In the immediate aftermath of the April fire that destroyed much of Notre Dame cathedral, French billionaires were quick to make huge pledges to help fund rebuilding.

But even though their fortunes have grown substantially in the past six months, little of that money has yet been donated.

The ultra-wealthy French donors don't seem eager to help fund the dirtiest kind of cleanup work, which must be done before any rebuilding.

Instead, they're more likely be vying to fund the construction of new architectural features for posterity.

They were quick to pledge but are slow to give. The billionaire families that promised to donate hundreds of millions of dollars each to reconstruct Notre Dame cathedral after the storied structure caught fire in April have yet to fully uphold those commitments, according to a cathedral spokesperson. That's the case, even though some French tycoons' fortunes having grown dramatically during the first part of the year.

The 14 people from France who earned spots on Bloomberg's Billionaires Index -- a number of whom raced to support reconstruction efforts in April -- have collectively become $78 billion more wealthy since Dec. 31. Yet while French business moguls pledged more than $500 million to the Notre Dame rebuilding cause, little of that money has landed in the state's coffers.

Bernaud Arnault and LVMH

LVMH CEO Bernaud Arnault, No. 3 on the Bloomberg list with a net worth of $101 billion, has seen his fortune grow by $32.4 billion since the end of last year. The Arnault family and LVMH Group, which owns Louis Vuitton, Fendi and other luxury brands, pledged 200 million euros ($224 million) to support reconstruction efforts. But to date, they've only given 10 million euros ($11.2 million) to the cause, according to the Fondation Notre Dame, one of the four official charities the government selected to feed its fundraiser.

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The 10 million euro down payment will be used to secure the construction site, Christophe Rousselot, general delegate for the Fondation Notre Dame, told CBS MoneyWatch. The effort includes erecting a second scaffold to take down the first, built before the fire, to repair the spire. "It solidified in the stone with the fire," Rousselot said.

All this is required just to lay the foundation so that subsequent efforts to rebuild the cathedral can commence.

"Before we repair the vault, we have to be sure of its solidity," he said. "Their money will contribute to that." Once these efforts are complete, the foundation will request additional funds from Arnault and other families, Rousselot said.

Francoise Bettencourt Meyers and L'Oreal

L'Oreal heiress Francoise Bettencourt Meyers, worth an estimated $56.2 billion, added $10.1 billion to her wealth during the same time period. The Bettencourt Meyers family and L'Oreal group announced a 100 million euro ($112 million) donation the day after the fire erupted, while the Bettencourt Schueller Foundation matched the pledge.

"The Bettencourt Meyers family and the Bettencourt Schueller foundation, touched by this drama that unites beyond cultures and beliefs, intend to take part in the collective effort and talents needed to meet this immense challenge, which touches the heart of our country," L'Oreal said in a statement in April.

As of June 14, the Bettencourt Schueller foundation had yet to hand over any money because it wants to ensure its donation aligns with its ethos, the Associated Press reported.

Kering Chairman Francois Pinault

Francois Pinault, chairman of luxury-goods group Kering, is worth $38.2 billion, having become $8.2 billion richer over the course of the same six months. The Pinault family also promised 100 million euros to be directed to reconstruction efforts. But those funds have yet to materialize in full.

Kering spokesman Jean-Jacques Aillagon said the family pledged to donate through the Fondation Notre Dame, one of the four organizations selected by the state to raise funds for the cathedral's restoration. The funds will be disbursed in stages, as work progresses and the government requests them, he told CBS MoneyWatch.

"It was agreed, between us and the foundation, that it would solicit funds gradually as requested by the State, owner of the monument and responsible for the work. A first ask of 10 million [euros] was addressed to us on June 19. The following day, June 20th, this sum was sent to the Fondation Notre Dame's account," Aillagon told CBS MoneyWatch.

"As soon as the needs of the construction site are such that the Fondation Notre Dame will approach the Pinault family for another request, it will be executed, according to the prior contractual agreements," he said.

Aillagon added that he and Pinault accompanied General Jean-Louis Georgelin, who's overseeing rebuilding efforts, to the site on June 2 to assess the scope of the work.

Rousselot of the Fondation Notre Dame expects it to take about four months just to secure the construction site.

Total Chairman Patrick Pouyanné

French energy company Total, whose Chairman Patick Pouyanne isn't on the Bloomberg Billionaires list, also pledged to donate 100 million euros to repair the cathedral through the Fondation du Patrimoine, one of the government's four official charity partners. The foundation is in the process of signing agreements with the state as well as corporate sponsors, a spokesperson told CBS MoneyWatch.

Over the coming weeks, the foundation will make its first 24.6 million euro payment ($27.7 million) consisting of individuals' donations. "Then, gradually, as the work on Notre Dame advances, the state will request more funds from the foundation, which will then turn to its corporate sponsors," Fondation du Patrimoine spokesman Laurence Levy said. Similar agreements have been struck between French families that pledged large donations and other charitable organizations, Levy said.

Waiting before paying



As of June 14, the so-called big donors hadn't donated a cent, Andre Finot, senior press official at Notre Dame, told the Associated Press at the time. "They want to know what exactly their money is being spent on and if they agree to it before they hand it over, and not just to pay employees' salaries," he said at the time.

That changed last week when the Fondation Notre Dame announced that the Arnault and Pinault families had each contributed 10 million euros to the cause. Still, that represents just a fraction of what they each pledged.

Health risks



The cleanup required before reconstruction can begin is underway and has so far been funded mostly by French and American individuals' donations to charitable foundations. Three-hundred tons of lead are estimated to have melted from the cathedral's roof and released into the atmosphere during the fire. High levels of lead now permeate the soil on Ile de la Cite and its environs, which poses a health risk for Parisians.

American charity Friends of Notre Dame de Paris and Paris-based Fondation Notre Dame have so far contributed 3.6 million euros to the restoration effort. Friends of Notre Dame de Paris, established in 2017 to support ongoing structural maintenance to the cathedral, said 95% of the 1.8 million euros it received in donations came from American individuals and corporations.

"We are a U.S. charity created before the fire to fund the restoration of the cathedral, and naturally it is being used now as a vehicle to fund the rebuilding of the cathedral after the fire at the international level," foundation President Michel Picaud told CBS MoneyWatch. Similarly, the Fondation Notre Dame's 1.8 million euro contribution came from funds collected before the fire erupted.

"The first donation was used for the safety work with the objective of putting the cathedral in relatively good shape before the rebuilding process can began. Those funds were pretty evenly split between what came from the international foundation and the French one," Picaud said.

What's the vision?



Wealthy French don't seem to be eager to help fund the cleanup work, Celia Verot, director general of the Fondation du Patrimoine, told the Associated Press. Instead, donors have particular visions and are waiting to see how they align with the government's plans to repair the cathedral. "It's a voluntary donation, so the companies are waiting for the government's vision to see what precisely they want to fund," she explained.

Another foundation official, who spoke on the condition of anonymity, said the cleanup tasks currently underway aren't an appealing cause for wealthy donors. Rather, they'll more likely be vying to fund the construction of new architectural features for posterity.

Olivier de Challus, a chief guide and architectural expert at Notre Dame, said the direction of the reconstruction work has yet to be defined while the fire's damage is still being assessed. "It doesn't matter that the big donors haven't yet paid because the choices about the spire and the major architectural decisions will happen probably late in 2020," Challus told the Associated Press. "That's when the large sums of money will be required."

Rousselot concurred: "That's when we'll have a better sense of the total work that is required. The analyses are still ongoing and are very complex. When a building is partially heated between 800 and 1,000 degrees, the nature of the building can change. So we have to be patient." he said.