Snagging After Completion: Defects That Show Up Later
What to do when problems appear weeks or months after the builder has left: how to tell a defect from wear, when to check, and how to report it under the warranty.
The short version
Some problems only show up after the builder has gone. Spotted early and reported clearly, most are put right without fuss.
The snagging walk-round at the end of a job catches what is visible on the day. Other things only appear later: a damp patch after the first heavy storm, a crack as new plaster dries out, a rooflight that lets in a draught once the weather turns cold. That is not a failure of the snagging process. New work settles, and some faults only reveal themselves under real conditions.
What matters is noticing them early, telling the contractor clearly and giving them a fair chance to come back. A workmanship warranty is designed for exactly this, and paying the final balance does not mean you have given up on having defects put right.
This guide covers what to look out for in the months after completion, how to tell a defect from ordinary wear, how to report a problem so it gets dealt with, and what to do if the contractor does not respond. For the walk-round at handover itself, see final payment and snagging.
Knowing what you are looking at
Snag, defect, or something else
At handover, a snag is a small unfinished or imperfect item: a missing trim, a paint mark, a gap to seal. What is a snagging list? covers those. After completion, the word tends to be used more loosely for anything that turns up. It helps to be a little more precise, because it affects who is responsible and how quickly it needs dealing with.
A defect is a fault in the work itself: something not fixed properly, a joint that leaks, a finish that fails well before it should. Defects in the contractor's workmanship are what a workmanship warranty exists to cover.
Settling and drying out can produce hairline cracks in new plaster, small gaps where timber has shrunk, or a door that sticks for a season. Some of this is normal, particularly on extensions. Whether it counts as a defect depends on how far it goes and what the contractor told you to expect.
Everything else includes wear and tear, storm or accidental damage, a fault in a product rather than in how it was fitted, and changes you or another trade made afterwards. These generally fall outside a workmanship warranty, although a product fault may be covered by the manufacturer's own warranty.
Warranty cover
What a workmanship warranty usually covers, and what it usually doesn't
The exact terms are in your contractor's warranty, so read it. These are the general patterns.
Usually covered
- Faults caused by how the work was done
- Leaks traced to the new work
- Fixings, joints or seals that fail early
- Finishes that fail because of poor preparation
- Movement or cracking beyond what is normal for new work
Usually not covered
- Ordinary wear and tear over time
- Storm damage or accidental damage
- Faults in a product rather than its fitting
- Work altered by you or another trade
- Parts of the building that were not worked on
When to look
Six good moments to check the work
A few deliberate checks in the first year catch problems while they are still small.
After the first heavy rain
Look inside below the new work: ceilings, walls, the loft and around any rooflight. Check the gutters and downpipes are carrying water away.
A few weeks after completion
A calm look round once you have lived with the work. Small items missed at handover often show up now.
When the heating goes on
New plaster and timber dry out and move as the house warms up. Look for cracks, gaps, and doors or hatches that start to stick.
After strong winds
Check from the ground for anything out of place on the roof or around flashings. Don't go up yourself.
Before and after other trades
If someone else works near the new work, note its condition before and after. It keeps responsibility clear.
Before the warranty ends
A careful check a month or two before the warranty period runs out, so anything outstanding is reported in time.
Reporting it
How to report a defect so it gets dealt with
Deal with anything urgent first
If water is coming in, take sensible steps to limit the damage: move belongings, catch the water and, if needed, arrange a temporary repair. Keep a record of what you did and why.
Photograph it, with dates
Close-ups and wider shots that show where it is. Video helps with leaks. Note when you first noticed it and what the weather was doing.
Check the warranty terms
Who to report to, how, and whether there is a time limit for reporting after you notice a problem. If the warranty sets out a process, follow it.
Report it in writing
Describe what you have seen, where and since when, attach the photographs, and ask when the contractor can inspect. Keep a copy. Keeping evidence and records explains what to hold on to.
Give a fair chance to put it right
Agree a date for a visit and be reasonably flexible about access. A contractor who cannot get in cannot fix it.
Record the outcome
When it is fixed, photograph the repair and confirm in writing that it is done. If it comes back, you have a clear history.
A written warranty sits alongside your rights under the law rather than replacing them. Under the Consumer Rights Act 2015, a service must be carried out with reasonable care and skill, and those rights do not necessarily end when a warranty period does, although there are legal time limits for bringing a claim. If you arrange a temporary repair to stop damage getting worse, keep it to what is reasonable, keep records, and tell the contractor promptly. Citizens Advice publishes guidance. This is general information, not legal advice.
Keeping it constructive
Getting a contractor back without friction
Contractors generally want to put right their own work. It protects their reputation, and it is usually cheaper for them than a dispute. A clear, calm report with photographs gives them what they need to plan a visit. A string of angry calls does not.
Report problems as you notice them rather than saving them up. A single item reported promptly is easy to deal with. Six items reported the week before the warranty ends can feel like an ambush, even if they are all genuine.
Be open to the contractor's explanation. What looks like a leak can be condensation, and what looks like a failed joint can be movement elsewhere in the building. If they say it is not their work, ask them to explain why in writing. If you remain unconvinced, an independent view from a surveyor can settle it. Our guide to dealing with defective workmanship covers disputed defects in more depth.
Avoid bringing in another contractor to fix it before the original one has had a fair chance, other than for an urgent temporary repair. Doing so can complicate any later claim for the cost. Getting remedial work done explains when bringing someone else in makes sense.
If a report goes unanswered
Moving things forward when the contractor doesn't come back
If your report goes unanswered, follow up in writing after a few days, referring to your first message and its date. If there is still no response, send a clear written complaint that sets a reasonable deadline. Raising a complaint with a builder covers how to word it.
If the contractor disputes the defect or will not return, the next options are an independent report, mediation or another form of ADR, and as a last step a court claim. If the business has stopped trading, a warranty from that business generally goes with it, unless it was backed by an insurance-backed warranty or a similar arrangement, so check your paperwork. The when building work goes wrong guide sets out each route.
Looking after new work
An aftercare file and a little maintenance
Keep everything about the job in one place: the accepted quote, any written changes, invoices and receipts, the warranty, any product documents and certificates, and the photographs you took during and after the work. Add a simple log of anything you notice afterwards, with dates. If a problem appears in year two, that file is what gets it dealt with quickly.
Read the warranty for anything it asks of you. Some warranties expect reasonable maintenance, such as keeping gutters clear or not altering the work without the contractor's agreement, and some ask for problems to be reported within a certain time of being noticed. Knowing this early avoids an argument later about whether cover still applies.
Ordinary upkeep also protects the work. Clearing leaves from gutters and valleys, keeping rooflight seals clean and ventilating rooms while new plaster dries all help new work settle well. None of this shifts responsibility for a genuine defect onto you. It simply keeps the picture clear if something does go wrong.
If you use Mortaro
Report it to us and we chase it
Mortaro coordinates domestic building projects. Your appointed main contractor, named in your quotation, carried out the work and provides the workmanship warranty: a minimum of 12 months across our network, usually from completion, and often longer on larger works, with the exact terms confirmed in your quotation.
If something shows up after completion, tell us by phone or email, with photographs if you can. We raise it with your contractor on your behalf, push for a visit and a resolution, and keep following up so you are not left chasing. Contractors who fail to put their work right are removed from our network.
We don't inspect the work, and the warranty is your contractor's rather than ours, so we don't pay for repairs ourselves. Our part is making sure the report is heard and acted on. Putting things right explains the process.
Straight answers
Questions about defects after completion
Can I report a problem after I have paid the final balance?
Yes. Paying the balance does not end the contractor's responsibility for defects in their work. Report it in writing under the warranty, with photographs.
How long does a workmanship warranty last?
It depends on the contractor and the job, and the terms should be in your paperwork. Workmanship warranties explained covers what to look for.
Are hairline cracks in new plaster a defect?
Often not. Fine cracks as new plaster dries are common and are usually dealt with when you redecorate. Wider or growing cracks, or cracks alongside other signs such as sticking doors, are worth reporting.
Should I fix a leak myself?
Take reasonable steps to stop damage getting worse and, if needed, arrange a temporary repair. Leave the permanent repair to the contractor unless they have had a fair chance and failed to act, and keep records of everything you do.
Is damage from a storm covered by the workmanship warranty?
Usually not, unless the damage happened because the work was not done properly. Storm damage is normally a matter for your home insurance. If you are unsure which it is, report it to the contractor and your insurer and let the facts decide.
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