What is a Pre-Commissioning Punch List and How is it Used?
Before any building system can move from pre-commissioning into live commissioning, every outstanding defect, incomplete installation, and missing document must be recorded, assigned, and cleared. That record is the pre-commissioning punch list.
Unlike a general contractor’s snagging list, a pre-commissioning punch list is a formal contract document generated during systematic walk-downs of each piece of equipment and building system. Under ASHRAE Guideline 0, it functions as a structured quality gate – items are categorised by criticality, assigned to responsible parties, and tracked to verified closure before the commissioning team can proceed. Understanding what pre-commissioning involves is the foundation; the punch list is the instrument that enforces it. This article covers what the punch list contains, how Priority A, B, and C items work, who manages it, and what a clean closeout actually looks like.
What a Pre-Commissioning Punch List Actually Is
A pre-commissioning punch list is a formal, project-level document that records every item found during pre-commissioning walk-downs that is incomplete, defective, or non-compliant with design intent. Each item is categorised by priority [Priority A, B, or C], assigned to a responsible contractor, vendor or trade, given a target completion date, and tracked until it is independently verified and closed.
In the context of building commissioning, it carries real project consequence: systems do not advance to the next phase until the relevant punch list items are closed out.
The punch list is generated system by system, discipline by discipline, during the pre-commissioning walk-down phase. Items flow onto it in real time as the team inspects against design drawings and specifications. The word “punch” comes from an old paper-based practice: contractors would physically punch a hole next to each item once completed, as a tamper-proof record.
You will also hear this document called a snag list [UK, Ireland, Australia, New Zealand], an issues log, observation register, a deficiency list, a commissioning issues register, or a defects register, depending on where you are in the world and what the contract says. The terminology varies; but the document is the same.
How the Punch List Fits Into the Pre-Commissioning Process
The punch list is generated during the walk-down phase of pre-commissioning – the systematic, system-by-system inspection that happens after construction is substantially complete but before formal commissioning begins. Walk-downs are typically conducted with three parties present: the contractor responsible for the system, the commissioning team, and an owner representative. Every item that does not meet installation / design intent is entered on the punch list at the time it is discovered, with a priority, description, location, and assigned party.
Within the ASHRAE Guideline 0 commissioning process, the punch list sits in Stage 3 [the Construction Phase], after mechanical completion has been declared or is approaching. The sequence looks like this:
| Step | Activity | Notes |
| 1 | Construction reaches mechanical completion or approaches it | The trigger point for pre-commissioning activities to begin |
| 2 | Pre-commissioning walk-downs begin, system by system | Conducted jointly by the commissioning team, responsible contractor, and owner representative |
| 3 | The pre-functional checklist [PFC] is worked through system by system during the walk-down | The PFC is the structured questionnaire; the punch list is the live register of everything that fails or is missing. They work together but are not the same document |
| 4 | Items that fail or are incomplete are raised directly onto the punch list | Entries are made in real time during the walk-down, with priority, description, location, and assigned party recorded |
| 5 | The punch list closes [in the correct category order] before the system achieves Ready for Commissioning [RFC] status | All Category A and B items must be independently verified and closed before RFC is declared |
The punch list is a live document from the moment walk-downs begin. In practice it will run for weeks or months — new items added as additional walk-downs occur, closures happening in parallel. The key rule: no system achieves RFC [Ready for Commissioning] status until all Priority A and Priority B items are independently verified and closed.
That RFC gate is what makes the punch list the key document in the transition from construction to commissioning. Get it right and handover flows. Leave items unresolved and the programme stalls.
Punch List Item Categories: A, B, and C Explained
Pre-commissioning punch list items are classified into three priorities based on when they must be resolved. Priority A items are safety-critical or prevent mechanical completion from being declared. Priority B items must be cleared before commissioning [functional testing] begins — the RFC [Ready for Commissioning] gate. Priority C items must be resolved before the commissioning completion certificate is issued.
No system advances to the next phase until all items in the required categories are verified and closed.
This three-tier structure is what gives the punch list its gatekeeping function. Without it, you end up with a flat list of open items where a missing cable tray label sits next to an exposed live conductor as though they carry equal weight, when they don’t.
Punch List Category Comparison
| PRIORITY | Definition | Gate It Controls | Example |
| Priority A | Safety / critical items or deficiencies that prevent mechanical completion from being declared | Must be cleared before mechanical completion and system energisation | Damaged cable tray compromising electrical safety; missing fire-stopping at a penetration |
| Priority B | Items that do not prevent mechanical completion but must be resolved before commissioning activities begin | Must be cleared before commissioning starts – RFC prerequisite | Instrument not installed to the correct elevation; control valve actuator not connected |
| Priority C | Items that must be resolved before the commissioning completion certificate is issued | Must be cleared before the commissioning completion certificate is issued | Minor damper adjustment required; equipment nameplate missing; scratch on panel |
Priority A items are hard stops. No mechanical completion certificate is issued until every Priority A item is cleared and independently verified. Once Priority A items are resolved and a clear plan is in place for Priority B items, mechanical completion can be declared. From there, the team works through Priority B items to achieve RFC status.
Priority C items may carry forward into and through the commissioning phase, but every single one must be closed before the commissioning completion certificate is issued for the equipment and system.
A practical note: some organisations operate with a four-category system, adding Priority D for disputed items – where the contractor and the commissioning team do not agree on whether the item is a genuine deficiency or acceptable under the contract. If you are working on projects where this comes up frequently, it is worth agreeing the priority rules in the Commissioning Plan at the outset, not on site at 4pm on a Friday afternoon, when the argument starts.
For building systems specifically, Priority A items typically come from HVAC, electrical, and BMS: insulation missing from pressurised pipe work, unprotected electrical terminations, BAS points with no communication. Priority B items are more common in controls and instrumentation: actuators unconnected, sensors not calibrated, access panels not installed. Priority C items tend to show up in fit-out and labelling: missing nameplates, incomplete as-fitted drawings, minor damper travel adjustments.
Who Creates and Manages the Punch List?
The commissioning provider [CxP] or commissioning manager typically owns the punch list and is responsible for its accuracy and integrity throughout the project.
Walk-downs are conducted jointly by the commissioning team, the contractor responsible for the system, and an owner representative, with individual punch items being assigned to the contractor or trade responsible for the deficiency. The commissioning team [CxP] verifies closure, not the contractor.
This independence, the CxP closing the issues, is the critical principle. Under ASHRAE Guideline 0, the CxP maintains the punch list as an independent quality record. The party who raised the deficiency is not the same party who signs it off. That separation is what gives the document its authority and, frankly, what makes it hold up when a contractor disputes an item at handover.
In practice, the commissioning engineer from the CxP conducts the walk-downs for a given piece of equipment or system, raises punch items at point of discovery, assigns them to the responsible contractor, and records the evidence [photographs, instrument readings, drawing references]. The commissioning manager tracks overall punch list status across all disciplines and systems, flags priority gates that are approaching, and escalates items at risk of not closing in time. Who is responsible for commissioning on a project determines exactly how that management chain works.
The owner representative [owner or project manager] attends walk-downs to witness findings and confirm that the acceptance criteria match the original project requirements. Their presence matters: if the owner did not attend the walk-down and later disputes what was found, the record is harder to defend. Walk-down attendance should be formally documented, including who was present and in what capacity.
One thing we consistently see on site: contractor self-certification of punch list closure. The contractor marks the item as resolved and considers it done. Under ASHRAE Guideline 0, that is not acceptable — every item requires independent verification by the CxP before it can be formally closed. Self-certification saves time in the short term and creates disputes at handover. Address this explicitly in the Commissioning Plan.
How Punch List Items Are Closed Out
Closing a punch list item requires three steps: the responsible party rectifies the deficiency, the commissioning team independently verifies the correction is complete and meets the close out requirements, and the item is formally signed off in the punch list register with a date, verifier name, and – where required – photographic evidence. No item can be self-closed by the contractor who raised the work.
The closure workflow, step by step:
| Step | Action | Notes |
| 1 | Contractor notifies the commissioning team that an item is ready for re-inspection | Notification must be formal — email or platform entry — not a verbal conversation on site |
| 2 | Commissioning engineer re-inspects against the original description and design intent | Independent verification — the same party who raised the item should not be the one closing it |
| 3a | If satisfactory: item is marked closed in the register with verifier name, date, and supporting evidence | Formal closure only — no informal sign-off accepted |
| 3b | If unsatisfactory: item remains open and a further response date is agreed | Response date must be recorded in the register, not left as an open comment |
| 4 | Photographic evidence is attached to the record | Required for all Priority A items and Priority B items where the work is not directly accessible post-completion |
Partial or conditional closure applies to Priority B items where a clear, time-bound remediation plan exists: the item is flagged as “conditionally accepted” against the RFC [Ready for Commissioning] gate, with a firm date for full closure before commissioning begins. This is a pragmatic position on complex projects, but it must be formally agreed in writing with the owner representative, not informally nodded through on a morning call. Again be clear in the Commissioning Plan if using this technique.
When a system is ready to be declared RFC, the commissioning manager assembles an RFC document package for submission to the owner or owner’s representative. That package typically includes: the closed punch list [all Priority A and B items verified], signed-off pre-functional checklists, factory acceptance test results where applicable, and any relevant certificates.
Watch for closure drift – items that sit past their priority gate because the contractor is busy with other systems and no one tracks them to resolution. The commissioning manager’s [CxP] role is to prevent this by running a weekly punch list review, publishing the status to all parties, and escalating stalled items before they become a programme risk. A punch list with 30 open items two weeks before handover is a potential sign that the tracking and management failed.
Digital punch list platforms [Procore, Fieldwire, and similar tools] solve a major problem here: cloud-based, photo-enabled, mobile-accessible registers that update in real time for all parties. A shared spreadsheet invites version control failures, proper updates, missed emails, and item statuses.
If your project budget allows, use a dedicated electronic platform.
Punch List vs Snag List – and Other Names You Will Hear
A punch list and a snag list are the same document — referred to by different regional terms. ‘Punch list’ is standard in the United States. ‘Snag list’ or ‘snagging list’ is used in the UK, Ireland, Australia, and New Zealand. In formal commissioning documentation, the document may also be called a deficiency list, issues log, commissioning issues register, or defects register — depending on the contract and the client. The table below sets out the more useful distinction: how the pre-commissioning punch list differs from a general construction snag list in purpose, timing, and the standard required for closure.
Pre-Commissioning Punch List vs Construction Defects List
| Aspect | Pre-Commissioning Punch List | Construction Snag / Defects List |
| Primary purpose | Track system-level deficiencies against design intent and commissioning readiness | Track defects in finishes, installations, and workmanship against contract specification |
| When generated | During pre-commissioning walk-downs – after mechanical completion is approaching | At or near practical / substantial completion – often the final project stage |
| Who manages it | Commissioning authority / commissioning manager | General contractor or project manager |
| Category system | A / B / C based on commissioning phase gates | Usually priority-based \[critical, major, minor\] or trade-based |
| Closure standard | Independent verification by commissioning team required | Often self-certified by contractor with owner sign-off |
In the UK, BSRIA BG 8 [Model Commissioning Plan] and BG 11 [Commissioning Job Book] use the term commissioning deficiencies list – which gives you a sense of how BSRIA frames it relative to broader construction snagging. The terminology is different; the function is the same.
One point that comes up regularly: the pre-commissioning punch list is not a commissioning activity. It is the quality control gate that confirms a system is ready for commissioning to begin. It runs before functional testing starts, not alongside it.
