Month nineteen. A stain on the ensuite ceiling of 8.03, the apartment below 9.03. The building handed over in February of last year, the defects liability period closed in February of this one, and the owner of 8.03 has a photo of a brown ring and a reasonable question: whose is this?
The builder's first answer is the one builders give, and it is not unreasonable: the DLP ended five months ago and this was not on any list. The owner's answer, also reasonable: nobody could have put it on a list, because it is inside the floor above. Both of them are right, which is what makes a latent defect a latent defect, and why the argument that follows is never about the stain.
Nobody could have seen it. Somebody still has to prove when it started.
That is the opinion. A latent defect is the one case where "you should have found it at handover" is not the answer, and that cuts both ways. The owner cannot be blamed for not lifting the tiles in 9.03 on the pre-completion walk. The builder cannot be blamed on the strength of a stain that appeared nineteen months after anyone last looked at that ceiling. So the argument moves off the stain and onto dates.
When was the membrane in 9.03 laid, and by which trade? Was it inspected before it was tiled over, by whom, against what? Is there a certificate? When did the stain first appear, and when was the builder told? Those are five facts. Every one of them either exists on a record made at the time by somebody who did not know it would matter, or it does not exist at all, and no amount of expertise in month nineteen creates it.
Patent and latent, in four items
The chipped tile in the entry is patent. Visible from the doorway on the pre-completion walk. Listed or it is the inspector's fault.
The membrane under that tile is latent. Laid in month four, tiled over in month five, invisible at handover. The only inspection that would have found a fault in it is the one that happened, or did not happen, before the tiles went down.
The door that does not latch is patent. Anybody who tries the door finds it.
The missing fire collar above the plasterboard ceiling in the riser is latent. Found three years on when the fire engineer opens a panel for an unrelated reason. The defect existed from the day the ceiling closed. The knowledge of it did not.
The law in most places treats the two kinds differently, and the detail of how is a question for your state and your contract, which is why the only thing we have published about the periods is a table with a source on every row. The general shape is this: the contractual DLP is short and closes; the statutory periods are longer and differ by state; and for a latent defect the clock is argued from when the defect was, or could reasonably have been, discovered. Which means the record of when it was discovered is as important as the record of when it was built.
The evidence was made by people who were not thinking about evidence
Here is the part that matters for anyone still building. The record that decides a latent-defect claim in month nineteen is almost entirely made during the build, by people answering a checklist.
D1 on the pre-completion list: waterproofing certificate sighted for this wet area. Yes, by a named inspector, on a date. The hold point on the waterproofing before tiling, if the job ran an ITP: released by the builder's QA, with a photo of the membrane up the wall and into the niche, before the first tile. The pre-pour check on the slab, with the cover meter log. The photo of the riser before the ceiling closed, taken because the checklist asked for one, with the time the phone recorded when it was taken.
None of it was taken for a claim. It was taken because the question was on the list. Nineteen months later it is the only account anyone has of what was inside the floor of 9.03, and whether it was there is the difference between a conversation and a case.
This is why "the inspection raised it" matters more than it sounds. A checklist that produces a tidy PDF of ticks has recorded that somebody ticked. A checklist where each answer carries a name, a time and a photo, and where a No raised a defect that was then fixed and verified, has recorded what was actually in the wall. In IssuesId that is what an inspection is: every answer has who and when on it, a hold point stays open until released, and the photo keeps the original device timestamp the camera wrote into it.
When the stain appears
The other half of the record is made in month nineteen, and it is simpler, provided the register is still running.
The owner of 8.03 scans the card they were given at handover and raises the stain against 8.03's ensuite, with the photo and today's date. The building manager types it Warranty, because it is water coming through a floor, not a tap dripping, and issues it to the builder by email, with a link. The email is on the trail with whether it was delivered. If the builder disputes it, which they might, they dispute it on the record and the adjudication stays on the file.
Now there are two records on the same register, nineteen months apart: the one from the build, saying what was inspected in 9.03 and when, and the one from the stain, saying when it appeared and when the builder was told. The history reads them in order. Who did what, when, with what evidence. The argument does not vanish. But it is now an argument about two documents rather than two memories, and that is the most anyone can do about a defect nobody could have seen.
The definition, with the four examples, is at what is a latent defect. The periods by state are on one page. General information, not legal advice; the contract and your state's law decide how a latent defect is treated.