The specification, in the open
The Vaultwood Core Standard
A door is only as honest as the material inside it. Most panels are sold on a name and a finish. Vaultwood Core™ is sold on a number you can check.
Vaultwood Core is a premium medium-density fiberboard (MDF), not high-density fiberboard, held to a published minimum standard[2][11]. Every panel that carries the name has to clear the same bars for density, bending strength, screw holding, moisture, and formaldehyde. Below is the whole standard, in the open. Each line lists the minimum bar, what Vaultwood Core actually delivers, and the test method used to prove it, so you can hold us, or any core, to the same ruler.
Why premium MDF, and why a floor instead of a range
Premium MDF gives a dense, uniform, void-free section that machines cleanly and holds fasteners along the face and edge. That uniformity is what lets a concealed hinge and a locking system stay in tune over thousands of cycles. A range is a marketing number. A floor is a promise: no panel ships under the bar, even when the mill run comes in high.
The minimum-requirements checklist
The bar: linear expansion and thickness swell within ANSI A208.2 limits[2] for the grade, so panels stay flat and true through normal indoor humidity swings. Delivered: a dense, uniform section that stays within those limits across the run[2][11]. Test: ASTM D1037[4].
The bar: 45 pounds per cubic foot, minimum. Delivered: 45 to 49 lb/ft³[11]. This is premium MDF, not HDF; the target is a consistent, void-free core, not the highest possible number. Test: ASTM D1037[4], reported per ANSI A208.2[2].
The bar: 4,000 psi bending strength, minimum. Delivered: 4,500 to 5,500 psi[11]. Test: ASTM D1037[4].
The bar: 250 pounds-force to pull a screw from the panel face, minimum. Delivered: 275 to 350 lbf[11]. Fastener retention is what keeps hinges and hardware anchored over time. Test: ASTM D1037[4].
The bar: within the range set by ANSI A208.2[2] for interior MDF, so panels arrive stable and machine predictably. Delivered: panels conditioned to that interior range before they are cut and cased[2][11]. Test: ASTM D1037[4].
The bar: must comply with EPA TSCA Title VI[7] and California CARB Phase 2[8] emission limits, no exceptions. Delivered: compliance with both[7][8], with no-added-formaldehyde options available on request[11]. Test: emissions verified to TSCA Title VI and CARB Phase 2; panel-product testing per ANSI/HPVA HP-1[6] where applicable.
Supporting properties we also hold to
Modulus of elasticity (MOE): approximately 450,000 to 500,000 psi[11], tested per ASTM D1037[4]. Internal bond (IB): at or above roughly 90 psi[11], tested per ASTM D1037[4].
Proof at the hardware level
Specs on paper matter only if they are measured the same way every time. Every value above is produced by a published test method and is checkable for a given panel[11]. That is what makes the rest possible: uniform density and high screw holding are what let a heavy moving panel carry load and still swing true. Load ratings for a finished door or bed are set and tested by the manufacturer that builds on the core. See the substrate requirements →
How to verify any core in five steps
You do not have to take our word for it. Use this on us, and on anyone else.
- 1. Ask for the spec sheet. Request the density in lb/ft³ and the panel standard it is built to. Premium MDF should read 45 to 49 lb/ft³ and reference ANSI A208.2[2][11]. If a supplier cannot produce a number, that is your answer.
- 2. Confirm density independently. Weigh a known volume, or compare the supplier's reported value against ASTM D1037[4] test data. Below 45 pcf is below the bar.
- 3. Check the strength and holding numbers. Look for MOR, MOE, internal bond, and face screw holding tested to ASTM D1037[4]. MOR at or above 4,000 psi, face screw holding at or above 250 lbf.
- 4. Verify formaldehyde compliance. Confirm the panel is labeled to EPA TSCA Title VI[7] and CARB Phase 2[8]. Ask specifically whether an NAF option is available[11].
- 5. Ask for certifications by name. Request the chain-of-custody and content certifications the panel actually carries, for example SFI, FSC, or CPA Eco-Certified Composite[10]. Named certifications are verifiable; a general claim is not.
Honest ownership and licensing note
Vaultwood Core™ is a trademark and material specification. It is specified, not invented: we specify the core and hold every panel to it, we do not manufacture the fiberboard. Every panel is held to the published minimum standard above, sourcing from qualified suppliers whose spec sheets are on file[11]. The door and hinge systems built on it are separately engineered; the material itself is a known, testable commodity. We are an honest broker of that commodity, and we would rather show you the ruler than ask you to trust the name.
Responsible-claims note: every performance figure on this page is a specification verified by the referenced test method (ASTM D1037[4], ANSI A208.2[2]) or by supplier spec sheets on file[11]. Ranges reflect normal production variation. Numbers are current as of publication and are updated as production data is revised.
The proven use case
See the hidden-door answer
The most demanding use of a premium MDF core is a concealed bookcase door. For the full material argument, see our best material for a hidden door page.