Tesla’s CEO Elon Musk is used to having his decisions scrutinized under a microscope, but this time it seems like it’s his own company that’s doing the probing. Musk has been investigated by Tesla over concerns that the automaker’s resources have been used inappropriately in the creation of a huge glass home for the boss.

That’s according to The Wall Street Journal, which was tipped off about ‘Project 42,’ a construction program Tesla execs feared wasn’t a legitimate Tesla project but a plan to build a private residence close to the Austin Gigafactory. Bloomberg reported last year that Tesla had already investigated the purchase of millions of dollars worth of special glass last year to work out whether the materials were for Musk’s personal use. But the existence of Project 42 wasn’t revealed at that time.

Different renderings seen by the WSJ showed the building as either designed in the shape of a twisted hexagon or a glass cube, a bit like the Apple store on New York’s Fifth Avenue. The presence of bedrooms, bathrooms, and a kitchen suggests that this is definitely not somewhere conceived to store a load of Cybertruck parts.

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Site of Project 42 is close to Austin Gigafactory in Texas

Although policies on spending by top execs differ from company to company and may include expensive luxuries such as the use of a jet, it’s unusual for boards to agree to the use of corporate cash to pay for private homes, the WSJ explains. But if part of the same building is used for work purposes it may be allowed, it adds, noting that Tesla’s audit committee has to review and approve any transaction above $120,000.

Project 42 would certainly top that figure and, if it really is a house for Musk, signals a change in what the CEO needs from a living space. In 2021 Musk wrote on Twitter that he has been living in a $50k house in south Texas for the past two years.