Snagging isn't only for new builds. When your builder says the extension is finished, you go round it together, list everything that isn't right, and agree when it will be fixed. Doing it properly protects the money you still owe and the paperwork you'll need when you sell.
Practical Completion: What It Means
Practical completion is the point at which the work is finished apart from minor defects and the extension can be used. Depending on your contract, it usually triggers the final payment (less any retention) and the start of the defects period, during which the builder must come back and fix problems that appear.
The Snagging Walk-round
- Do it in daylight, with the builder, and write the list as you go.
- Photograph every snag and agree a date for each fix.
- Email the list afterwards, so it's dated and in writing.
What to Check
- Where old meets new: cracks at the junction with the existing house, inside and out, and how the new roof meets the old wall (flashings and lead work).
- Floors: a level, step-free transition into the extension if that was designed, and no bounce.
- Openings: bifold and sliding doors that run smoothly, lock and seal, with no cracking around beams or lintels.
- Weathering: roof coverings finished, gutters and downpipes connected, and no sign of water getting in.
- Drainage: gullies and manholes accessible, and rainwater going where the drawings show.
- Finishes: the same checks as a new home. Our snagging checklist works room by room.
Paperwork Before the Final Payment
- Building control completion certificate. This shows the work was signed off under the Building Regulations. Without it you'll have problems when you sell.
- Electrical installation certificate for new circuits, with the work notified under Part P.
- Window and door certificates (such as FENSA or CERTASS) where they were fitted by a registered installer.
- Gas Safe certificate if any gas work was done.
- Guarantees for the roof, windows and any insurance-backed warranty the builder offered.
Retention: Keep Some Money Back
Many building contracts let you hold back a small percentage of the price, called a retention, until the end of the defects period. It gives the builder a reason to come back. Agree the amount and the length of the defects period in writing before work starts; it's much harder to agree afterwards.
If Something Looks Structural
Diagonal cracks, doors that start sticking months later, sagging over openings or cracks that get wider deserve an engineer's view, not just the builder's reassurance. Good Building Regulations drawings and structural calculations prevent most of these problems in the first place. Worried about yours? Send us photos.