The Walipini
A semi-subterranean passive-solar greenhouse — the most complex, most expensive, and most resilient Grow rig in the entire Ark.
The Walipini ("place of warmth" in Aymara) was developed by the Benson Agriculture and Food Institute at Brigham Young University from indigenous Bolivian designs. The principle is elegant: dig a 6–8 ft pit, cover it with angled glazing oriented toward the winter sun, and let the surrounding earth — which stays at a constant 50–60°F below the frost line — provide free thermal stability. Add water barrels as supplemental thermal mass, and you get a structure that grows tomatoes through January in zone 5. Where the Porch Garden extends the season by 4–8 weeks, the Walipini eliminates the off-season entirely. This is the rig that makes household food sovereignty possible in cold climates, and the rig that integrates more domains than any other — Well (Sky Well from glazing, Deep Reserve cistern), Power (The Burn for supplemental heat), Loop (The Sanctum compost for fruit trees grown inside), Signal (Sentry monitoring, Actuator vent control), Forge (The Mill for lumber), Shield (The Hedge as windbreak). Build this rig last because every rig it Feeds with is already documented. Build this rig only when you're ready to commit to a structure that should last 30+ years.
① Choose your build
Every build below is complete on its own. Pick the one that fits your space and budget.
Compact WalipiniENTRY$2,500–6,000
Small-footprint Walipini for a single household or single experimenter. Hand-dug or with a mini-excavator. Glazing is a single-panel slope. No interior structural posts. Simplified ventilation. The proof-of-concept scale before committing to the canonical 12×20.
Hand-digging at this scale is feasible (3–4 weekends with two people). 8×10 is the smallest practical size — anything smaller becomes awkward to work in and doesn''t justify the construction effort.
An 8×10 × 6 ft pit is ~18 cubic yards of soil — a one-day mini-excavator job, or a multi-weekend hand-dig with shovels and a wheelbarrow. The hand-dig option is what makes Path A accessible to households without contractor budgets.
At Path A scale, the lighter / cheaper wall systems are practical. Earthbag is the lowest cost ($300–500 in materials) but most labor-intensive. Treated lumber retaining walls are fastest but have a 15–20 year lifespan.
Single straight slope (not stepped or peaked) is the simplest geometry. 6mm is acceptable at this scale because the smaller air volume warms quickly and cools quickly — insulation matters less than at Path B scale.
At ~60 sq ft of glazing for an 8×10 build, the 2–3 gal-per-sq-ft rule says 120–180 gal of mass — three to five barrels along the back wall.
The minimum viable vent set. Even at this scale, automatic openers are non-negotiable — without them the Walipini overheats catastrophically on sunny days.
Canonical WalipiniRECOMMENDED$6,000–15,000 (DIY) to $25,000+ (contracted, engineered)
The standard recommended size — 12×20 ft, 240 sq ft. Excavator-required excavation. Structural engineering recommended even when not legally required. Full passive-solar geometry, automatic ventilation, integrated thermal mass, drainage system. Year-round production for a family of four. Pricing in this manifest is for Path B; smaller Path A and larger Path C scale this manifest accordingly.
Verify level ground, sun exposure (no winter shade from trees / structures from 9am–3pm), drainage flow direction, existing utilities (call 811 before digging).
if you prefer… (1)
Critical: dig a 6 ft test hole and observe water table after 24–48 hrs. Water table must remain at least 5 ft below your planned floor. Heavy clay soils require more drainage engineering; sandy soils are ideal.
A 12×20 × 7 ft pit moves ~62 cubic yards of soil. Save the spoil pile — it gets bermed against the north, east, and west walls for additional insulation. Hand-digging at this scale is impractical (3+ months for one person).
if you prefer… (1)
Mound spoil 2–3 ft deep against the north, east, and west walls after walls are built. This is the second insulation layer; it nearly doubles thermal performance.
Frost depth: 12" in zone 8, 24" in zone 6, 48" in zone 4. Footer must extend below this depth or wall heaves. Pour concrete footer 8" thick × 16" wide all the way around the perimeter.
The standard, code-friendly choice. Stack courses to ground level (or ~12" above) on three sides; the south side stops at the glazing-frame interface. Fill cells with concrete + rebar for structural integrity.
if you prefer… (4)
Apply to the outside of the walls before backfilling. Critical: without this, walls absorb groundwater, lose insulating value, and eventually leak. The drainage mat (dimpled plastic) directs water down to the French drain.
if you prefer… (1)
R-10 insulation on the exterior of all below-grade walls. XPS only — not EPS — because EPS absorbs water and loses R-value. Goes between the waterproofing and the backfilled soil.
if you prefer… (1)
Gravel-and-paver: cheapest, allows drainage, easy to modify later. Concrete slab: most permanent, easiest to clean, but adds cost and complicates future drainage work. Pavers preferred for most home builds.
Non-negotiable. Wraps the outside of the footer, daylights downhill or to a dry well. Without this, the Walipini becomes a swimming pool during heavy rain. The single most important system for long-term success.
Catches condensation drips, irrigation overflow, and any water that does penetrate. Sump pit can hold a small pump for emergency removal.
if you prefer… (1)
The angled glazing surface is essentially a giant rain collector. A 12×20 ft Walipini with a 30° glazing slope sheds ~150 sq ft of horizontal-projected catchment. Pipe directly to a Sky Well rain barrel or cistern. The Walipini is one of the largest single contributors to Sky Well capacity in the entire Ark.
8mm gives R-1.8 and 80% light transmission with 15+ year lifespan. Better insulation than 6mm; the Walipini stays in service longer than the Porch Garden, justifying the upgrade. UV-protected side faces the sun. Flutes run vertically.
if you prefer… (4)
The single most important geometric decision. For zone 5–6 (latitude ~40–45°N), aim for 50–60° glazing angle — much steeper than a typical greenhouse. This perpendicular-to-winter-sun angle captures maximum light when you most need it. Shallower angles work in tropical / subtropical zones; steeper angles required at higher latitudes.
Wood frame supports the polycarbonate panels. Connectors must be hot-dipped galvanized or stainless — ordinary fasteners corrode rapidly in the high-humidity below-grade environment. Use H-channels between panels and U-channels on exposed edges.
if you prefer… (2)
Polycarbonate expands / contracts ~3mm per meter per 10°C temperature change. Holes drilled 2× the screw diameter; neoprene washers seal against water entry while allowing movement.
Caps the top of vertical flutes — sealed flutes grow mold inside the panels. Vented end caps allow moisture out while keeping dust / insects out.
Sizing rule: 2–3 gallons of thermal mass per square foot of glazing. A 12×20 ft Walipini with ~150 sq ft of glazing wants 300–450 gallons = 6–9 fifty-five-gallon barrels. Place along the north wall where they receive direct winter sun. Add 1 tbsp bleach per 10 gallons or 1 cup hydrogen peroxide per barrel to prevent algae.
if you prefer… (2)
Two options: maximize the north wall as additional thermal mass (paint dark, leave bare CMU), OR insulate behind the barrels to direct heat back into the growing space. Most Walipinis benefit from the latter — barrels alone provide enough mass, and insulation prevents heat loss into the earth.
Refresh annually. Black barrels with white interiors (line with white plastic) reduce algae while maintaining heat absorption.
Hot air rises and exits here. Total area: minimum 20% of floor area. For 240 sq ft floor, that''s 48 sq ft of total vent. Install at the highest point of the glazing or in the peak.
Cool air enters here, creating the chimney effect that drives natural ventilation without electricity. Often built as covered openings in the back wall connecting to a buried pipe that surfaces outside (preserves thermal envelope).
Non-negotiable. Same as Porch Garden — wax-cylinder, no electricity, 10–15 year lifespan, opens at adjustable temperature setpoint. Without these, the Walipini overheats catastrophically on sunny days even in winter.
if you prefer… (2)
Optional supplement for hot summers or when passive ventilation isn''t sufficient. Especially valuable south of zone 7.
The exhaust duct from a rocket mass heater (typically located adjacent to the Walipini in a separate small structure) routes through a cob / brick bench inside the Walipini before venting outside. The bench absorbs residual heat from the exhaust gases — mass radiates warmth for hours after the burn. This is the most resilient supplemental heat option. Burn wood from The Mill, store heat in mass, no electricity required.
if you prefer… (3)
Even passive Walipinis benefit from emergency thermal blankets during extreme cold (below 0°F outside). Drape over crops at sunset, remove in morning.
Raised beds prevent root contact with cold floor soil and elevate plant tops into warmer air zones. Lumber: cedar or pressure-treated. Stone: from local sources, doubles as additional thermal mass.
if you prefer… (3)
Same mix as Porch Garden, deeper for warm-season crops. Top with mulch.
Vertical growing maximizes the Walipini''s volume. Cattle panel arches between beds create cucumber / tomato tunnels. The walls themselves become trellises with attached cables.
The Deep Reserve cistern (Well domain) feeds water directly into the Walipini interior. Gravity-fed if cistern is uphill; small pump if not. Keeps water at moderated underground temperatures (50–60°F) — won''t shock plants like cold tap water.
if you prefer… (1)
One emitter per plant for vegetables; multiple per shrub or tree. Battery-powered timer or manual.
if you prefer… (1)
Backup for the drip system. Always functional.
The Walipini is the most sensor-rich rig in the Grow domain. Air temp at canopy, soil temp in beds, soil moisture in beds, optional CO2 (especially for fruiting crops in winter). All report to Ark Core via Meshtastic mesh.
The Actuator drives vent openers (electric override of the wax-cylinder backup), irrigation valves (zoned watering), and optional shade cloth motors. Most useful in summer (heat management) and during deep-cold windows (close vents at night, open in midday).
Family Farm WalipiniADVANCED$15,000–50,000+
Small-farm scale — 16×30 ft (480 sq ft) or 20×40 ft (800 sq ft). Engineered drawings required. Likely permitted as an agricultural structure. Multiple growing zones, aquaponics integration, fruit tree zone, propagation zone. Income-producing scale. There are no separate items to buy beyond scaling Path B; Path C describes the design and engineering decisions that scale-up demands.
At 480 sq ft+ most jurisdictions require engineered drawings even for agricultural structures. Engineer reviews wall load capacity, glazing wind / snow loads, drainage capacity, and access door egress. Budget $1,500–4,000 for full engineering review.
At Path C scale, you can dedicate space to differentiated zones: a warm humid zone for tropical and citrus; a cool humid zone for greens / brassicas; a dry zone for Mediterranean herbs and grain trials; a propagation zone with bench heating for seedling starts.
The Walipini''s climate-controlled space removes the winter heating dependency from the Living Shelf. Combined Walipini + Living Shelf is the most productive single growing space in the entire Ark. Allocate a 4×8 ft zone with reinforced floor for fish tank weight.
Path C scale enables small fruit trees inside the Walipini — citrus production in zone 6 becomes possible. Trees go in the largest planter or in the floor with extra-deep soil pocket. Receive Sanctum compost top-dressing (Loop Feed) for fruit-tree fertility.
At family-farm scale, the Walipini becomes the seed-start hub for the entire household plus surplus for sale. Bottom-heat propagation mats accelerate germination; supplemental LED lights extend the photoperiod for early-spring starts.
At Path C scale, expect to navigate the permit process formally. Many jurisdictions have agricultural exemptions that simplify the process if the structure is genuinely for food production. Some jurisdictions require ADU / accessory structure permits regardless. Resolve at Step 01 of the build sequence.
③ The Sequence
④ Reference Tables
Sizing & Geometry
The non-negotiable geometric decisions — get these right at design time, they're hard to fix later
| Element | Spec |
|---|---|
| Recommended size | 12×20 ft (240 sq ft) |
| Pit depth | 6–8 ft (mild climates 4–5 ft) |
| Long axis | East-West |
| Glazing direction | True south (N. hemisphere) |
| Glazing angle (zone 5–6) | Latitude + 10–15° (~50–60°) |
| Glazing angle (zone 8–9) | Latitude + 5–10° (~35–45°) |
| Floor below grade | 5–7 ft (water table 5+ ft below floor) |
| Berm against N/E/W walls | 2–3 ft of excavated soil |
Thermal Mass Sizing
2–3 gallons of thermal mass per square foot of glazing — black-painted barrels along the north wall
| Glazing area | Water volume needed | Barrel count (55 gal) |
|---|---|---|
| 100 sq ft | 200–300 gal | 4–6 barrels |
| 150 sq ft (12×20 std) | 300–450 gal | 6–9 barrels |
| 200 sq ft | 400–600 gal | 8–12 barrels |
| 300 sq ft | 600–900 gal | 12–18 barrels |
Ventilation Math
Total vent area = 20% of floor area; split between high exhaust (60%) and low intake (40%) for chimney effect
| Floor area | Total vent area needed |
|---|---|
| 100 sq ft | 20 sq ft |
| 240 sq ft (12×20) | 48 sq ft |
| 480 sq ft (16×30) | 96 sq ft |
| 800 sq ft (20×40) | 160 sq ft |
Insulation R-Values by Zone
Match insulation depth and glazing thickness to your USDA zone — under-insulating is the second most common failure mode after drainage
| Zone | Below-grade wall insulation | Glazing |
|---|---|---|
| Zone 3–4 | R-15 (3" XPS) | 10mm twin-wall (R-2.0) |
| Zone 5–6 | R-10 (2" XPS) | 8mm twin-wall (R-1.8) |
| Zone 7–8 | R-5 (1" XPS) | 6mm twin-wall (R-1.6) |
| Zone 9+ | Insulation optional | 6mm twin-wall (R-1.6) |
Cost Range — Path B (12×20 ft)
Component-by-component breakdown showing where DIY savings concentrate vs. where contractors are worth the cost
| Component | DIY low | DIY high | Contracted |
|---|---|---|---|
| Site / permits / engineering | $200 | $1,500 | $2,500 |
| Excavation | $500 | $2,000 | $4,000 |
| Walls + footer | $1,500 | $3,000 | $7,000 |
| Waterproofing + insulation | $400 | $700 | $1,500 |
| Drainage | $400 | $800 | $1,500 |
| Glazing + frame | $1,000 | $2,000 | $4,000 |
| Ventilation + auto vents | $200 | $500 | $1,000 |
| Thermal mass | $200 | $500 | $800 |
| Beds + soil + irrigation | $500 | $1,000 | $2,000 |
| TOTAL | $5,000 | $12,000 | $24,000+ |
The Three Rules
If you follow only three principles, follow these — they prevent every common Walipini failure
| Rule | Why it matters |
|---|---|
| 1. Permits first | A $40 phone call saves a $4,000 retroactive headache. Some jurisdictions classify Walipinis as agricultural and exempt; others require full structural permits and engineering. Resolve before excavating. |
| 2. Drainage is non-negotiable | No French drain = swimming pool. The single most important system for long-term success. Wraps the outside of the footer, daylights downhill or to a dry well. |
| 3. Build it once, build it right | A 30-year structure built in a hurry becomes a 5-year disaster. The patience isn''t just a virtue — it''s the design. Walls have to cure. Drainage has to be tested before backfilling. |
Crops by Season
The Walipini's claim to fame — every category of fresh produce, every month of the year
| Crop family | Growing window |
|---|---|
| Greens (lettuce, spinach, kale, mâche, arugula) | Always available |
| Tomatoes (cherry + slicer) | February–November |
| Peppers (sweet + hot) | May–October |
| Herbs (basil, parsley, chives, oregano, thyme) | Always available |
| Brassicas (broccoli, cauliflower, Brussels) | September–April |
| Cucumbers | Spring + fall |
| Citrus (zone 6+ inside) | December–March harvest |
| Strawberries | April–September |
⑤ The Echo
The fundamental insight that makes the Walipini work. Below the frost line, soil temperature stabilizes at 50–60°F regardless of surface conditions. There''s an 8-week thermal lag — the soil is at its warmest in October, its coldest in April. By placing your growing space inside this stable thermal zone and letting the surrounding earth function as a giant thermal battery, you eliminate the energy cost of growing year-round. A standard above-grade greenhouse fights nature: it''s a thin glass shell trying to hold back winter through brute heating. A Walipini works with nature: it''s a hole in the ground that exploits a free resource billions of years old. Why this matters for Ark thinking: most ''resilience'' technologies fight the world''s tendencies. The Walipini joins them. It''s the rare rig that becomes more efficient as the climate gets harsher — extreme cold barely affects subterranean temperature, while above-ground systems struggle. The rig that proves resilience and elegance can be the same thing. Why every other rig in the Grow domain becomes more powerful when you have a Walipini — the Living Shelf can be installed inside it (no longer needing winter heat), the seedling-starting work that the Window Farm does in winter shifts here for early-spring volume, and the Guild Ring''s most cold-sensitive companion plants overwinter here.
Why this rig is named ''the capstone'' of the Grow domain. The Walipini integrates more domains than any other single rig: Well (Sky Well from glazing, Deep Reserve for irrigation), Power (The Burn for supplemental heat), Loop (The Sanctum for fruit tree fertility), Signal (Sentry monitoring, Actuator vent control), Forge (The Mill for lumber), Shield (The Hedge as windbreak). Building the Walipini before these other rigs are documented means you''re integrating into placeholders. Building it last means every interface is mature. This is also the most expensive rig in the Ark — $6,000 to $25,000 for a canonical 12×20 ft build, comparable to the cost of all the other Grow rigs combined. Be honest about the financial commitment before starting. Why most users will never build a Walipini — and why that''s fine. The Shelf Stack and Living Shelf produce greens year-round indoors. The Porch Garden extends outdoor growing by 4–8 weeks. The Guild Ring produces perennial fruit indefinitely. A household with these four rigs has highly resilient food production without ever digging a pit. The Walipini is for households committed to year-round full-spectrum production — tomatoes in January, citrus in zone 6, the kind of food sovereignty that erases winter from the calendar entirely. Decision framework: build a Walipini if you have land, capital, and a 30-year time horizon. Skip it if any of those three are missing.
The honest practicalities. Permits trip up first-time Walipini builders more than any technical issue. Some jurisdictions exempt agricultural structures; some require engineered drawings; some require setback distances that make a south-facing build impossible on small lots. Get this answered first — a $40 phone call to the building department saves $4,000 in retroactive permit applications. The full build is a 4–8 month project for DIY, 4–8 weeks with contractors. Most failures come from rushing: backfilling against fresh CMU walls before they cure, skipping the French drain because the site ''looks dry,'' using non-XPS foam that absorbs water and fails, installing polycarbonate with the UV side facing inward. The patience isn''t just a virtue — it''s the design. The walls have to cure. The drainage has to be tested before backfilling. The first month of operation is for observation, not optimization. Why this rig demands a different kind of attention than the other Grow rigs. Why building a Walipini changes how you think about food, time, and infrastructure. The shift from ''what should I grow this week?'' to ''what does this structure need to perform reliably for 30 years?'' is the same shift that distinguishes households that survive disruptions from households that don''t.
⑥ Feeds
How this rig connects to the rest of the Ark.
- ← material The Grey Line Filtered greywater → irrigation
- ← material The Sky Well Rainwater → irrigation
- ← material The Deep Reserve Cistern water → thermal mass barrels
- ← material The Mill Lumber → walipini construction, raised beds
- ← material The Apothecary Medicinal plant cultivation requirements (what to grow)
- ← energy The Burn Rocket mass heater → heats greenhouse via piped air or water loop
- ← material The Porch Garden Surplus seedlings (tomato/pepper/eggplant starts that did not fit in the Porch Garden) feed the outdoor rigs — the Porch Garden often functions as the seed-starting nursery for the entire outdoor Grow domain
- ← material The Pump House Backup water source if Sky Well and Deep Reserve are insufficient — particularly during long dry spells or after heavy harvest demand has emptied rainwater storage
- ← information The Sentry The Walipini is the most sensor-rich rig in the Grow domain. Air temp, humidity, soil temp (multiple beds), soil moisture (per bed), CO2 (optional, useful for fruiting crops in winter). Mesh-connected to Ark Core. Climate alerts: above 95°F (vent failure), below 35°F (deep cold event), humidity >90% sustained (mildew risk).
- ← information The Actuator Drives motorized vent openers (electric override of wax-cylinder backups), zoned irrigation valves, and optional shade cloth motors. Most active in summer (heat management) and during deep-cold transitions when wax-cylinder thresholds need overriding by software.
- ← material The Sanctum Finished humanure compost for fruit trees grown inside the Walipini (citrus in zone 6, dwarf figs, persimmons). The Sanctum-to-Walipini Feed extends the Guild Ring's logic into species the outdoor environment can't support.
- ← material The Worm Bank Vermicast top-dressing on raised beds. Smaller volume than the Sanctum Feed but more frequent — monthly or bi-monthly applications keep bed fertility high during peak production
- ← material The Gut Biogas digestate slurry for foliar feeding and root drenches — provides immediate-availability nutrients vs. the slow-release of finished compost; apply diluted (1:10) to avoid nutrient burn
- ← material The Hedge Living windbreak on the prevailing-wind side (typically NW in most US locations). Reduces wind-driven heat loss by 20–40% in winter. Coordinate Hedge planting with Walipini siting — plant the Hedge before or alongside the Walipini build so the windbreak is established by year 1.
- ← material The Window Farm Seedling starts move from indoor windowsills to the Walipini in late winter (when outdoor seedling production is impossible). The Walipini becomes the propagation hub for the entire outdoor Grow domain in early spring.
- ← material The Living Shelf When the Living Shelf is installed inside the Walipini, its aquaponic output (greens, herbs, fish) integrates into the Walipini's broader harvest stream. The fish-water cycle benefits from the Walipini's stable temperatures (50–82°F range) year-round.
- → material The Sky Well Rainwater collected off the angled glazing surface. A 12×20 ft Walipini with 30°+ glazing slope sheds ~150 sq ft of catchment. The Walipini is one of the two largest contributors to Sky Well capacity (along with house roof) — pipes directly to Sky Well rain barrels or cistern via the gutter / downspout system.
- → material The Living Pantry Year-round full-spectrum harvest. Greens always available. Tomatoes Feb–Nov. Peppers May–Oct. Herbs always. Brassicas Sep–April. The Walipini is the only Grow rig that produces every category of fresh produce continuously.
- → material The Worm Bank Plant trimmings, end-of-cycle biomass, fallen leaves. Closed Loop with the Worm Bank — the Walipini's waste stream becomes the Worm Bank's feed stream becomes the Walipini's vermicast stream the next month.
- → material The Gut Larger plant material, end-of-season cleanup — tomato stalks, pepper plants, woody herbs that exceed Worm Bank intake size. Closed Loop with the biodigester.
- → material The Living Shelf When the Living Shelf is installed inside the Walipini, the protected environment removes winter heating requirements; the Walipini's stable temperatures (50–82°F range) suit aquaponics year-round. Combined Walipini + Living Shelf is the most productive single growing space in the entire Ark.
- → material The Guild Ring The Walipini supplies seedlings to the Guild Ring in early spring — fruit tree starts (when grown from seed or grafted in-Walipini), berry shrub propagation, perennial companion plant starts (comfrey divisions, herb starts, ground-cover plugs)
- → material The Porch Garden The Walipini supplies vegetable seedlings (tomato, pepper, eggplant, cucumber starts) to the Porch Garden in early spring when outdoor seedling production is still impossible. Note: the reverse direction also exists — the Porch Garden sends surplus seedlings the other way during peak spring overflow.
- ← material The Grey Line Greywater fed via subsurface drip into Walipini perimeter beds. The Walipini's climate-controlled environment makes it the highest-value greywater destination in the Ark — water demand is steady year-round, and the contained space minimizes evaporation losses. Pair with the Walipini's existing Deep Reserve and Sky Well integrations for a fully diversified water supply.
⑧ Go Deeper
ManyArks endorses no single source — these are starting points that fit the Ark philosophy. In a Vault bundle, these external links require the clearnet.
Concept
What is this and why does it work?
Build
How do I build one?
Building a walipini step by step
French drain installation
Earthbag walls for walipini
Troubleshoot
Mine isn't working
Adapt
How do I modify this for my situation?
grow/walipini
Offline? Same path on any Ark Mirror.