Why Don't Southern Homes Have Basements?
Northerners are mystified that Southern homes don't have any space underground, and vice versa. So, uh, what's up with that? We delve deep into history and data to try and figure it out.
Earlier this year, I asked Rabbit Hole readers if they had any questions they wanted me to answer. David Gilman posed a twist on one that Southerners have been asking for a very long time:
I don’t know any geotechnical engineers but maybe you’ll meet one at a cocktail party. Piedmont houses don’t have basements because of the thick clay soil. However, in engineering, rarely is the answer “this is impossible” but is instead “this is out of your budget.” If you had unlimited money to sink into an unremarkable suburban North Carolina home to build a basement what would the design look like, what is the ballpark cost and what geotechnical forces does your design have to overcome?
David’s question leads to a bigger one: Why don’t Southern homes, in general, have basements? As an Ohioan, everybody I knew had one. It was weird if you didn’t. Down here, it’s weird if you do.
This question is so basic that you’d think that SEO vultures would be all over it. Which they are: A Google search for “why southern homes don’t have basements” brings back a lot of results, many of them from traffic-hungry home builders who give answers that seem to be grounded, largely, in anecdote or personal experience. We don’t have basements because of the climate. Or the soil. Or the cost. Or the water table. All of these things could be true, and yet most of those theories aren’t rooted in research, study, or data. I contacted the NC State School of Design, and the faculty there weren’t aware of any academic studies or research on that specific topic.
The Southern non-basement thing is a definite vibe. But I went looking for hard numbers and data so see if I could back up that feeling with facts. It sure feels like homes up north have a lot more basements, but how many more? Has anything changed over time? And, as David asks, if you demand that a builder adds a basement to your house, how much more is that going to cost you?
Strap in. Here’s what I got.
Most Northern houses have basements. Most Southern houses do not. Duh.
It will probably not shock you to learn that yes, basements are a largely Northern thing. But you may not know just how wide the gap is between regions.
That U.S. Census data covers all basements, including partials and walk-outs. And yes, the frost line—the line above which the ground can potentially freeze—is a big factor. “In [the Northeast and Midwest], basement foundations can add additional finished floor area to a home at a marginal increase in excavation cost because the bottom of the foundation wall footing is required to be at or below the frost line,” reads a 2015 report from researchers at Northern Kentucky University. In parts of the South, the frost line might only be few inches deep. In parts of Maine and Minnesota, that frost line might be five to eight feet below the ground.
A closer look here shows a few things: In general, basements have been in decline nearly everywhere over the last 20 years (except for the West). There are two potential culprits: The price tag, along with better technology. “If … frost-protected shallow foundations are increasing in usage,” reads the Northern Kentucky report, “the cost savings could be substantial enough for new home owners to forgo the inclusion of the traditional basement.”
One more thing that may not be clear here: More than half of all of the new single-family homes built in the United States in 2022 were built in the South. That’s a lot! And since hardly any of those homes have basements, it sort of drags the whole basement-industrial complex down with it. In fact, only one out of every 20 new Southern homes is built with a full or partial basement. But! That wasn’t always the case. Fifty years ago, one in every five Southern homes was built with a basement. So, what did everyone decide to do instead?
We got more slabs in the South than the undertaker
In the South, the basement is disappearing, but so is the crawl space. “In the South Region, a high water table can make a slab-on-grade the most logical foundation choice,” the NKU report stated. “Additionally, a shallower frost line requirement in the warmer climates can also make a slab foundation the most cost-effective option.”
As you can see, slabs have long been the number one choice for Southern foundations. Now, they’re practically the only choice. Basements have largely vanished. Why? “From my perspective and experience, it’s generally a cost issue,” says Josh Breed, a Rabbit Hole reader and civil engineer who previously designed single-family home developments around Charlotte. Home builders want to maximize profits by minimizing costs. Slabs are cheap. “Basements are are usually some of the first things that are excluded from a project,” he says.
There’s another factor here: Scale. “These large developers have crews that they hire out. And so it’s easier for them to build the same product over and over again,” says Breed. “If you’ve got 100 homes in a subdivision and five of them have basements, it throws a wrench into things.” Hence, steep lots that seem like good candidates for walk-out basements are often regraded to make them slab-worthy. Still there are limits. “With what I've seen, the only places we've designed lots for basements have been where the slope falls away at a fast enough rate that it would be prohibitively expensive to bring in fill dirt to level the lots, especially if that fill dirt has to come from off-site,” he says. “Anything greater than 5-10% grade would usually get a basement or crawl space if we couldn't flatten it. Since the ground is already sloping away on a hill, there's even less material for the contractor to excavate.”
Lifestyles of the Rich and Basemented
On steeper hillsides, basements might be more economically feasible if not wholly necessary. So by that token, is an unnecessary basement a luxury item? Or, are they at least a good investment? They seem to be in London, where a lot of people are asking for permission to build basements underneath existing homes. You get more living space, and you also might make a bigger profit when the home sells. Some estimates say that every British pound spent on a basement could add two pounds to the home’s value.
That’s also possible over here, too (although it’s going to cost you tens of thousands of dollars to jack your whole house up, and then you still have to dig out a big hole). But even if you build a basement when you build your house, it’s still going to cost you. One home builder who wrote a book about affordable construction states that building a full basement can add 8% to the total cost of a new house. HomeGuide did a survey and found that the average price to build a slab foundation was around $6 a square foot. A full, unfinished basement cost 5.5 times more.
Almost half of that cost, 45%, was for excavation, while about a third went toward pouring the concrete walls (block-walled basements are more expensive because they require skilled labor). There are a ton of variables in that analysis, which is where you ought to go if you have more specific questions.
So does that make your home worth more? Sure! But how much more is, again, an imperfect calculation with a lot of variables. There is one objective(ish) way to tell: Property assessors. Whenever local officials decide to recalculate the tax value of every piece of property in their county, they have to come up with some sort of system that helps them figure it out by relying on in-house data versus in-person visits (which would take forever). Most of it’s based on square footage, and different types of uses are worth either more or less.
So, take Lincoln County, North Carolina, which went through a revaluation in 2023. There are some flat-rate add ons (a boat slip, for example, adds $30,000 to a property’s tax value), but most of it is based on square footage. In Lincoln County’s estimation, an unfinished basement is valued at $24 more per square foot than a crawl space (which is the county’s baseline standard). It’s worth $28 more than a slab. The value goes way up when you finish the basement ($57/square foot), and if that finished basement is a walk-out ($70/square foot). By my back of the napkin math, if you’re going to really add some value to your new home by going with a basement, you also have to be prepared to pay more in taxes and make it look awful nice down there.
So, how much would a superfluous basement run you, Mr. and Mrs. Moneybags?
If you want a basement and you have the money, there’s nothing stopping you from building one. Even some of the old-school issues with basements—waterproofing, drainage, ventilation, and radon—have been solved with newer technology and techniques. And, yes, if you’re looking to buy an existing house in North Carolina, it’s not hard to find one with a basement on Zillow. But! Most of those seem to be finished walk-out basements, which offer the best return on investment for homes that are already built into some sort of hillside.
Just because you can build a straight-up Wayne’s World-style basement in the South doesn’t actually mean you will. “I’ve lived in the South my whole life, and I’ve really only ever seen walk-out basements,” Breed says. And during his time as a builder, nobody ever demanded a basement that wasn’t absolutely necessary.
So, to answer David’s question: By those calculations above, a basement for a house with a 1,500 square foot first-floor would run you, potentially, around $50,000, far more than a slab. You’d probably pay extra to excavate the heavy clay soil, you’d need to make sure you walls were extra thick, and you might need some really great drainage if the water table’s fairly high in your area. You may also have to install a Pittsburgh Toilet. But all of it is gonna cost you a big chunk of change. So there you go David. That’s my best estimate. If you can go ahead and cut me a check, I’ll grab my shovel and get started.
NOTE: I did the very best I could here, but I am not a contractor or a builder. If you are and have something to add, I encourage you to do so! If you have data that I’m not privy to, even better. I am also taking recommendations for the best basement futons that’ll really tie the room together.
we have basements in the mountains of NC, lots of houses are built on the sides of hills. I know the dirt up there is way different because now I live in Chatham County and have tried to dig a hole.
I appraise residential real estate in NC and can say I don't have a whole lot to add, this piece did a really good job of laying it out. Guy I learned under always said "we don't dig basements down here" i.e. what you were saying, we will build walk-outs where the topography dictates it and/or when someone wants but don't dig out walk-ups, by and large. Broadly speaking my view is that with new stuff, it comes down to cost (excavation) and scale as you said. In the past, and I don't have hard data for this, it seems that in so many cases the raw land around here was inexpensive enough that it made more sense to build more out and up with bigger lots than down.