GUIDED by Chinese craftsmen, a team of French and Chinese volunteers uses old-fashioned skills, tools and authentic materials to restore old houses along Suzhou's 800-year-old Pingjiang Road. Tan Weiyun puts on her work gloves.

One of Suzhou's main attractions is 1,600-meter-long Pingjiang Road, paved with flagstones, lined with willow trees and old brick houses alongside a canal. Lanes extend from the ancient road into old neighborhoods where life moves slowly.

In the past two weeks the northern part of the road, which is usually quiet, was bustling with volunteers wearing yellow safety helmets and wielding old-time construction tools. They shuttled back and forth between the dilapidated houses, carrying timber, laying bricks, mixing mortar, building walls, chipping stones and doing assorted other construction work.

The volunteers, seven French citizens and seven Chinese, were taking part in the Pingjiang Road restoration project, launched by France-based Union Rempart, which promotes conservation of world heritage, and the Ruan Yisan Heritage Foundation, named after a famous activist preservationist. Ruan, who leads the project, is a native of Suzhou, in Shanghai's neighboring Jiangsu Province, known for being stubborn and persistent about meticulous preservation.

Rempart sends volunteers around France and to other countries on work projects where they provide manual labor and learn about culture, and architecture and conservation methods around the world. Work ranges from taking part in archeological digs to rebuilding castles.

This is the second work camp Rempart has set up in China. The first was in Pingyao old town, northern China's Shanxi Province.

From September 3 through last Friday, when the project ended, the volunteers took part in authentic rebuilding (not faking it with new "old" buildings) of four buildings on the 800-year-old road.

They worked as plasterers, bricklayers, carpenters, stone masons, tile roofers and other construction workers, learning first-hand how ancient Chinese buildings were put up. They used traditional tools only, no electric saws or machinery were allowed, no metal nails, no concrete - they made their own cement and mortar. They used old bricks and if they cannot find them, they made their own bricks the traditional way.

They got safety goggles and helmets. Safety precautions were strict.

These volunteers didn't need construction skills, knowledge of architecture or particular experience - they learnt on the job.

"What is required is their strong motivation to participate in the preservation work and their passion for heritage restoration," said team leader Marie Georges Pagel-Brousse, the vice president of Union Rempart (rampart or fortification). "To learn, share and exchange are what we care about most," she told Shanghai Daily.

The volunteers ranged in age from 17 to 63 and included students, professionals, housewives, civil servants, teachers and others.

Still, they were carefully selected.

Retired nurse and anesthetist Catherine Luzel, age 63, was working as a carpenter, planing a raw piece plank from a tree. "I paint and carve at home and I like to work with wood and plants," she said. She was a perfect candidate.

Persistent architect

Project leader Ruan is a 77-year-old architect, urban planner and stout defender of China's ancient architectural heritage. He was born on a lane off Pingjiang Road, but the house is long gone. He pointed out the spot.

This is not the first time he has butted heads with urban planners bent on doing away with historic buildings to make way for shiny, new, profitable ones - or to tear down dilapidated originals and build new replicas.

The local government at first rejected Ruan's plans for meticulous Pingjiang Road reconstruction as being too time-consuming and costly. Officials said "no" many times.

"But I insisted and insisted," Ruan told Shanghai Daily. "To build another building, to me, is faking it, not restoration. If there is no way to restore something, we just let it be and try to present its original shape with the help of modern materials. That's honesty."

The Pingjiang Road restoration project, was actually started more than 20 years ago. These volunteers were working on one part of it. They were taught on-site by experts and journeymen craftsmen from Suzhou Taihu Lake Ancient Architecture Building and Restoration.

They learnt how to fit wood together without metal nails, using pegs or mortis and tenon construction; how to cut stone and build with it, then render, or plaster over it; how to work with roof tiles and how to finish interiors.

"It's a precious opportunity for them to learn and exchange the different ancient restoration techniques of China and Europe," Ruan said. "We hope this project will draw attention to heritage preservation."

More than 90 percent of the heritage building conservation projects in China are run by the government.

The Pingjiang Road project is one of the first times the public has actively taken part in heritage conservation.

Authentic rebuilding

Ruan insists on four basic principles in any restoration: Authenticity, integrity, sustainability and what he calls "readability," meaning that people can look at the structure and clearly see or "read' information about the house and history.

"That requires original construction materials and ancient skills; the structures, patterns and even the environment must be maintained," Ruan said.

Workers can only use traditional implements that were used hundreds of years ago, and their hands. They use bricks and stone from the collapsed walls of old houses. If there are not enough bricks, then the workers make them.

"It's quite time-consuming, but it's the only way to maintain authenticity," said Wang Jiagen, a technician of the Suzhou Taihu Lake restoration group.

The old-fashioned bricks, known as "one-kilogram" bricks, are made from the soil and clay from nearby mountains. It's mixed with water and turned to mud; then workers trample on it for hours to make it elastic and sticky - in the past oxen were driven over and over the clay. It's then placed in wooden molds, covered with a bamboo sheet and dried in the shade for two days, not in the sun that could make it crack. Then it's fired in an earthen kiln for a week.

"It's tiring and complicated, but I am totally astonished by the ancient people's wisdom. I admire them so much," said volunteer Yu Jing from Suzhou, who works in an architectural firm.

Volunteer project

In the Rempart project, volunteers pay their own way, take along work gloves, sleeping bags and rough clothes. Safety equipment is provided. Everybody pitches in with chores. Volunteers share local cooking recipes from home and take along musical instruments.

Frenchman Pierre Frusard, 22, is a history major. He has taken part in several projects in France, but this is his first venture outside the country. One of his jobs was to carry partly restored heavy wooden posts from one house to another for further restoration.

"Ancient Chinese architecture and restoration skills are entirely different from European skills. I've learned a lot, which I will digest for a long time," he said.

Since they cannot use concrete (broken stones or gravel, cement, sand and water), which was not used hundreds of years ago, the volunteers instead made their own mortar for brickwork in the walls. It was made of local yellow soil and quicklime. They must use their gloved hands to blend the two.

"This seems as firm as modern concrete," said 17-year-old Hu Yesheng, who was stirring the sticky liquid with both hands. The high school student from Suzhou saw a recruitment notice online, sent an application and was selected.

Leave it alone

For structures that are too far gone for renovation, the guiding principle is leave it alone and retain what's there.

At the northern tip of Pingjiang Road, there's a gateway built by merchant Wang Jingchun in 1842. What visitors see today is actually a combination of the old and the new - but the distinction is clear.

In most places, the plaster facing is gone, leaving the old bricks and mortar exposed. A new wooden frame was constructed for support and the surface was covered with a protective glass-like surface - through it, visitors can read a plaque describing the gate and the preservation work. Where the gate crumbled and could not be rebuilt, a new structure connects with the old one.

"People can see clearly what is truly old and what is new," Ruan said, "what's left and what's lost."