Brandon · South Dakota

Four households. Twenty acres. Leave indecision behind.

A feasibility brief · Prepared by Tom Wullstein · July 2026
The numbers below
The Entry
$673,000
All-in for the base house — five acres, 2,400 square feet, three bed two bath, garage, and everything under it. Four levels, up to $1.5M. All of them further down.
The Structure
Thermal mass
Reinforced concrete wrapped in continuous insulation. Thirty to fifty percent lower energy bills, EF5-range wind resistance, and a house that coasts for days without power.
The Builder
One of us
Tom runs it as general contractor. That is where the savings on this page come from — no builder markup, and four houses buying as one account.
01 — The Land

Four miles outside Brandon

Twenty acres of rolling ground carrying four building eligibilities, sold as one offering. Good elevation, real views, and the Brandon Valley school district. It has been listed since January and it will not sit forever.

20
Acres total
Five acres each after the split
4
Building eligibilities
The reason this parcel exists as an opportunity
$800k
Asking price
$200,000 per household
~12 mi
To Sioux Falls
Rural, not isolated — the whole point

Three to four miles from both Minnesota and Iowa. Minutes to Brandon, twenty to downtown Sioux Falls. Beaver Creek Nature Area and the Big Sioux rec area are close enough to walk a dog in. Deer, turkeys, and pheasants are already living there.

The elevation is the thing. Gently rolling ground with a low draw running through it means every lot can have a view, the houses can sit on the high ground where they belong, and there is somewhere obvious for water to collect.

02 — Why Together

Four at once, built by one of us

Nobody here needs economies of scale explained. Tom runs it as general contractor — he is the least employed of the four, which is the qualification that actually matters. No builder markup, and four houses buying as a single account.

One mobilization instead of four for every piece of heavy equipment. One materials order for concrete, ICF block, lumber, windows, and roofing. One structural plan set. One road spur and one power extension, split four ways. Between us we already own a fair amount of the iron this needs.

On the base house that comes to $145,000 — roughly $63,000 in builder markup we do not pay, $57,000 in volume and mobilization, and $25,000 in sitework we share. It scales with the house: the largest level saves close to $390,000.

And the reason that isn't money

Every one of us is in the same decade of life. Parents who will need to be closer. Kids who will need somewhere to land that isn't a childhood bedroom. Four families solving that problem separately, in four different subdivisions, twenty minutes apart.

A suite is expensive as an addition and awkward as an afterthought. Designed in from the first line, on land we already control, with the engineering split four ways — it is the cheapest it will ever be. It is an option below, not an assumption.

03 — Thermal Mass

A wall that stores weather
instead of transmitting it

Six inches of reinforced concrete poured between two continuous layers of foam. Not a wall with insulation stuffed in it — a wall that is insulation, wrapped around structure. Everything else on this page follows from that decision.

An ICF wall rates R-25 to R-30+ against R-13 to R-21 for wood frame. That comparison is already favorable and it still misses the point twice.

No thermal bridging. A stud wall loses heat through every stud — a bridge to the outside every sixteen inches, floor to ceiling, around every window. Insulation only works where it is continuous, and in a stud wall it never is. An ICF wall has none.

The mass itself. Oak Ridge National Laboratory measured the thermal mass effect as worth the equivalent of another R-5 to R-9 on top of the foam. Concrete absorbs heat slowly and gives it back slowly, so the wall flattens the swing instead of passing it through.

And it does not leak. Air infiltration is a dominant heating load here, and wind is the thing we have most of. A monolithic concrete wall is effectively airtight — no wind washing through the insulation, no cold corners, no draft down the hallway in February.

WALL SECTION EPS CONCRETE EPS rebar OUTSIDE INSIDE
February, power out, −10°F outside INDOOR TEMPERATURE OVER 72 HOURS · MODELLED 70°60° 40°20° −20° 32° — PIPES AT RISK 0h12h24h 36h48h60h 72h OUTDOOR −10° ~44 h wood frame crosses ICF · 52° WOOD FRAME · 23° ICF Wood frame
Illustrative, not measured. Modelled decay for a 2,400 sf house with heat lost at hour zero, −10°F outdoors, no wind. Real numbers depend on air-sealing, glazing, and how many doors get opened. The shape is the point: a conventional house dumps everything it had within a day because everything it had was in the air. A massive, airtight house coasts — the concrete has been storing heat all winter and gives it back over days. Add the solar-and-battery package and the outage stops registering as an event at all.

What you actually get for it

Energy30–50% lower
Continuous insulation with no studs bridging through it, plus mass that flattens the daily swing. It compounds every year you own the house, and it grows as utility rates do.
Comfortno cold spots
No drafts, no cold outside wall, no room that is always four degrees off. The mass holds the whole envelope at one temperature. This is the thing people notice first and never stop noticing.
QuietSTC 50+
The constant prairie wind noise simply is not in the house. Neither is the road, the neighbor's equipment, or a storm at two in the morning. People consistently describe it as unnervingly silent.
Storms200+ mph
Wind speed is the wrong number. Buildings fail from debris, not pressure — a two-by-four at a hundred miles an hour goes through a stud wall and out the far side. It hits six inches of reinforced concrete and falls down.
Outagesdays, not hours
See the chart above. A conventional house at ten below is uninhabitable within a day. An ICF house is still comfortable at seventy-two hours, and its pipes never get close to freezing.
Pestsnothing to eat
There is no stud cavity — no hollow wall for mice to run, no void for wasps or ants to nest in, and nothing termites recognize as food. The most common entry route into a house simply does not exist.
Mold & rotno organics
Foam and concrete are not food for anything. No cavity where warm air meets a cold surface and condenses. The failure mode that quietly destroys conventional walls is not available here.
Fire4-hour rating
A grass fire on the prairie stops at the wall. So does a fire inside — an ICF wall between the garage and the house is a genuine barrier, not a layer of drywall.
Air qualityfiltered, not leaked
A tight envelope means air comes in through a filter you chose, not through gaps you didn't. Harvest dust, chemical drift, and pollen stay outside — which in this county is not a small thing.
Smaller mechanicalslower first cost
A load calculation on this envelope comes back needing meaningfully less furnace and less air conditioner. Smaller equipment costs less, cycles less, and lasts longer. Part of the ICF premium is paid back before anyone moves in — and it makes geothermal much cheaper, which is below.
Insuranceask your carrier
Several carriers discount concrete construction and impact-rated roofs. Worth one phone call each before anyone assumes the credit is nothing.
Durabilitygenerational
Nothing in the wall rots, settles, warps, or off-gasses. This is a structure your kids inherit rather than replace.
04 — The Houses

Four levels

Every one is a full ICF envelope with an attached garage, slab on grade with radiant floor, standing-seam roof, and deep south glazing. What changes is scale and finish. Prices are structure and sitework — land is a flat $200,000 on top.

The Wullstein
Level one
2,400 sf3 bd / 2 ba
$473,000Structure + sitework
All-in with land $673,000
  • 2,400 sf ICF envelope, single level
  • 800 sf attached garage
  • Open main, 3 bed / 2 bath
  • Slab on grade, radiant floor
  • Hardened interior core
  • Well, septic, drive, grading
Retail $618,000 — save $145,000
The McAreavey
Level two
3,200 sf4 bd / 3 ba
$608,500Structure + sitework
All-in with land $808,500
  • 3,200 sf ICF envelope
  • 900 sf attached garage
  • 4 bed / 3 bath
  • Room for a real office and a real pantry — the two things everyone regrets
  • Hardened interior core
  • Well, septic, drive, grading
Retail $791,500 — save $183,000
The Scherer
Level three
4,200 sf4 bd / 3.5 ba
$819,900Structure + sitework
All-in with land $1,019,900
  • 4,200 sf ICF envelope
  • 1,100 sf attached garage
  • 4 bed / 3.5 bath plus bonus
  • Elevated finish throughout — better glazing, millwork, and mechanicals
  • Hardened interior core
  • Well, septic, drive, grading
Retail $1,062,800 — save $242,900
The Tysdal
Level four
5,400 sf5 bd / 4.5 ba
$1,300,000Structure + sitework
All-in with land $1,500,000
  • 5,400 sf ICF envelope
  • 1,400 sf heated, finished garage
  • 5 bed / 4.5 bath
  • Premium throughout — the money goes into windows, stone, millwork and mechanicals rather than square footage
  • Great room that holds everyone at Thanksgiving
  • Hardened interior core
Retail $1,688,400 — save $388,400

Four levels is a starting grid, not a catalog — and the names are just so we can talk about them without saying "the second one." Nobody's house is going to look like the neighbor's. Different footprints, different rooflines, different orientation to the view. The shared plan set is structural engineering and wall assemblies, which is where the money is. What it looks like from the road is yours.

05 — Add-Ons

The part worth thinking about

Some of this goes on your lot and you pay for it. Some of it goes on shared ground and splits four ways — and that is where the compound stops being four houses and starts being a reason to do this.

On your lot

Your cost, your call

Guest & In-Law Suite

650 sf attached, private entry, kitchenette, full bath, zero-step throughout and framed for grab bars. Works for a parent now, an adult kid at twenty-four, and a renter after that.

$133,250Added to your house

Geothermal

Ground-source heat and cooling. Drilling is most of the cost, so four houses on one drilling contract is where this gets interesting — and the ICF envelope cuts the load about forty percent, which shrinks the bore field, which is the expensive part.

$17,000–34,000Your share, by house size
Alone it runs $21,000–43,000

Off-Grid Package

8 kW array and 20 kWh of battery. On an envelope this tight it covers most of the year. Pairs with the thermal mass to make a multi-day outage a non-event rather than an emergency.

$38,000Solar only, no battery — $24,000

On shared ground

Split four ways

The Shop

Sixty by eighty, insulated, four bays and a mezzanine. Equipment, the boat, the camper, and enough bench to actually finish a project. None of us would build this alone; all of us would use it.

$51,600Your share
Built cost $206,400 · 4,800 sf

Pool House, Gym & Hot Tub

Enclosed year-round pool, hot tub, and a proper exercise room — rubber floor, racks, and mirrors, not a treadmill in a corner. In this climate an outdoor pool is a four-month asset and an eight-month regret.

$107,500Your share
Built cost $430,000 · 1,500 sf

The Pond

Half an acre in the low draw, dug deep enough on one end to overwinter fish. Stocked for bass and bluegill, aerated against winterkill. Skating in January, a dock in July. Scherers have already built one — that experience is worth more than the line item.

$12,000Your share
Built cost $48,000 · ~0.5 acre, stocked

Sport Court

Thirty by sixty, post-tensioned concrete with an acrylic surface. Pickleball striped over basketball, lit for evenings, fenced so nobody walks to the neighbor's for a ball.

$12,000Your share
Built cost $48,000

The Practice Hole

A real green with a cup and a flag, a tee back far enough to need a club you'd actually carry, one bunker to make it mean something, and mowed approach across the shared ground.

$10,500Your share
Built cost $42,000 · 1,200 sf green

What splitting it four ways actually does

The shop, the pond, the court, and the practice hole — all of it, built properly:

$86,100 a household

Add a share of the pool house, gym and hot tub and it is $193,600.

None of these is a thing a person builds on a five-acre lot by themselves. Divided by four they stop being extravagant and start being obvious — which is the entire argument for doing this together rather than separately.

A note on the geothermal

Shared ground loops are a real and established thing — utilities are building networked geothermal for whole neighborhoods, where houses trade heat with each other through a common loop and the whole system runs at five or six hundred percent efficiency.

At four houses spread across twenty acres, the piping to connect us would probably cost more than the sharing saves. What is unambiguously worth having is the other half: one drilling rig mobilized once instead of four times, one contract's worth of bore footage at volume pricing, and one designer laying out four systems.

There is a version that is better than that. If the four build envelopes sit reasonably close together on the ridge, a genuinely shared bore field comes back into play — and that is a siting decision we would be making anyway, right at the start, for free. Worth an hour with a geothermal designer before anyone picks a house location.

On all these numbers. Per-square-foot bands come from published 2026 regional cost data — sources at the bottom. The per-household model built on them is an estimate, not a quote. Nobody has walked this ground with a tape measure. Treat these as the shape of the decision and expect real bids to move every line ten percent one way or the other.

06 — Sequence

What happens when

Assuming a decision this fall. Ground freezes in November and does not forgive optimism.

Now — August 2026

Confirm the four

Everyone reads this page and says yes, no, or not at this number. Nothing else can be scheduled until we know whether this is four households or two.

September 2026

Diligence and soils

Perc tests and a soils investigation — which answers the septic question and the pond question in one trip. Confirm the building eligibilities in writing. Co-op line-extension quote. Attorney sets up the holding entity. Walk the ground together and pick lots.

October – December 2026

Acquire and plat

Close as the entity. Submit the plat to Minnehaha County. Plat approval is measured in months, not weeks — this is the long pole and it runs through winter, which is the right time for it to run.

Winter 2026 – 27

Design and bid

One structural plan set, four different houses on it. Bid every trade as a four-house package — this is where the volume discount is either captured or lost. Order long-lead items: windows, ICF block, roofing.

Spring 2027

Break ground

Road spur, power, wells, septics — all four at once, one mobilization each. The pond and the shop pad go in with the same equipment while it is already on site, which is most of why they are cheap.

Late 2027 – Spring 2028

Occupancy

Staggered completion. First house done carries the punch list lessons into the last three, which is worth more than it sounds.

07 — The Name

"The Compound" is a working title

It got us this far and it is going to alarm somebody's mother. Candidates below — bring your own, we vote at the first meeting.

Section 4

Four eligibilities, and the survey unit rural land is measured in. Dry and confident.

Beaver Creek Commons

For the adjacent nature area. Place-rooted, warm, reads like a real development.

The 264 Project

From 264th Street. Understated, easy to say, works as a codename now and a name later.

Windbreak

The shelterbelt on the north line, and what four households are to each other.

Quarter Quarter

County zoning language for the forty-acre unit that grants a building right. An inside joke that becomes a sign.

08 — What I'm Asking

Dream big. Keep an open mind.

Nothing on this page is fixed. The sizes are a starting grid, the add-ons are a menu nobody has to order from, and every number will move once somebody walks the ground with a tape measure. I built this to give you something real to react to, not something to agree to.

So react to it. Tell me the house is too small or the pond is the only part you care about or that you want a shop twice that size. Tell me the whole thing is crazy. All of that is useful. Silence is the only response that isn't.

"Indecision is worse than no decision."
— someone on this list, repeatedly

He's right, and it is the reason this page exists. Four of us have been half-joking about this for a while. The land is real, the number is real, and it has been sitting on the market since January. At some point half-joking becomes a decision by default, and default is the one option none of us would have picked.

Come look at it with me. Bring the spouses. Then tell me what you actually want — and let's find out whether the four of us can build something none of us would build alone.