Snagging Your London Extension or Conversion: What to Check Before Signing Off

**What is a 'snag'?**

• A snag is a defect, an unfinished item, or an item that does not meet the specified or agreed standard. Snags are different from variations (changes to scope agreed during the project) — they are failures to complete or comply with what was already agreed. Common examples:
• •A painted surface that has drips, runs, or missed patches
• •A door that does not close fully or binds in the frame
• •Tile grout that is uneven, cracked, or insufficiently filled
• •An electrical socket that is not flush to the wall
• •A window that does not open and close smoothly
• •A skirting board with a visible gap at the corner joints
• •Plaster that is not smooth and has hollows or ridges
• •A floor that squeaks or flexes underfoot
• •External pointing that is crumbling or poorly finished
• •An extract fan that has not been commissioned or does not run

Most snags are minor — they are the typical imperfections that occur in any construction project and are expected to be remediated by the contractor before final handover.

**When to do the snagging inspection**:

The snagging inspection should take place when the contractor declares the works substantially complete — but BEFORE the final payment is made. 'Substantial completion' means that the works are sufficiently complete for the homeowner to occupy and use the space, with only minor items remaining. It does not mean the works are perfect.

• The timing matters:
• •*Too early*: Snagging when there is still significant work to complete produces a list that will be superseded — there is no point snagging plastering when the painter has not yet finished
• •*Too late*: Making the final payment before snagging removes the homeowner's financial leverage — the contractor has been paid in full and has no commercial incentive to return for snags

The ideal sequence: 1. Contractor declares substantial completion 2. Homeowner walks the project and prepares a snagging list 3. Snagging list agreed (in principle) with the contractor 4. Contractor remediates snags (typically within 2–4 weeks) 5. Homeowner re-inspects and confirms snags addressed 6. Final payment released

**What to bring to a snagging inspection**:

• *Equipment*:
• •A torch (for inspecting dark corners, inside cupboards, under kick-boards)
• •A spirit level (for checking level of worktops, tiles, shelves)
• •A straight edge (1m or 2m aluminium straight edge for checking flat plaster surfaces)
• •A smartphone with camera (for photographing every snag)
• •A notepad or a snagging app (Snagr, PlanGrid, or a simple numbered list in Notes)

• *Documents to have to hand*:
• •The agreed specification (the scope of works or contract schedule): what was agreed in terms of materials, finishes, and quality standard
• •Any drawings or plans referenced in the contract
• •Manufacturer specifications for any products installed (tiles, worktops, kitchen, bathroom fittings) — to compare against what is actually installed

**Room-by-room snagging checklist for a London rear extension**:

• *Structural and external*:
• •External brickwork: joints raked out and pointed consistently; no cracks; no mortar droppings; expansion joints where specified
• •External render (if applicable): no cracks, crazing, or hollow sections (tap with knuckles for hollow sound indicating delamination); finish texture consistent
• •Flat roof: falls adequate (no ponding visible); upstand height adequate (minimum 150mm); membrane lapped and sealed at all penetrations; drainage outlets clear and unobstructed
• •Rooflights: glass undamaged; frame seals intact; opens and closes smoothly
• •Rainwater goods: gutters aligned and fall correct toward downpipes; downpipe connected to drain (not discharging onto patio)
• •Cavity wall: weep holes present in outer leaf (every 3–4 courses above cavity tray level)

• *Internal — general*:
• •Plaster: run the straight edge across all plaster surfaces; any deviation of more than 3mm in 1.5m should be queried; plaster should be clean, smooth, and free from cracks (hairline shrinkage cracks are expected in fresh plaster but should be pointed out)
• •Painting and decorating: all surfaces painted to agreed finish (matt, eggshell, or gloss as specified); no drips, runs, or missed patches; two coats minimum on new plaster
• •Floors: timber floor level and flat (no excessive springiness); tiles level and grout joints consistent and fully filled; screed flat (max ±3mm in 2m for a standard screed)
• •Skirting boards: all mitres and butt joints tight; no gaps at floor level; painted consistently with walls
• •Architraves and door casings: mitred corners tight; consistent reveal gap around all doors
• •Ceiling: flat and painted; plasterboard joints not visible (especially critical in rooms with raking light)

• *Joinery and fittings*:
• •Doors: all doors open and close without binding; latches engage fully; door stops fitted; fire doors close fully from any open position; hinges and ironmongery all tight
• •Windows: open, close, and lock smoothly; trickle ventilators present and operable
• •Kitchen: all units level and aligned; doors all in plane; worktop edges and joints sealed with silicone; kick-boards all fitted; appliances connected and operational
• •Bathroom: all sanitaryware secured; silicone sealed at bath/shower tray perimeters (no gaps); shower enclosure doors open and close smoothly; WC flush mechanism operational; extract fan operational

• *Electrics and plumbing*:
• •All sockets and switches flush to wall and cover plates tight
• •Light fittings all present, working, and fully fitted
• •Extract fan runs (and runs on timer/humidity sensor if specified)
• •All taps: hot and cold water running from all taps; no drips or leaks at supply or waste connections
• •Heating: if UFH, confirm manifold commissioning and zone operation; radiators if fitted — heat up correctly and bleed valves accessible
• •Smoke alarms: all interconnected alarms operational (test with test button); CO alarm present if gas appliance installed

**How to record snags effectively**:

A snagging list needs to be specific, numbered, and referenced to a location — not vague. Compare:

*Vague (not useful)*: 'Plastering needs attention'

*Specific (useful)*: 'Kitchen — north wall (window wall) — plaster finish rough and inconsistent in 600mm × 400mm area to right of window frame at approximately 1.5m height. See photo #12.'

• *Template for each snag entry*:
• •Snag number (sequentially numbered)
• •Location (room, wall, surface — be precise)
• •Description (what the defect is, including dimensions where relevant)
• •Photo reference (photo filename or number)
• •Agreed action (once agreed with contractor — e.g., 'make good plaster and repaint' or 'adjust door frame'
• •Completion date (when the contractor agrees to complete)
• •Status (open / in progress / complete — updated after re-inspection)

**Sharing the snagging list with the contractor**:

• Send the snagging list to the contractor in writing (email is fine — it creates a record). The covering message should:
• •Reference the contract and the project
• •State that the snagging list is provided following the inspection of [date]
• •Request confirmation of the contractor's programme for addressing each snag
• •State that the final payment will be released once the snagging list is confirmed as complete to the homeowner's satisfaction

**Professional snagging surveyors**:

For significant projects (whole-house refurbishments, complex extensions, high-value loft conversions), some homeowners engage a professional snagging surveyor — typically an independent building surveyor (RICS-chartered) or an architect — to carry out the snagging inspection on their behalf.

• *Advantages*:
• •Professional surveyors know what to look for and will identify technical snags that a homeowner might miss (inadequate plaster tolerance, non-compliant installation of fire doors, ventilation not commissioned)
• •Their written snagging report carries more weight than a homeowner's list when the contractor disputes items
• •RICS-chartered surveyors can provide formal certification that the works are or are not complete and compliant

*Cost*: £300–£800 for a professional snagging inspection and report for a typical London extension; higher for more complex projects.

**Retention — the financial mechanism for ensuring snagging is completed**:

• In many standard building contracts (JCT Minor Works, JCT Homeowner/Occupier), a retention is held from interim payments — typically 3–5% of the contract value. The retention is released in two stages:
• •*50% of retention at practical completion*: Released when the certificate of practical completion is issued
• •*50% of retention at the end of the defects liability period (DLP)*: Released 6–12 months after practical completion, after the contractor has attended to any defects notified during the DLP

• For a £100,000 extension contract with 5% retention:
• •£5,000 retention is held during the works
• •£2,500 is released at practical completion
• •£2,500 is held for 6–12 months (the defects liability period) and released after defects are addressed

Many smaller residential contractors resist retention — if a contractor insists on full payment at practical completion, ensure the snagging list is agreed and the contract includes a defects liability clause (even without financial retention, the contractor has a contractual obligation to return and rectify defects during the DLP).

**The Defects Liability Period (DLP)**:

The defects liability period (also called the rectification period in some contracts) is a contractual period — typically 6–12 months after practical completion — during which the contractor is obliged to return and make good any defects that appear in the completed works. The DLP is not a warranty period — it does not cover defects caused by the homeowner's misuse or fair wear and tear; it covers defects arising from the contractor's workmanship or materials that become apparent after the works are handed over.

• *What the DLP covers*:
• •A crack that appears in new plasterwork 3 months after completion (possibly due to shrinkage that was not properly managed at the time of plastering)
• •A flat roof membrane that begins to delaminate at a detail within 6 months of completion (indicating an inadequate adhesion at installation)
• •A door that begins to stick in winter (indicating the door was hung with insufficient clearance for seasonal timber movement)
• •A trickle ventilator that does not operate (installed but not commissioned)

• *What the DLP does not cover*:
• •A crack caused by the homeowner hanging a very heavy picture with an inadequate fixing
• •Condensation caused by the homeowner's very high moisture generation without adequate ventilation
• •Wear and tear on floor finishes

*During the DLP*: keep a log of defects as they appear; notify the contractor in writing (email) as they occur; give the contractor a reasonable time to attend and remediate; do not withhold payment for items notified during the DLP (the snagging process at practical completion is the moment for leverage — the DLP process is the follow-up).

**What to do if the contractor refuses to return for snags or defects**:

*Step 1 — Written notice*: Send a formal written notice (ideally by recorded letter and email) identifying the snags or defects and giving a specific deadline for remediation (typically 14–28 days).

*Step 2 — Mediation*: If the contractor does not respond, suggest mediation through a recognised service — FMB offers a mediation service for disputes involving FMB members; RICS conciliation and mediation is available for larger disputes; the Construction Industry Disputes Resolution Service (CIDR) offers mediation. Mediation is significantly cheaper and faster than litigation.

*Step 3 — Adjudication or arbitration*: If mediation fails, the contract may contain an adjudication clause (required for contracts above a certain value under the Housing Grants, Construction and Regeneration Act 1996 — though this applies to commercial contracts above £0 where the project is a 'construction contract'). Adjudication is fast (decision typically within 28 days) and enforceable.

*Step 4 — Legal action*: Small claims court (up to £10,000 in England) for minor snagging costs; county court for larger claims. Get legal advice from a solicitor specialising in construction disputes before starting legal action — costs can exceed the disputed amount if not managed carefully.

*Step 5 — If the contractor has left the industry or gone insolvent*: Check whether a structural warranty is in place (may cover major defects directly); check if the contractor was registered with a trade association that has a compensation scheme (FMB has a deposit protection scheme for members); seek legal advice on options for recovery from an insolvent contractor.