Every part is off-the-shelf. Nothing is custom. Nothing is scarce. The system is not an invention. It is a substitution: we replace the petroleum foam core of a standard SIP with a timber skeleton that Europe already produces in unlimited quantity. The result is lightweight, modular, reversible, and over-engineered to last 100 years. No concrete. No rebar. No curing.
There are no others. Every piece in this list is a standard, certified, mass-produced product available from any builders merchant or logistics depot in Europe. No prototypes. No special orders. No minimum quantities.
| Component | Function | Specification | Source | Unit Cost |
|---|---|---|---|---|
| EPAL Euro Pallet | Ribbed structural core of wall panel | 1200 × 800 × 145mm, ISPM 15, heat-treated softwood | Every logistics depot in EU | €8 - 12 |
| OSB3 Board | Two structural skins bonded to core | 2500 × 1250 × 15mm, EN 300, moisture resistant | Any builders merchant | €12 - 16 |
| Engineered I-Joist | Roof and floor spanning members | STEICO SJ200/SJ240 or equivalent LVL flange | Any timber merchant | €18 - 24/m |
| Helical Ground Screw | Foundation | 68mm diameter, 15-25 kN per screw | Specialist supplier | €30 - 50 installed |
| PU Adhesive + Ring Shank Nails | Bonding the composite panel | EN 204 D4 class, 3.1 × 90mm nails | Any builders merchant | €0.50/m² panel |
This is not a kit. You do not order a Hestia kit from a factory. You walk into any builders merchant, buy these five products, and follow the protocol. The nearest depot to your building site is your supplier. The system scales with knowledge, not with supply chains.
We didn't invent the EPAL pallet. Europe already makes 500 million of them every year, in every country, to a single standard. We didn't change the pallet. We didn't ask anyone to change it. We just noticed that if you put two OSB sheets on either side, the geometry becomes a structural wall panel. The pallet stays exactly what it is. The truck that delivers it keeps driving. Nothing changes in the supply chain, because nothing needs to.
A Structural Insulated Panel uses two OSB skins with a petroleum foam core between them. The OSB carries tension and compression. The foam holds the skins apart. Bonded together, they act as one structural unit.
The problem: the foam core provides almost no shear transfer. Its shear strength is approximately 0.1-0.2 MPa. The panel acts like two independent thin plates. Screw pull-out from foam is approximately 50-100 N per screw, which is useless for hanging cabinets, mounting shelves, or attaching services.
The governing failure mode in a SIP is either OSB skin buckling or adhesive delamination at the foam interface. Neither is easily repaired.
The Hestia Ribbed Composite Panel uses the same principle, two OSB3 skins, 15mm each, bonded to a ribbed core. But the core is not foam. It is an EPAL Euro pallet: a timber skeleton with three stringers, multiple deck boards, and nine blocks, all dimensionally exact to a continental standard.
The timber core provides shear strength of 3-5 MPa, 20 to 50 times that of EPS foam. The stringers act as continuous shear connectors between the skins. Ring-shank nails and structural PU adhesive create a mechanical bond, not just a glued one.
Screw pull-out into the timber stringers is approximately 800-1200 N per screw, 10 to 20 times that of foam. You can mount a kitchen cabinet directly to the wall. You can hang a solar water tank. The wall behaves like solid timber, because it is.
The governing failure mode is OSB nail-head pull-through, the cheapest and most easily upgraded component in the entire system.
| Property | Standard SIP (EPS Core) | Hestia RCP (Timber Core) | Advantage |
|---|---|---|---|
| Core shear strength | 0.1 - 0.2 MPa | 3 - 5 MPa | 20-50x |
| Screw pull-out | 50 - 100 N | 800 - 1200 N | 10-20x |
| Panel weight (1200×800×145) | ~20 kg | ~44 kg | Heavier but far stronger |
| Fire resistance (raw panel) | Melts and drips | Char layer + insulation | Natural fire protection |
| Carbon footprint | Petroleum-based core | Carbon-storing timber | Negative embodied carbon |
| Service attachment | Special inserts required | Direct screw into timber | Simple and strong |
| End-of-life | Landfill (foam not recyclable) | Timber: compost or burn. OSB: recycle. | Circular by design |
| EPAL pallet core (softwood, kiln-dried) | ~25 kg |
| OSB3 skins, 2x 15mm (1200×800 each) | ~17.8 kg |
| PU adhesive + ring-shank nails | ~1.5 kg |
| Total per panel | ~44 kg |
One person can lift and position a panel. Two people can raise a wall panel with a simple wall jack. The weight is comparable to a sheet of 18mm plasterboard (approximately 35 kg/m²), but the structural performance is incomparable.
| 44 RCP panels x 0.053 m³ timber each | 2.33 m³ |
| I-joists (24 x 5m spans) | ~0.60 m³ |
| Roof/floor decking | ~0.40 m³ |
| Total structural wood | ~3.3 m³ |
An equivalent timber frame home uses 8-12 m³ of structural timber. Hestia uses 60-70% less wood. The pallet geometry is inherently efficient: the stringers and blocks create the structure, the voids create the cavities. There is no waste.
The closest project to Hestia in spirit and method is WikiHouse, founded by Alastair Parvin and Nick Ierodiaconou in 2011. They proved that a house could be designed as a digital file, fabricated from sheet material with a CNC machine, and assembled by people without construction training. The parts slot together like a flat-pack piece of furniture. The result is precise, beautiful, and genuinely replicable.
We are not competing with WikiHouse. We are standing beside it. The world needs more than one open-source building system. If you have access to a CNC machine and can afford sheet plywood, WikiHouse is the better choice. If you live in a rural area without a makerspace, without a CNC machine, and without the budget for precision-cut birch ply, Hestia is designed for you. Our panels are built with a nail gun and a circular saw, not a CNC router. Our materials come from a builders merchant, not a sheet goods supplier. Our skill threshold is lower, our tool threshold is lower, and our material availability is higher.
Both projects share the same belief: that housing knowledge should be public, that building should be accessible, and that a family should be able to build their own home without becoming a customer of a financial system that does not serve them. The difference is in the materials and the tools. We are grateful for the path WikiHouse cleared. We are building on it, in a different direction, with a different material set, for a different context.
The generosity of open source. WikiHouse published their designs under a Creative Commons licence. We publish ours under the same licence. The best way to honour a project that gave its work away is to give yours away too. We intend to.
Most pallet architecture projects use pallets "because they are cheap." This is the wrong framing. Pallets are cheap, but that is not why they work. They work because they are the most thoroughly standardised industrial object in Europe.
You are not improvising with scrap wood. You are using a structural element that happens to be the most widely distributed object on the continent. The engineering has already been done, by the pallet manufacturers, by the standardisation bodies, by the logistics industry that relies on these tolerances every day.
The innovation is not the pallet. The innovation is noticing that the pallet is already a ribbed structural panel, and bonding OSB skins to it creates a composite wall system stronger than conventional timber frame, lighter than concrete, and more available than any proprietary system.
This is not "using pallets because they are cheap." This is using an existing industrial language as a construction grammar. That distinction matters enormously. It separates Hestia from every other pallet project that has ever been attempted.
I-joists are used in over 80% of new timber frame construction in Northern Europe. They are a standard product at every timber merchant. You do not order them. You buy them, like you buy timber.
| Depth | Floor Span | Roof Span |
|---|---|---|
| 200mm | 4.5m | 5.5m |
| 240mm | 5.5m | 6.5m |
| 300mm | 6.5m | 8.0m |
| 360mm | 7.5m | 9.0m |
Spans assume domestic floor loading (1.5 kN/m²) and roof loading (0.75 kN/m² snow + dead load). Always consult manufacturer span tables for specific project conditions.
Helical ground screws are the fastest foundation system available. A two-person crew with a handheld hydraulic driver installs 12-16 screws in three to four hours. The sill beam is bolted on immediately. Wall panels go up the same day. No concrete. No rebar. No curing. No weather dependency.
| Aspect | Concrete Slab | Ground Screws |
|---|---|---|
| Excavation | 1-2 days + machinery | None |
| Formwork | 1 day | None |
| Pour | 4 hours + pump truck | N/A |
| Curing | 7-28 days | Immediate |
| Weather dependency | Cannot pour in rain | Any weather |
| Reversibility | Demolition only | Unscrew and reuse |
| Load capacity | 150-200 kN/m² | 15-25 kN per point |
| Time to weathertight | 35-45 days | Same day |
The critical path disappears. In conventional construction, the foundation is the longest critical path item: excavate, form, pour, cure, strip, backfill. With ground screws, the foundation is a half-day non-critical task. The build starts immediately. No concrete truck. No curing anxiety. No weather dependency. The house is over-engineered, but the foundation is elegantly simple.
In a conventional timber frame wall, you drill holes through solid studs. In a Hestia wall, you lay cables in the voids. The pallet structure creates a natural conduit network, vertical chases from the stringers, horizontal chases from the deck boards, that needs no drilling, no weakening of structural members, and no fishing wires through insulation.
| Task | Conventional | Hestia |
|---|---|---|
| First-fix electrical | 2-3 days (drill, fish, seal) | 4-6 hours (lay in voids) |
| Cable capacity per route | 3-4 cables per hole | Unlimited in void |
| Adding a circuit later | Demolition required | Remove face, add cable |
| Outlet placement | Fixed to stud positions | Anywhere on panel |
The 145mm cavity between the OSB skins is filled with blown rock wool by a professional contractor in a single morning. The material is fire-resistant, sound-absorbing, vapour-open, and will outlast the building.
| Wall area (84m² home, 2.5m height, 26m perimeter) | ~65 m² |
| Roof area | ~45 m² |
| Floor perimeter | ~15 m² |
| Total cavity area | ~125 m² |
| Cavity depth | 145 mm |
| Total cavity volume | ~18.1 m³ |
| Rock wool density (blown) | 35 kg/m³ |
| Total rock wool required | ~634 kg |
| Professional installation rate | 8-12 m³/hour |
| Time to fill entire home | 2-2.5 hours |
Compare to batt installation: 2-3 days of cutting, fitting, compressing, and sealing gaps. Compare to spray foam: 1 day application + 24 hours curing + toxic off-gassing period. Blown rock wool is the fastest, safest, and most thermally effective option.
The vapour-open assembly. OSB is vapour-permeable. Rock wool is vapour-permeable. Limewash is vapour-permeable. The entire wall assembly breathes. Moisture moves through the wall, does not get trapped, and does not cause rot. This is the opposite of a foam-sealed airtight envelope, which requires mechanical ventilation and risks condensation at any failure point.
Total tool investment: €300-550. Total material cost for a complete 84m² home: ~€50,000, roughly one-tenth of the European market price. You can take your car to any builders merchant today, buy everything you need, and be weathertight in under two weeks. No concrete. No rebar. No curing. OSB, pallets, I-joists, and ground screws.