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Pre-existing condition of a home photographed before the renovation starts

Renovation dispute

How to prove the pre-existing condition before the work starts

When the client says you made that crack, your word is worth the same as theirs. A photo sealed on day one, before you touched anything, is not.

Seal the pre-existing condition

Private. Only the file fingerprint is registered.

Word against word “That crack wasn’t there.” “This isn’t what we agreed.” With nothing dated, the argument is won by whoever is holding the payment.
The dated proof wins Photos of the pre-existing condition sealed before you start, and the quote sealed before it is signed. No longer your word: a date.
Cents against thousands A renovation dispute is thousands of euros and weeks of wear. Sealing every job costs cents. Today, nothing.

The scene

“You made that crack.”

Final visit. The renovation is finished and all that is left is the last payment. The client takes you into the hallway and shows you a thin crack running down the partition wall to the skirting board. “That wasn’t there. You did it with the machines.” You know it was there. You saw it on day one, when the furniture was still in. You thought about taking a photo, and someone called you. Now it is your word against theirs. “Until you fix it, I’m not paying the rest.” And the worst part is you know how it ends: fixing the crack for free to close the job.

The ritual: day one on site, before you touch anything

  • Before signing: seal the quote and its attachments exactly as you send them, as a PDF. If the scope changes, seal each new version. That way “this isn’t what we agreed” is answered with the exact version and its date.
  • Day one on site, before you unload a single tool: walk through the home and photograph the pre-existing condition. One wide shot per room and one close-up of every crack, damp patch, flaking paint, scratched floor or dubious installation.
  • Photograph what you are about to cover up too: pipework, drains, walls that will end up behind a partition. Tomorrow nobody will be able to see them.
  • Before you start work: put the photos in a ZIP and seal it from your phone. Two minutes. The date on the seal has to be earlier than the first intervention.
  • Keep the ZIP and the certificate in the job folder, with the quote and the contract. Repeat the ritual on every job: it is the same gesture as filling in a job sheet.

Just need to fix the date of a few photos of the prior condition? How to certify a photo with a date and time →

What Sellat proves in this dispute

Sellat does not decide who caused the damage, whether the work was done properly or what the quote should have included. That is for an agreement, an expert or a judge. Sellat proves one concrete thing: that those photos of the pre-existing condition and that exact quote existed on the date you sealed them, and that nobody has modified them since. It is technical evidence about an exact version of a file. With it, “that crack was already there” stops being just your word.

What you keep after sealing

When you seal, you receive the PDF certificate and your proof package by email. That package is what you put on the table when the claim arrives: inside it is the exact file that was sealed, its fingerprint, the date and the instructions for the client, their expert or their lawyer to check it without trusting you or Sellat. In the normal flow Sellat does not keep your photos or your quote after the proof is created, so keep that package yourself in the job folder — or turn on custody, optional and free with an account.

Registered post proves what you sent and when. Sellat proves which photos you had, and when.

Damage verification on a building job has one problem: by the time you need it, the damage is already covered, repaired or under dispute. Phone photos don’t solve it, because the date is set by your phone and it can be changed. Sealing does for your photos what registered post does for your letters: it fixes a date that does not depend on you. It works for the professional who covers themselves on every job, and for the client who documents their home once, before the crew comes in.

Inside the package

This is exactly what you open two years later.

Not a promise and not a screenshot: the real list of files Sellat puts in your ZIP. What you see here is generated by the same module that builds the package.

Open the package Close the package
  • original/<archivo> If the original is kept

    Your file, byte for byte

    The exact photo you sealed, in a folder of its own so no other file in the package can be mistaken for it. It travels inside when the original is available: the upload that created the proof, or custody.

  • certificado-<id>.pdf Always

    The readable certificate

    The PDF you show a person or attach to a filing. It is an informative document: what actually gets checked is the file, not the PDF. If the file carried Content Credentials (C2PA), the certificate records them too — who signed, with which tool and whether they declare AI use — exactly as your browser read them when you protected it.

  • proof.json Once the batch is anchored

    The portable proof

    Your file fingerprint, its Merkle leaf and inclusion path, the batch root and the public transaction that records it. This is the piece that lets anyone check everything without Sellat.

  • sello-cualificado-<id>.tsr With a qualified seal

    The qualified seal

    The RFC 3161 response from the qualified timestamping authority, exactly as it was issued. This is the file that fixes the date under eIDAS.

  • autoridad-sellado.pem With a qualified seal

    Who signed the seal

    That authority signing certificate, with its SHA-256 written into the README. It travels inside so the check works offline and nobody has to go looking for it.

  • anclaje-bitcoin.ots Once the batch is anchored

    The Bitcoin anchor

    The OpenTimestamps proof of the batch root. It may still be waiting for a block: it is a valid file and whoever receives it can upgrade it themselves.

  • LEEME.txt / README.txt Always

    The instructions, in two languages

    What each file is, what it proves and what it does not, and the exact commands to check it. In Spanish and English, so an expert or a lawyer never has to ask you anything.

The seal is signed by FNMT-RCM, not by Sellat.

Sellat is not the party attesting the time. The qualified seal is issued by a qualified timestamping authority of the FNMT-RCM, and its signing certificate travels inside your package. We are the intermediary that joins your fingerprint to that seal and hands it to you in a tidy folder.

It checks out without us and without the internet.

With the seal and the authority certificate inside the ZIP, the date is verified with standard tools on the machine of whoever receives it. If Sellat disappeared tomorrow, your package would still check out.

The package proves that this exact file existed on that date and has not been modified. It does not prove who created it, who took the photo, or what happened in front of the camera.

Seal the pre-existing condition before you touch anything.

A renovation dispute is thousands of euros. Sealing the day-one photos and the quote costs cents; today, nothing. Two minutes from your phone, on every job.

Seal the pre-existing condition

Frequently asked questions

Before you ask.

Does it work if the client doesn’t sign anything?

Yes. You seal your files on your own: the client doesn’t have to sign, agree or even know you have done it. If the dispute comes, anyone can verify the proof with the ZIP you received. A pre-existing condition report signed by both of you and sealed the same day is better still, but it is not a requirement.

How many photos do I take, and of what?

One wide shot of each room from the door and one close-up of everything that could later be put on you: cracks, damp, flaking paint, floors, joinery, exposed installations and everything you are about to cover up. Daylight, no filters. Seal them all together in one ZIP: one proof per job, not a hundred.

Does the PDF of the quote count?

Yes. Seal the exact PDF you send to the client, with its attachments. If the scope changes later, seal the new version: each one keeps its own date. When they tell you “this isn’t what we agreed”, you will have the exact version you sent, and when.

Will this hold up in court, or with an expert?

Sellat does not promise that a proof will hold up in court, and it cannot: the judge or arbitrator in each case is the one who weighs the evidence. What you can bring is technical evidence, verifiable by anyone, that those photos and that quote existed on that date and have not been modified since. On the legal page we explain precisely what Sellat proves and what it does not.

What if I have already started the work?

Seal today what is still untouched and what you have already done. You won’t fix the condition on day one, but you do fix today’s: if damage later shows up that is not in these photos, you have a dated reference to argue from. It does not prove on its own who caused it, but it stops being word against word. And on the next job, the ritual starts before you unload the van.

Can anyone see my file?

It depends on the mode. In the normal flow the file is uploaded to Sellat only to calculate its SHA-256 fingerprint and prepare the proof; afterwards it is not retained. With a free account, Sellat Local calculates the fingerprint on your own device and the original is never uploaded. And if you turn on custody — optional, and only with an account — Sellat does keep the original, checked against its fingerprint, until you remove it. In all three cases the only thing in the public record is the hash, a code that cannot be used to read or rebuild the content.

Damage verification on building work: pre-existing condition, who pays and quote disputes

On a renovation, the dispute almost always turns on two questions: what condition the home was in before the work started, and what exactly the quote included. Photos taken before the renovation and the PDF of the quote answer both, as long as their date doesn’t depend on anyone’s word. With that, “damage during works: who pays” stops being an argument in the dark. Technical detail, in case you need it: Sellat computes the SHA-256 fingerprint of the exact file (the ZIP with the pre-existing condition photos, or the PDF of the quote), records it in a public reference on Polygon and on Bitcoin via OpenTimestamps, and sends you a PDF certificate and a verification ZIP. In the normal flow the original file is not kept after the proof is created: only its fingerprint. With an account you can calculate it on your device (Sellat Local) or turn on custody so Sellat keeps the original too. Anyone can check the proof with the exact file, without an account and without trusting Sellat. For studios and companies that seal every job as a matter of course, there is an API.