoned for manufacturing, automotive repair, warehousing or the arts.

After responding to just two such complaints in 2013 and four in 2014, the Planning Department’s zoning enforcement team opened 108 cases in 2015. Two months into this year, the department has already launched 21 investigations.

The increase in complaints highlights the growing sentiment that San Francisco, particularly the eastern portion of the Mission District, is losing the manufacturers, suppliers, artisans and automotive shops that defined its character and provided jobs to blue-collar residents. And those residents are disappearing too, driven out by a rush of condo conversions and the economic pressures that inevitably accompany the transition of a neighborhood from funky to trendy.

A 2014 study found there are about 60,000 PDR — it stands for production, design and repair — jobs in San Francisco. Forty years ago there were 165,000 such jobs.

“It’s not the offices themselves we have a problem with; it’s the displacement we’re seeing,” said Peter Papadopoulos of the Mission Cultural Action Network. “It creates an increasing displacement pressure on blue-collar jobs, communities of color and artists who are leaving the city in large numbers.”

Office space at a premium

Office tenants are willing to pay well over twice what PDR commands — creative tech space goes for $70 a square foot in SoMa or the Inner Mission.

With so much money to be made, it’s not surprising that brokers and landlords are willing to look the other way when it comes to zoning violations, especially when investment groups are buying PDR buildings at prices that only make sense if leased to tech companies. Recently, the city hosted a forum with 80 commercial real estate brokers to advise them on “compliance in PDR zones.”

“Brokers and tenants need to be aware of PDR zoning,” said Corey Teague, assistant zoning administrator for the city. “They need to do their due diligence and be more careful about signing leases.”

Eastern neighborhoods

The Mission, Potrero Hill and Dogpatch were all part of a 2010 rezoning of the eastern neighborhoods, which sought to protect PDR uses while encouraging some infill housing development near BART and Muni lines. The rezoning set up a planning process in which property owners could petition to “legitimize” a portion of office uses already existing in PDR buildings. It also zoned large swaths of land as “urban mixed use,” which allows PDR space to be replaced with housing.

The result is that new housing is springing up on land once occupied by PDR uses. The city is working on an inventory of how much PDR space has been lost since the eastern neighborhoods plan went into effect, something that Papadopoulos says is long overdue.

“We have been frustrated with lack of data on PDR loss,” he said. “We feel like the city is flying blind.”

Meanwhile the proliferation of cubicles and computer terminals in former warehouses — not to mention the growth of high-end housing in those neighborhoods — is putting the squeeze on the city’s resurgent boutique manufacturing sector, the apparel makers and breweries that have been thriving in recent years.

At the time of the eastern neighborhoods debate in 2010, property owners argued that the city’s industrial sector had been waning for decades and that excluding office space and housing from those neighborhoods would do little but ensure the survival of empty buildings. Instead, however, the city has seen a sharp increase in the number of boutique manufacturers.

Manufacturing on upswing

SFMade, a trade group that promotes manufacturing in San Francisco, has grown from 100 to 665 members in the past five years, and its members now occupy well over 1 million square feet. SFMade Executive Director Kate Sofis says the city needs to add at least 200,000 square feet of PDR space a year to keep up with demand.

While Sofis said that the crackdown on illegal uses of PDR space has yet to benefit the city’s new generation of makers, there have been some success stories. A building at 298 Alabama St. in the Mission that Google declined to buy because of its zoning was instead acquired by Dandelion Chocolate, which will use it for production and was able to gain a variance to include retail. Heath Ceramics took over 2900 18th St., a former laundry the owner had hoped to knock down for housing.

Tim Marcus of Milkman Sound, which makes custom amplifiers in a closet-sized space on Toland Drive in the Bayview, said he has had no luck finding a larger industrial space. Every time he finds an appropriate space “it is insanely overpriced.”

“They are looking for what I call the fake money,” he said. “I am in a position where I could really grow my business and have employees and do a lot of shipping, but I am kind of up against the ceiling because of the space.”

Discomfort and confusion

For tenants caught up in the zoning wars, life can be uncomfortable, or confusing.

In May, the messaging app company Layer invited customers to tour its new headquarters at 470 Alabama St. for “drinks, snacks and swag.”

But what the company didn’t realize was that the Planning Department had received a complaint that the PDR-zoned building was being built out as tech offices. A few months later Layer was gone from Alabama Street, forced to lease a new space on Townsend. The property owner found a new tenant, Web-based custom clothing maker Trumaker.

Trumaker CEO Mark Lovas said the space worked out well for them — to a point. The company used the Alabama Street space for its clothing storage, distribution center, design and prototyping, and some production. In the end, however, Trumaker wanted a retail showroom, which would have required a variance — PDR allows wholesale sales, but not walk-in retail.

Trumaker still has some storage and shipping at 470 Alabama St., but it is moving its showroom and retail near Union Square.

“I think protecting PDR is good, but it would be better if the definition of PDR were to be expanded slightly to allow for multiuse sites,” Lovas said.

Sofis said it remains to be seen whether the push to rid PDR spaces of office tenants will benefit manufacturers. Of the 129 complaints about PDR violations filed in the past 14 months, 26 have been settled. About 10 of those were found to have no violation. The rest have been “abated” — generally by the property owners finding a new tenant who complies with the zoning.

Sharon Steuer, a Mission District artist who has watched her fellow artists priced out of the neighborhood and their spaces replaced with tech offices, said the city needs to give enforcement planners more power to investigate what’s going on in these buildings. The law gives property owners 15 days before an inspection is required — enough time, she said, to remove telltale desks or computers. The fine for a violation is $250 a day — not a lot of money when tech companies will pay $70 or $80 a square foot for office space.

She said the enforcement planners should be empowered to do random checks.

“If there is a complaint of a violation, why are inspectors not allowed in there immediately?” she said.

‘A fishing expedition’

But attorney Brett Gladstone, who represents property owners, said a lot of complaints are being lodged without evidence.

“If it’s essentially a fishing expedition, then that is not a good use of city resources,” Gladstone said.

Furthermore, defining what is and is not PDR can be complicated, Gladstone said. It’s not uncommon for businesses to mix product prototyping with computer-based design. And sometimes tenants are not up front with property owners about how they will be using the space, he said.

“You are not automatically disqualified as PDR just because you have a couple of computers, although if you go into a space and it’s all cubicles and computers, it makes it more difficult to make the case that it’s PDR,” said Teague, the zoning administrator.

J.K. Dineen is a San Francisco Chronicle staff writer. Email: jkdineen@sfchronicle.com Twitter: @sfjkdineen