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Defects Guide
A category-by-category guide to the defects most often recorded during our pre-handover and pre-completion snagging inspections — drawn from real SHI reports and cross-referenced to the NHBC Standards 2026 and the Scottish Building Standards Technical Handbook (Domestic, April 2026).
From a real sample inspection — 4-bed detached, central Scotland
Across the property and grounds, our inspector recorded 50 items — 1 Category 1, 36 Category 2 and 13 Category 3, of which 15 were flagged safety-critical.
The substantial majority were finishing and adjustment matters of the kind normally expected on a new build at handover. The Category 3 and safety-critical items — covering alarms and fire separation, guarding, glazing in critical locations, the boiler flue clearance, the unvented cylinder discharge arrangement, and missing main protective bonding — should be addressed before legal completion.
§ Structure & fabric
The first category we work through on every inspection — the external envelope of the home. Defects in this category are the ones most likely to be safety-critical or weatherproofing-sensitive, so they're often the ones flagged for resolution before completion.
Map-pattern cracking in the through-coloured render, providing a route for water to reach the substrate. Cut out and make good in accordance with the system manufacturer's repair detail, and confirm the cause is not background movement.
A concrete interlocking tile has slipped from its course, breaking the weathering line and exposing the underlay and batten beneath. Re-seat and mechanically fix, and inspect adjacent tiles for nib or fixing failure.
A gutter union joint is weeping, with staining tracking down the render below the joint. The seal has not seated correctly. Remove, clean and re-seat the union with a new gasket, and clean down the staining.
Mortar pointing inconsistent — a mix of struck and recessed profiles with several unfilled perpend joints. Rake out and re-point to a consistent profile to match the approved sample panel.
§ Internal finishes
The largest single category by volume on a typical inspection. Most are Category 2 — the builder is expected to resolve them under warranty during the initial defect period.
A continuous shrinkage crack runs along the wall-to-ceiling junction, typical of early-life drying movement but presented unfinished at handover. Rake out, fill with a flexible decorator's filler and redecorate.
Several nail/screw pops and pronounced roller stipple are visible under raking light from the window. Re-fix popped fixings, fill, sand and re-coat to an even finish.
The plastered wall bows visibly when checked with a 2m straightedge, exceeding the permitted deviation. Re-skim or float the affected area to bring the surface within the SD10 flatness tolerance.
Brown damp staining with spots of black mould forming at the external wall junction, indicating a condensation or cold-bridge issue. Establish and remedy the moisture source (ventilation/insulation), treat the mould, then make good.
A consistent gap is open between the top of the MDF skirting and the wall, left uncaulked at handover. Caulk the skirting-to-wall gap and redecorate to a clean line.
§ Joinery & doors
Adjustment-level defects that often appear because trades work in sequence — carpets fitted after doors are hung, hinges not re-adjusted afterwards.
The door binds against the frame on the latch side and does not sit square in the opening, catching before it latches. Ease and re-hang the door, adjusting hinges so it operates freely and latches cleanly.
The mitre joint at the head of the door architrave has opened, leaving a visible wedge-shaped gap. Re-fix and fill the mitre, then redecorate.
Wardrobe doors out of alignment with an inconsistent shadow gap and one door standing proud at the base. Adjust the hinges and hanging to bring the doors level with a consistent shadow gap.
A deep scratch across the lower rail and a run in the factory paint finish. Fill, rub down and re-finish, or replace the leaf if the damage cannot be made good.
§ Kitchen & wet areas
Defects in this category often progress quickly under daily use, so they're a priority to put right early. Several can rise to Category 3 (urgent) where there is a water-ingress risk.
The laminate worktop mason's mitre at the return is open and proud, with the joint not pulled tight — a water-ingress risk to the chipboard core. Re-make the joint with fresh sealant and correctly tensioned bolts, flush and watertight.
Excessive lippage between adjacent tiles on the shower wall, with edges standing proud enough to catch a fingernail. Lift and re-lay the affected tiles to a flat plane within the lippage tolerance.
Grout is cracking and inconsistent in colour and depth, with several joints under-filled. Rake out and re-grout the affected joints to a consistent colour and depth.
The silicone seal between the bath and the tiled wall is discoloured with mould growth and has pulled away in places, breaking the waterproof line. Strip out and renew with a sanitary-grade silicone after drying the joint.
Elevated moisture and staining at the base of the shower enclosure tiling indicate water is tracking behind the tiles, suggesting a tanking or seal failure. Expose and rectify the waterproofing/tanking behind the shower, then reinstate the tiling.
Water ponds on the floor tiling rather than draining, with no effective fall toward the gully — standing water remains after use. Re-lay the floor screed/tiling to achieve a positive fall to the drainage point.
§ Windows & glazing
Window defects span both adjustment-level Category 2 items and the more serious Category 3 issues where the weathering line or safety glazing is compromised.
The handle turns but the espagnolette does not throw fully, leaving the sash unsecured. Adjust the keeps and gearing so all locking points engage with the handle fully home.
The drip groove to the underside of the cill has been bridged with paint, so water can track back to the wall face rather than dripping clear. Rake out the paint to reinstate a clear, continuous drip groove.
The full-height fixed side panel adjacent to the patio door — a critical location — carries no visible safety-glazing kitemark, so compliant toughened/laminated glass cannot be confirmed. Confirm the pane is safety glass to BS EN 12600; if marking or evidence is absent, replace with marked safety glazing.
External perimeter sealant missing along the head, leaving an open gap between frame and reveal. Apply a continuous low-modulus weatherproof sealant bead to the frame perimeter.
The composite door multipoint lock requires the door to be lifted hard on the handle before the bolts will throw, indicating the keeps are out of adjustment. Adjust the hinges and lock keeps so the mechanism engages smoothly without lifting.
§ Heating & services
Items that are typically commissioning snags — radiators not level, valves not freed off, taps not adjusted — together with the safety-critical items around boiler flueing and unvented hot-water discharge.
The flue terminal externally is closer than the permitted distance to an opening window, risking re-entry of combustion products. Relocate the flue terminal or the opening to achieve the manufacturer's and Building Standards clearances.
The temperature/pressure relief discharge pipe terminates at high level above the rear path, where hot water discharge could scald a person below. Re-route the discharge to terminate safely low-level over a gully with a guard, per G3 / Building Standards.
The radiator is fitted noticeably out of level, sloping down toward the valve end. Re-fix the radiator brackets to bring the unit level.
The TRV is seized and will not turn, so the room temperature cannot be controlled. Free or replace the TRV head and confirm the pin operates.
The mixer tap drips steadily from the spout when closed, indicating a worn or unseated cartridge. Replace the tap cartridge/washer to stop the drip.
The sink waste trap in the base unit is weeping at the compression joint, with water marking the cabinet base below. Re-make the waste trap connections and confirm watertight under flow.
§ External works
Often inspected last and frequently incomplete at handover. Block-paving sand washout and gully fall issues are the most common items in this category.
Joint sand not topped up, with localised dishing and settlement leaving low spots in the wearing course. Top up jointing sand to specification and re-level any low areas.
Weatherproof sealant bead is discontinuous around the penetration, leaving an open route for water ingress behind the render. Strip and reseal with a continuous low-modulus weatherproof sealant.
Independent. Civil-engineer led. Standards-referenced findings against NHBC 2026 and Scottish Building Standards. Detailed photo report within 24-48 hours.
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