Snagging is the process of identifying defects and incomplete items in a building project before you sign off on completion and release the final payment. It's not optional and it's not pedantic. Every project has snags: the question is whether you identify them before or after the builder has been paid in full and has moved on to the next job.
Once the final payment is made and practical completion is certified, your leverage over the contractor drops significantly. Before completion, you have the final payment. After completion, you have the contract's defects liability period (typically 12 months, sometimes less), but enforcing defect rectification through correspondence, and possibly legal action, is a very different proposition from doing a snagging inspection and saying "fix these before I pay."
When to Do the Snagging Inspection
The snagging inspection happens at practical completion, which is the point at which the building is substantially complete and fit for occupation, even if minor finishing items remain. This is not the same as final completion (when every last item is done to perfection).
Time the inspection carefully. Don't agree to a practical completion date when you haven't actually seen the finished work. Agree that the contractor will notify you when they believe the work is ready for inspection, inspect it, and only certify practical completion once you've reviewed the snag list and are comfortable with what remains to be done.
Inspect in good daylight. Artificial lighting hides surface defects that are obvious in daylight. Go through every room systematically, not in a rush. Take a notepad and camera. A torch is useful for checking inside cupboards and roof spaces.
If your project is significant (a full house extension or larger), consider commissioning an independent snagging survey from a qualified surveyor or clerk of works. They know what to look for, they have no relationship with the contractor, and their report carries professional weight that your own notes may not.
External Items
Brickwork and masonry. Check pointing is consistent and complete. No mortar smearing on face brickwork. Soldier courses and specials are level. DPC is at correct height above finished ground level (150mm minimum). Weep holes in cavity wall DPC courses are clear.
Roof. Check from ground level and, if safely accessible, from inside the roof void. Ridge tiles are bedded or mechanically fixed. No slipped or cracked slates/tiles visible. Lead flashings to chimney, abutments, and valley positions are well dressed and not lifting. Gutters are securely fixed, fall to downpipes is correct (minimum 1:350 fall), and joints are sealed. Downpipes are vertical and clipped to the wall at appropriate intervals.
Windows and external doors. All opening lights operate smoothly and lock correctly. Threshold strips are present and secure. Mastic sealing to window reveals is complete and neat. No cracks in the masonry around window and door openings.
Drainage. All drain covers are present, correct type, and at finished ground level. No cracked covers. Downpipe connections to gully or drain are properly made and not displaced.
External ground works. Paving and path falls away from the building. No surface water ponding adjacent to the building. Landscaping and reinstatement complete as specified.
Internal Structure and Finishes
Walls and ceilings. No cracks in plasterwork (hairline shrinkage cracks at window corners are normal and not a defect; wider cracks or those running across plastered surfaces are worth noting). Painted surfaces are even, no missed areas, no brush marks or roller marks visible at an oblique angle in good light. Colour is consistent across surfaces.
Floors. Timber floors are level (no bounce suggesting unsupported sections) and without squeaks at this stage. Tile floors are flat (no lippage between tiles), grout is complete, and silicone at junctions is finished neatly. Carpet is secure at edges and thresholds. LVT or laminate is fully clicked together with no lifting at joints.
Joinery. Doors open and close smoothly without binding or catching. Door handles, hinges, and latches operate correctly. Fire doors close fully on the latch without being forced. Skirting boards and architraves are mitred neatly at corners, pinned securely, and caulked at the top. Kitchen unit doors and drawers align correctly and have consistent reveal gaps.
Staircase. No loose balusters. Handrail is secure and the correct height (900mm-1000mm above pitch line). Newel posts are fixed. Treads and risers are secure with no movement or squeaking.
Services
Heating. Turn on the boiler and run the heating. Check each radiator warms up (or each underfloor heating zone responds). Bleed radiators if air is present. Check the boiler manual and commissioning certificate are left on site. Hot water reaches all outlets within a reasonable time.
Electrical. Test all sockets with a phone charger or similar. Switch every light switch and confirm lights work. Check pendant positions and ceiling roses are centred in the room or positioned as specified. Smoke and CO detectors are present in required locations and test buttons respond. Consumer unit is accessible, labelled, and the Electrical Installation Certificate is provided by the electrician.
Plumbing. Run taps and showers and confirm adequate flow and temperature. Check under sink and bath for leaks after running for several minutes. Flush toilets and confirm cisterns refill correctly. Check washing machine and dishwasher connections if applicable.
Ventilation. Test all extractor fans. Confirm kitchen extraction actually exhausts externally (some inferior installations recirculate). Check MVHR filters are clean and access panels are installed.
Documenting and Following Up
Write up the snag list systematically. Describe each defect specifically (not "walls look bad" but "bedroom 2 south wall: paint streak at approximately 1.5m height, approximately 600mm long, adjacent to the window reveal"). Photograph every defect with something for scale.
Send the snag list to the contractor in writing (email is fine and creates a timestamped record). Agree a timescale for rectification: two to four weeks is reasonable for most snag items, longer for anything requiring materials to be ordered or specialist work.
Once snags are rectified, re-inspect each item before confirming it's closed. Don't assume. A quick visual re-inspection of the specific items is much faster than the original survey and is worth doing before releasing the final payment.
Keep a small retention amount. If your contract allows for a retention (typically 3-5% of the contract value withheld for 12 months after practical completion), use it. It provides an incentive for the contractor to return and address any defects that emerge during the first year. If your contract doesn't include a retention clause, it's harder to negotiate retrospectively, which is why it should be in the original contract.