LEGO reveals its internal rules for modular buildings

22/10/202412/03/2026 Chris Turner-Wharfe 3215 Views 0 Comments

The LEGO X-Mansion’s designer has revealed the three internal rules that the LEGO Group abides by for any and all modular buildings.

We’re living in a golden age for modular building collectors at the moment, as the LEGO Group has expanded its template beyond the LEGO Icons range across themes including Marvel, NINJAGO, and Chinese Traditional Festivals. But what makes a building modular in the first place? That’s the question answered by Justin Ramsden, the designer behind 76294 X-Men: The X-Mansion.

It turns out there are three golden rules for an official LEGO modular building, and the latest LEGO Marvel set ticks every single one of those boxes. One of them is pretty obvious to anyone paying attention, sure – but the others are maybe not quite so blatant. Keep reading to learn the LEGO Group’s internal rules for modular buildings, as Justin revealed to MiniSuperHeroesToday.

1 – The sides must have pin-hole connections

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Let’s get the most obvious one out of the way first: modular buildings all need to connect to one another using Technic pins and bricks with pin holes. The LEGO Group has been using these since 10182 Café Corner debuted all the way back in 2007, and they’re what allow the Icons modular buildings to snap together not only with each other, but with modular buildings from other themes too.

The X-Mansion features pin-hole connection points on either end of its building, allowing city builders to sandwich the set into your superhero street (if you so desire). The set apparently also accounts for connecting to 76178 Daily Bugle, which – as it comes in the box – doesn’t line up with other buildings, as one of its 1×2 pin-hole bricks is 10 rather than nine studs away from the edge of the baseplate.

2 – The middle floor must be repeatable

The LEGO Group’s second rule for modular buildings is that ‘the middle floor has to be repeatable’, says Justin. That’s a concept that again goes all the way back to 10182 Café Corner, as the LEGO Group specifically advertised the potential to buy multiple copies and stack the second floor of its hotel all the way to the Moon.

This is another rule that 76294 X-Men: The X-Mansion obeys, with its second storey able to be repeated indefinitely (with perhaps a little tweaking to remove the balcony if you so desire, as we’ve demonstrated here). But even if you leave it as it comes in the box, it is indeed possible to slot additional floors on to the X-Mansion, so it ticks that box easily.

3 – It must have some form of staircase

Here’s one you might not have been aware of: every LEGO modular building must apparently have some sort of staircase to allow minifigures to reach its upper levels. But this actually does go back to 10182 Café Corner too, as while that original modular building didn’t include an interior, it did still incorporate a staircase for its characters to ascend to its empty rooms.

Other modular buildings since have found novel ways to climb to their higher storeys, such as the fire escape around the back of 10185 Green Grocer (although that set does include staircases too), while some fall back on the regular pre-fab LEGO staircase piece, like 10246 Detective’s Office. And then there’s the skyscraper that is 76178 Daily Bugle, which instead incorporates a non-functional elevator in lieu of a staircase.

76294 X-Men: The X-Mansion duplicates that approach with its own elevator, which Justin points out both leans into the ‘stackability’ of the mansion’s middle floor, and also makes the entire building wheelchair-accessible for Professor Xavier.

Next time you’re wondering whether or not a LEGO set should be classed as a modular building, whether for your own collection or just in general, the first stop should probably be checking if it ticks all these boxes…

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76294 X-Men: The X-Mansion launches on November 1 for LEGO Insiders, and November 4 for everyone else, for £289.99 / $329.99 / €329.99. Hit the links below for more on the latest LEGO Marvel modular building and its exclusive gift-with-purchase.

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