Real estate investing can be a great way to earn a passive income. Once you've done your homework, invested in a property, and found someone to pay for its use every month, you can sit back and enjoy that steady check coming in.

Of course, most buildings will require a significant amount of repair and maintenance over time, so you would have to figure in the time and money required to handle that. And if you're doing all that yourself, it's not really passive income, so you might need to hire a property manager.

But what if your real estate investment didn't come with any buildings you need to worry about? That could be a huge plus for your bottom line. Let's explore a few of the less common ways you can earn a passive income with real estate, building-free. With any of the following options, you can either invest directly yourself or with real estate investment trusts (REITs) that hold these types of properties.

Two people in a corn field, one pointing into the distance.

Image source: Getty Images.

Vacant land

Most investors considering real estate imagine a building of some sort factoring into the equation. But there are several ways you can make passive income with vacant land. It could be worth checking out if you can find a good deal on a large plot in the right area. There's a high probability its value will only increase as demand grows, and there are several potential ways you can use it to make passive income.

Your options will, of course, depend on the size of the plot, the characteristics of the land, its location, and what the zoning will allow. You would want to go into it with an idea of what you'd like to do and make sure that would be an option with the land you're considering. Possibilities include turning the property into a hunting lease or leasing it out as farmland. You could also plant timber on part of the property you aren't leasing and either sell the timber when the time comes or simply have more value in the land if you choose to sell down the road.

Blank billboard in field with blue sky and mountains in background.

Image source: Getty Images.

Billboards

Advertising has come a long way over the years. We've even talked about how the advertising potential of the metaverse could impact real-world real estate. But the classics are classics for a reason, and that certainly holds true for billboard advertising.

While TV and radio stations can be changed or silenced, traffic creates a bit of a captive audience for a billboard message. And there are situations where nothing else would quite do -- like a massive, mouthwatering billboard photo of food right before the exit where drivers can enjoy that meal.

To lease out a billboard, you would first make sure you would be able to get a permit for a billboard in the area you're interested in. If so, you would get a long-term ground lease on the small piece of land where you would erect the billboard. Of course, if you already own property where a billboard might work well, that's even better. Finally, put up your billboard and find an advertiser. This could be as simple as putting your contact info on the billboard.

Three mobile homes in a row with a palm tree in front.

Image source: Getty Images.

Mobile home parks

When you think of a passive real estate investment where you collect rent for the space where people live, you probably think of single- or multifamily homes. But with the average mobile home park, you're simply renting out the lots your residents' own mobile homes sit on. When you rent out a home you own, the maintenance and repairs involved mean you'll need a property manager if you want a truly passive investment.

But with a mobile home park, your only concerns are maintaining the road within the park and any outdoor common areas and collecting rent. The residents are even responsible for maintaining their own yards. And with housing affordability becoming an increasingly pressing concern, now could be a great time to invest here.

Should you consider an unconventional real estate investment?

While these three methods for generating passive income with real estate are all unconventional, it's important to note that none of them are new or untested. They've all been generating passive income for investors for many years. They simply don't generate the attention that the more traditional real estate investing avenues, like renting out homes or leasing out commercial buildings, do.

If any of these methods of generating passive income have piqued your interest, they're well worth exploring further and could be a great way to diversify your portfolio.