There’s a pallet of blocks on your drive, a stack of flooring in the garage and a kitchen in boxes in the spare room. Who owns them? The question sounds academic until a builder fails, a supplier’s van arrives to “collect our goods”, or you’re asked to pay a stage that’s mostly materials, at which point the answer is worth thousands. The law here is old, clear and worth ten minutes.

Rule one: incorporation ends every argument

Once materials are built into the structure, blocks laid, boards fixed, boiler plumbed in, they cease to be goods and become part of the land. Ownership passes to the landowner (you), automatically and irreversibly, whether or not anyone was ever paid for them. A supplier’s unpaid invoice for bricks that are now your wall is a debt claim against the builder, never a right to the bricks. Nobody can lawfully strip fixed materials out over a debt, and threats to do so are just that, see handling threats in a dispute.

Rule two: until then, title follows the paper

Unfixed materials are ordinary goods, and ownership sits where contracts put it:

  • Supplier → builder: virtually every merchant sells on retention of title terms (the “Romalpa clause”): goods remain the supplier’s until paid for. Builder hasn’t paid the merchant? Those loose materials on your site may genuinely still belong to the merchant, even if you paid the builder for them (the builder can’t pass title it never had).
  • Builder → you: your contract governs. JCT forms address it directly: materials on site become the employer’s on payment for them, and the contractor may not remove them; sensible bespoke contracts say the same.

The collision of those two bullets is the classic homeowner loss: stage payment made, materials stacked on site, builder folds owing the merchant, and the merchant’s retention of title beats your payment to the insolvent builder.

Protecting yourself at the payment moment

For material-heavy stages, the staged-payments discipline gains three refinements:

  1. Pay against supplier invoices, ideally direct. “£6,800 for the windows” is safest paid to the window company (with the builder’s agreement), or against the builder’s evidenced, paid supplier invoice, which extinguishes the retention of title.
  2. Identify the goods. Materials “for your job” should be deliverable-to and stored-at your site, marked or documented as yours (photos of the delivery notes in your site diary). Goods sitting unallocated in a builder’s yard are the insolvency practitioner’s, in practice.
  3. Vesting language for big-ticket items. For off-site manufactured items paid in advance, the staircase, the glazing units, a short vesting certificate (supplier confirms the identified goods are yours, stored for you) is standard industry practice and takes a supplier ten minutes to sign. Refusal tells you the deposit is really funding cash flow.

And the ever-green fundamentals: Section 75 on card-paid sums reaches vanished-materials losses too, and money kept behind the work caps every version of this problem.

The reverse cases

Builder’s own plant and surplus stock remain the builder’s, a parting of ways means securing them for collection, not keeping them. Demolition arisings and salvage (the old fireplace, the roof slates, the copper) are yours unless the contract says otherwise, agree their fate in the scope before strip-out, because “the lads weighed in the copper” is a genuinely common Friday surprise, and reclaimed materials have real value.

This guide is general information for homeowners in England and Wales, not legal advice.