Quick answer: You have 2 years from legal completion to report defects to your developer under the NHBC, Premier Guarantee or LABC structural warranty. After that, you’re on your own. Windows and doors account for around 30% of all new-build snagging items reported in the first year — and many of them are easy to miss until winter arrives. This guide gives you the full checklist room-by-room, how to test each item, what counts as a snag vs normal wear, and how to push back when the developer says “that’s normal”.
Print this off, walk around with a torch, and tick off every item. Most snags take 5 minutes to spot and 30 minutes for the developer to fix.
Why snag windows and doors specifically?
New-build construction is a fast process. Windows and doors are usually fitted before the rest of the house is finished, then knocked around by trades for weeks. Common consequences:
- Frames left out of square because the wall around them moved as it dried
- Gaskets damaged by careless trades passing tools through openings
- Sealant gaps around the frame because the plasterer worked around them
- Trickle vents not fitted (now a Building Regs issue — see our trickle vents guide)
- Glass panes scratched by the sticker residue of the safety sticker
- Locks not aligned because the door was hung with packers that loosened
None of these are major faults — but if you don’t catch them in the first 2 years, you’ll be paying to fix them yourself. Snagging is your one shot at zero-cost remedies.
Your statutory protection (NHBC / Premier / LABC)
Most UK new builds come with a 10-year structural warranty. The first 2 years are the “defects insurance period” where the developer is responsible for correcting any defects in workmanship or materials — including windows and doors. Years 3–10 only cover major structural items.
- NHBC Buildmark — covers ~80% of UK new builds
- Premier Guarantee — second-largest provider
- LABC Warranty — used by some local authorities and developers
- Checkmate, BLP Insurance — smaller providers, similar terms
All work the same way: report defects in writing during the 2-year window and the developer is obliged to fix them. After 2 years, only major structural items are covered. Don’t wait until month 23 — give yourself buffer time.
The window snagging checklist (room by room)
Visual inspection (every window)
- ☐ Frame square in the opening — use a spirit level on all 4 sides
- ☐ Even gap between frame and wall (typically 8–12mm) all the way round
- ☐ Sealant bead continuous, no missed sections, especially at corners
- ☐ No cracked, chipped or scratched glass (look from inside AND outside, in low sun)
- ☐ No sticker residue on the glass (the safety markers leave glue if not removed within 30 days)
- ☐ Gaskets intact, no damaged or loose sections
- ☐ All glazing beads present (the strips holding the glass into the frame)
- ☐ Drainage holes at the bottom of the frame open and not blocked
- ☐ Trickle vents fitted to all habitable-room windows (see trickle vents guide)
- ☐ External weatherboards / cills don’t slope back toward the wall (water will sit and rot)
Functional tests (every opening window)
- ☐ Opens smoothly without lifting or forcing
- ☐ Closes flush — no daylight visible around the sash when shut
- ☐ Locks engage cleanly without forcing the handle
- ☐ Friction stays adjusted — sash doesn’t drop when opened part-way
- ☐ Restrictor stays (child safety on upper-floor windows) work as intended
- ☐ Trickle vent slider opens and closes
- ☐ No rattling or movement when closed and locked
Performance tests (more time-consuming, do once per house)
- ☐ Draught test — close window, hold a lit match or thin tissue near the seal on a windy day. No movement = sealing properly. See our draughty windows guide.
- ☐ Spray test — gently spray the outside of the window with a hose. No water inside? Good. Water visible inside or wet patch on the wall = serious snag.
- ☐ Thermal test — first cold morning, run the back of your hand around the frame edges. Cold spots could indicate poor insulation or a missing thermal break.
- ☐ Sound test — close all windows, listen. If a sash isn’t sealing, you’ll hear outside noise more clearly than other rooms.
The door snagging checklist
Front door + back door
- ☐ Door square in the frame — gap consistent on all 4 sides (3–5mm typical)
- ☐ Closes flush against the seal all the way round
- ☐ Multipoint lock engages all points smoothly without forcing
- ☐ Letterbox rebound spring works (front door)
- ☐ Threshold seal in place and not damaged
- ☐ Door swings without scraping the floor or frame
- ☐ Glass panel (if fitted) intact, no cracks
- ☐ External handle and lock are smooth, not stiff
- ☐ Spy hole / number plate fitted as agreed
- ☐ External cill drains away from the door (water shouldn’t pool against it)
French / patio doors
- ☐ Both leaves close and lock smoothly
- ☐ Active and passive leaves seal against each other (run a tissue test)
- ☐ Bolts on the passive leaf engage cleanly
- ☐ No movement when the active leaf is locked and gently shaken
- ☐ Drainage holes at the bottom of the frame open
- ☐ Threshold doesn’t allow water in from outside
Bi-fold / sliding doors
- ☐ Track clean and free of debris
- ☐ Doors slide / fold without dragging
- ☐ Locks engage without lifting the door
- ☐ Rollers / wheels move smoothly (you may need to adjust on first use)
- ☐ No daylight visible at the joints when fully closed
- ☐ Threshold weather seal intact
Snag vs lived-in wear — what’s worth pushing on
| Issue | Snag (push for fix) | Normal wear (live with) |
|---|---|---|
| Visible scratch on glass | Yes — within 12 months | No after the 2-year window |
| Stiff handle | Yes if it’s stiff from day one | If it develops at year 4+ |
| Tiny daylight gap at corner | Yes — sealing fault | — |
| Surface scuff on frame | Yes if obvious + within 6 months | Smaller marks at year 2+ |
| Door rubs in extreme heat | Yes if it doesn’t open at all | Slight expansion is normal |
| Trickle vent missing in habitable room | Yes — Building Regs breach | — |
| Misted glass | Yes — sealed unit failure (covered by warranty) | — |
| Condensation on inside glass in winter | Often a ventilation issue, not a window snag | See our condensation guide |
Common developer pushback (and how to respond)
- “That’s within tolerance.” Ask which standard. Most quote NHBC tolerances; cross-check against the actual NHBC Standards (publicly downloadable). Window frame plumbness tolerance is typically ±3mm over 1m — anything beyond that is a snag.
- “That’s a wear-and-tear item.” If the issue was visible at handover or appeared within the first 12 months, it’s a defect, not wear. Insist on the 2-year defects period coverage.
- “You’ll need to use it for it to settle in.” Sometimes true for door rubs in fresh frames. Give it 30 days. If it persists, raise it again.
- “That’s the homeowner’s responsibility.” Ask for the written reason. Get it in writing on the developer’s letterhead. Most pushback evaporates when written.
- “We’ve sent the snagging team and they say it’s fine.” Get the inspection report in writing. Compare to the photos you took. Escalate to the warranty provider (NHBC, Premier, LABC) if you disagree.
How to formally report
- Document everything with photos. Date-stamped. Include the room, the snag, and a wide shot for context.
- Compile a single snag list rather than reporting items one at a time. Developers respond better to one organised email than 30 separate texts.
- Email the developer’s customer care team. Reference your plot number, contract date, and the warranty provider.
- Set a reasonable response window — most warranties define this (e.g. 21 days for response, 60 days for repair).
- If unresolved after that window: escalate to the warranty provider directly (NHBC dispute resolution, Premier Guarantee complaints, etc.). All have free dispute mechanisms.
- Last resort: small claims court for amounts under £10,000.
Should I hire a professional snagger?
Professional snagging surveyors charge £300–£600 for a 3-bed semi inspection. Whether it’s worth it depends on:
- Worth it if: Large house (4+ bed), high-spec build, you’re not confident inspecting yourself, or the developer has a poor snagging reputation.
- Skip it if: Small property, you have construction knowledge, or you’re using this checklist methodically.
Pro snaggers typically find 50–150 items on a typical new-build inspection. Most are minor. The ones worth hiring for are the structural and waterproofing items hard to spot without training — chimney flashing, roof felt overlap, brickwork mortar joints. Window/door snags from this checklist you can do yourself.
Frequently asked questions
When should I do my snagging inspection?
Three rounds: Day 1 (handover walk-through with developer), Month 6 (after lived-in faults emerge), and Month 22 (just before the defects period closes). Don’t leave it all to one inspection — different snags surface at different times.
What if the developer has gone bust?
Your structural warranty (NHBC, Premier, LABC) takes over. Report the same defects to them via the warranty’s dispute mechanism. They’ll arrange repairs from approved contractors at no cost to you.
Can I withhold the final payment?
Generally no — you’ve completed the purchase. But you can refuse to sign the customer satisfaction certificate that the developer wants for their records. This sometimes accelerates response time.
My windows have condensation on the inside — is that a snag?
Usually not. Internal condensation is a humidity / ventilation issue, often caused by drying-out of new construction (concrete and plaster releasing moisture for 6+ months). See our condensation guide. Snag it only if it’s between the panes (sealed unit failure) or persists beyond 6 months with proper ventilation.
What if I miss the 2-year window?
You’re then on Consumer Rights Act 2015 territory — you can still pursue the developer for defects that were present at handover but were latent (not visible). Harder to prove. The 2-year window is the easy route; don’t miss it.
If you need replacement windows or doors
If the developer refuses to fix a serious snag and you’ve exhausted the warranty route, our quote service connects you with up to 4 vetted FENSA-registered local installers in 24 hours for replacement. Free, no obligation.
Related: Trickle Vents Building Regs · U-Values & WER · IBGs Decoded
Sources: NHBC Buildmark warranty handbook, Premier Guarantee policy documentation, LABC Warranty consumer guide, HomeOwners Alliance snagging list (2026), New Home Quality Code, Consumer Rights Act 2015, Approved Document F (2022 trickle vents update), HBF customer satisfaction survey 2025–26. Last reviewed: April 2026.
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