Last updated: 2026-10-27. This checklist is what we walk through with every client at handover — the same 12 points, in the same order. Prices and documents referenced here match our current published specification.
Quick answer: the 12 checks, in order
Inspection works best in sequence: documents first, then structure, then services, then sign-off. Do not start with the aesthetics — paint and trim are the easiest things to fix and the least important.
| # | Check | Pass criteria | Typical failure |
|---|---|---|---|
| 1 | Document pack | Mill cert, insulation cert, fire rating, warranty, as-built drawings | Missing or undated certificates |
| 2 | Arrival condition | No twist-lock damage, no dents on frame, no water inside | Water ingress through vents |
| 3 | Level and alignment | Structure level within 5 mm, no gaps at base | Uneven footings |
| 4 | Welds and galvanising | Continuous welds at corners; touch-up where coating is burned | Untreated weld burn |
| 5 | Panel joints and sealing | Sealed gaskets, no daylight through joints | Gaps at corner posts |
| 6 | Water test | 10-minute hose test, no ingress at corners or openings | Leaks at window sill |
| 7 | Doors and windows | Smooth operation, locks align, no draught | Frame twisted during transport |
| 8 | Electrical | RCD trips, earth continuity, correct breaker rating | No earth bond to steel frame |
| 9 | Plumbing | 30-minute pressure test at 1.5× working pressure | Weeping at joints |
| 10 | Insulation and condensation | Continuous vapour barrier, no thermal bridge at frame | Compressed insulation at corners |
| 11 | Fire safety | A-class insulation evidence, extinguisher point, clear escape route | Wrong insulation substituted |
| 12 | Snag list and sign-off | Every item dated, owner assigned, warranty start date agreed | Open items closed verbally |
When to inspect: after the units are set on footings and connected, before the final payment milestone. Not on arrival day alone — half of all defects only appear once the building is closed up and pressurised.
1. Demand the document pack before anything else
Ask for these five documents before you walk the site. If any is missing, the inspection has not started.
- Steel mill certificate — grade, thickness and zinc coating of the coil used for the frame and panels (we use Q235 with 30 g/m² zinc coating, certified to GB/T 2518-2019)
- Insulation certificate — density and fire rating of the sandwich panel core
- Fire rating evidence — an A-class test or material declaration, not a marketing claim
- Warranty document — what is covered, for how long, and from which date
- As-built drawings — layout, structural openings, and service entry points as actually built, not as originally quoted
Our own document set — ISO 9001/45001/14001, the rock wool CE attestation to EN 13162, the A-class rock wool certificate, and the steel mill certificate — is published on the about page, so you can compare what you receive against what we claim.
2. Check the units on arrival, before unloading
Inspect while the units are still on the truck or trailer. Once they are on the ground and levelled, transport damage becomes your problem to prove.
- Twist locks and corner castings: no deformation, no cracks
- Frame edges: dents deeper than 5 mm indicate a forklift or crane impact
- Interior: no standing water, no condensation on panels
- Packaging: corner protection intact, no torn wrap on the glazed faces
Photograph everything before lifting. If the damage is transport-related, the claim sits with the carrier, and photos taken after unloading rarely win that claim.
3. Verify level and alignment
A container house is only as square as its footings. Check with a spirit level at four points per unit and a laser if you have one.
- Level tolerance: 5 mm across a 20ft unit, 8 mm across a 40ft unit
- No gaps between the base frame and the footing pads
- Anchor bolts or straps fitted as per the drawing, not “to follow”
Uneven footings are the most common cause of door misalignment reported three months after handover. Fixing it later means re-levelling the building.
4. Inspect welds and galvanising
Walk the perimeter with the unit closed. You are looking for two things: weld continuity and coating repair.
- Corner welds: continuous, no pinholes, no spatter left on the surface
- Weld burn: any area where galvanising has burned off must be wire-brushed and coated with zinc-rich paint
- Rust spots: none on delivery; isolated spots mean the coating was damaged in transit
A unit with untreated weld burn will show rust within one rainy season. This is a five-minute check that prevents a five-year problem.
5. Panel joints, gaskets and sealing
Run your hand along the internal joints and look for daylight.
- Gasket compression: even along the full length, no gaps at corners
- Sealant: continuous bead, tooled, no cracks or voids
- Corner posts: the highest-risk leak point — check both inside and outside
- Floor-to-wall junction: sealed, especially on units with a shower or kitchen
6. Run a proper water test
A visual check on a dry day proves nothing. Take a hose.
- Spray each elevation for 2–3 minutes, starting low and working up
- Concentrate on window sills, door thresholds, corner posts and roof-wall junctions
- Have someone inside with a torch, checking joints and the floor edge
- Total test time: at least 10 minutes per unit
Document any ingress with a photo and a location description (“north-west corner, 400 mm above floor”) — vague snag items get argued about later.
7. Operate every door and window
Open, close and lock every opening at least twice.
- Sliding doors: no binding, latch engages without force
- Windows: stay open at any position, no draught when closed
- Locks: key turns smoothly, handles return to rest
- Screens and blinds: fitted, operating, not fouled by the frame
If a door binds, the frame has twisted — re-check level at that corner before adjusting the door itself.
8. Electrical safety: five tests that matter
This is where cheap builds cut corners, and where a certificate is not the same as an installation.
| Test | Method | Pass |
|---|---|---|
| RCD trip | Press the test button on each residual current device | Trips within 300 ms |
| Earth continuity | Meter between socket earth and steel frame | Below 1 ohm |
| Insulation resistance | Megger between live and earth | Above 1 MΩ |
| Breaker rating | Compare to the incoming supply and cable size | Matches schedule |
| Socket polarity | Tester on every outlet | Correct L-N-E |
Also confirm: the distribution board is labelled, spare ways are blanked, and the main earth bond to the steel structure is visible and accessible.
9. Pressure-test the plumbing
Run the test before the units are connected to the site supply.
- Fill the system, bleed air, pressurise to 1.5× working pressure
- Hold for 30 minutes; a pressure drop of more than 0.5 bar means a leak
- Check every visible joint with a tissue — weeping shows as a damp patch
- Test hot and cold separately if the unit has a water heater
- Confirm drain falls: water should clear without pooling
10. Insulation and condensation
You cannot see insulation once the panels are closed, so verify it two ways: on the certificate, and at the cold bridges.
- Certificate: density and fire class stated, batch number matching the delivery
- Thermal bridging: feel the frame at the corners and around openings on a cold day — a cold, damp strip means the vapour barrier is broken
- Vapour barrier: continuous behind the internal lining, sealed at every penetration
- Ventilation: trickle vents or mechanical extract working, especially in bathrooms and kitchens
Condensation complaints in the first winter almost always trace back to a broken vapour barrier at a corner, not to the insulation itself.
11. Fire safety at handover
- Confirm the insulation actually installed matches the certified A-class product — ask for the batch number on the delivery note
- Extinguisher: one per 200 m², mounted, charged, signed
- Escape route: clear, and every sleeping room has an openable window
- Smoke alarms: fitted and tested in living and sleeping areas
- Service penetrations: fire-stopped where cables and pipes pass through panels
12. Write the snag list and agree the warranty start
The inspection is not finished until the paperwork is.
| Column | What to record |
|---|---|
| Item number | Sequential, matched to a photo |
| Location | Unit number + description (“Unit 3, NE corner post”) |
| Defect | Factual, not interpretive (“gap 4 mm at joint”) |
| Severity | A = safety/watertight, B = function, C = cosmetic |
| Owner | Supplier or installer, by name |
| Target date | Agreed, in writing |
| Status | Open / closed / accepted as-is |
Two clauses worth having in the contract before you start: the warranty clock starts at handover sign-off (not at shipment), and retention is released only when all A and B items are closed.
The first 30 days: what to watch
Even a clean handover can reveal issues once the building is in use. Check these at day 7, 14 and 30.
- Day 7: any new water marks at corners, doors starting to bind, condensation on frames in the morning
- Day 14: RCD test again (nuisance tripping often appears after the first week of load)
- Day 30: settlement check — re-level, re-check door alignment, inspect sealant for cracking
Log what you find. A supplier who responds well in the first 30 days is the one worth keeping for the next order.
FAQ
Who should attend the delivery inspection?
The supplier’s QC representative, the installation crew leader, and a client representative with authority to sign. If you are importing, hire a local third-party inspector for the handover — a half-day inspection typically costs less than one snag visit.
How long does a handover inspection take?
Two to three hours for a single 20ft unit, half a day for a multi-unit camp. The water test alone needs 10 minutes per unit, and the plumbing pressure test another 30 — plan for the time rather than rushing it.
Can I inspect before final payment?
Yes, and you should. Structure the contract so the final milestone is released after a signed handover report with all A and B items closed. Suppliers who resist this condition are telling you something.
What if the insulation does not match the certificate?
Reject the batch. Fire rating and thermal performance are declared properties; a substitution is a misdescription, not a minor deviation. Ask for the delivery note batch number and the certificate batch number side by side.
Do I need a third-party inspector for a container house?
For a single unit, a competent site engineer with this checklist is usually enough. For camps of 20 units or more, or where the project is financed, a third-party inspection is standard and pays for itself in closed snag items.
What documents should be handed over at sign-off?
Warranty certificate with the start date, as-built drawings, electrical test results, plumbing pressure test record, material certificates (steel, insulation, fire rating), and the operating manuals for any fitted equipment.
Related guides
- Container house quality inspection: factory audit and QC — the pre-shipment side of the same process
- Container house installation: complete guide — footing, lifting and connection
- Container house shipping and freight — what happens between the factory and your site
- Container house cost guide — what should be included in the quoted price
- Technical datasheet pack — specifications you can send to your engineer
