Published6 May 2026Updated5 October 2026
Snagging: What It Is, What It Isn’t, and Why the List Shouldn’t Come as a Surprise to Anyone
The snagging list is one of the most reliably contentious moments in any construction project. Clients arrive with highlighters. Builders arrive with patience already thin. Most of the arguments that follow are avoidable — if everyone agreed upfront what ‘finished’ actually means. A plain-English guide to what a snag is, what isn’t one, and how JSA approaches it.
The snagging list is one of the most reliably contentious moments in any construction project. Clients arrive with highlighters. Builders arrive with patience already thin.
Snagging is the part of a construction project that everyone knows is coming and almost no one handles well. Clients arrive at practical completion with a list that took three evenings to compile and strong feelings about every item on it. Builders arrive having spent several months delivering a project and with a different view of what constitutes a defect. The architect sits in the middle, trying to apply a consistent standard to a conversation that was never clearly defined.
So here, we're setting out what snagging actually involves, what the relevant standards say, and where most of the friction comes from. It also explains something JSA builds into its tender documentation that most practices don't - and which makes the end of a project considerably less contentious for everyone involved.
snagging / noun — The moment at the end of a construction project when the architect, the contractor, and the client each discover they had a slightly different building in mind.
Snagging is the process of identifying items of work that fall short of the standard required under the building contract. When a contractor reaches practical completion, the building is considered finished to the degree that the client can occupy and use it. Remaining defects - snags - are then recorded and the contractor is required to return and remedy them within a defined period.
Under a standard JCT contract, this period is typically three or six months, though it can be set to twelve months or another agreed duration. During this defects liability period, the contractor remains responsible for making good any defects that arise or are identified. At the end of the period, the architect issues a certificate of making good, and the remaining retention held under the contract is released.
That is the process. The difficulty lies not in the process but in the question the process depends on: what counts as a defect?
When is a Snag....a Snag?
A defect (in the contractual sense), is work that does not conform to the specification or workmanship standard required by the contract. Not work that the client would have preferred to be done differently. Not work that falls below an aspirational standard the client had in mind but never specified. Not natural variation in materials, or the visual characteristics of hand-applied finishes, or minor movement in timber that is behaving exactly as timber does.
This distinction matters because snagging lists frequently contain all of these things mixed together - genuine defects alongside personal preferences and items that represent a misunderstanding of how buildings behave. A builder presented with a list of forty items, twenty of which are legitimate defects and twenty of which are not, is not going to respond with the same goodwill as one presented with a list of twenty items that are all clearly valid.
The most useful thing an architect can do in this situation is distinguish between them clearly and early. That means understanding the relevant standards well enough to make the call with confidence in both directions.
The Standards That Set the Baseline
Workmanship standards in UK construction are not left to subjective judgment. There are published references that define acceptable tolerances for most common elements of building work.
BS 8000 is the principal British Standard for workmanship on building sites. It runs across multiple parts, covering areas including earthworks, concrete, masonry, waterproofing, carpentry, joinery, glazing, plastering, rendering, floor screed, tiling, and painting. Each part sets out the standard of workmanship expected and, in many cases, specific tolerances - maximum permissible deviation from a surface, gap size, joint alignment, and so on.
For residential new builds, NHBC Standards can provide detailed guidance on workmanship tolerances and inspection criteria. Chapter 3 of the NHBC Standards covers a wide range of finish elements, with specific numerical tolerances for wall flatness, floor levelness, door alignment, and similar items. These are the figures a contractor can reasonably be held to, and the figures a client can reasonably expect - no more and no less.
For example: under NHBC guidance, a plastered wall may have a surface deviation of up to 5mm when measured over a 1.8-metre straightedge. That is not a perfect wall — but it is a wall that meets the standard for a standard residential finish. A client who expects a perfectly flat surface without specifying a higher standard is expecting something that was never contracted for.
The same principle applies in commercial construction, where the relevant British Standards, manufacturer specifications, and any project-specific requirements set out in the specification documents define what the contractor has agreed to deliver.
Understanding these standards does not mean defending poor work. It means being in a position to distinguish poor work from acceptable work - and to explain the difference to a client in terms they can rely on.
Where Most of the Friction Comes From
The majority of snagging disputes do not arise because the contractor has done poor work. They arise because the expected standard was never explicitly agreed.
A client who has spent a significant sum on a building project has every right to expect a high-quality result. The question is: what does ‘high quality’ mean in practice? For a standard finish, BS 8000 and NHBC tolerances provide the answer. But for areas of the building where a higher standard has been agreed - a premium painted finish, a bespoke joinery item, a feature wall with specific flatness requirements - the standard specification may not be sufficient. If no higher standard was written into the contract, the contractor cannot reasonably be held to one.
This is where the snagging list becomes a source of genuine disagreement rather than a straightforward process. The contractor believes they have delivered what was specified. The client believes they have paid for something better. Both may be right, in their own terms. But without a written standard to refer to, the conversation has no anchor.
How JSA Approaches It: Specifying the Standard Before Work Begins
JSA includes quality standards directly in its tender documentation. This is not standard practice across the industry, and it makes a material difference at the end of a project.
Where a project requires a higher level of finish than the default workmanship standard - in areas such as plastering, painting, tiling, joinery, or any other finish-critical element - JSA writes the required standard into the specification before a contractor is appointed. This means the contractor prices for it, agrees to it, and is bound by it. At practical completion, the standard that applies is the one written in the documents, not the one assumed by either party.
In practice, this means being specific. Not ‘high-quality painted finish’ - a phrase that means nothing to anyone at the inspection stage - but a defined tolerance for surface preparation, the number of coats required, the acceptable level of sheen variation under raking light, and the method for assessing compliance. For plastering, not ‘smooth finish’ but a stated maximum deviation measured over a defined straightedge length, consistent with or exceeding the relevant British Standard, depending on what the project requires.
The same approach applies to any element where the default standard is insufficient for the project. Bespoke joinery items may have specific gap tolerances written in. Tiling layouts may have defined grout joint tolerances. Painted steelwork may reference a specific surface preparation grade and coating system.
This level of specification serves both parties. The contractor knows exactly what they are being asked to deliver. If they have priced correctly, they will deliver it. If there is a dispute at practical completion, there is a written document to refer to rather than a conversation about expectations that nobody can quite remember.
For clients - whether a homeowner completing a renovation or a developer taking handover of a commercial scheme - it means the snagging inspection has a clear basis. Items that fall below the specified standard are defects. Items that meet it are not. The inspection becomes a technical exercise rather than a negotiation.
What a Reasonable Snagging Inspection Looks Like
A thorough snagging inspection covers the full scope of the works systematically. Each trade, each room, each element of the building envelope is checked against the specification. Items are recorded clearly - location, description, the standard not met, and what remedy is required.
A well-prepared snagging list is not a long list. It is an accurate list. Twenty legitimate defects, clearly described, will be taken more seriously by a contractor than eighty items of mixed validity. A list that conflates genuine defects with personal preferences and items that represent normal material behaviour makes the contractor’s job harder and the resolution process slower.
On a residential project, common legitimate snags include: incomplete decoration at junctions and reveals, minor tile lippage beyond specified tolerance, ironmongery not correctly adjusted, services not commissioned or demonstrated, outstanding certification not provided, and minor mechanical damage incurred during the final stages of work. Less common but also legitimate: structural cracking beyond hairline, water ingress, failing seals, and any element of work that demonstrably fails to perform its intended function.
On a commercial project, the same principles apply at a larger scale. Mechanical and electrical commissioning records, O&M manuals, as-built drawings, and warranties are all part of what practical completion requires. A building may look finished and still have outstanding contractual obligations that prevent the defects liability period from starting cleanly.
Equally, some things that appear on snagging lists are not defects. Hairline shrinkage cracks in plaster are normal and expected — they are a characteristic of the material drying out, not a failure of workmanship. Minor thermal movement in timber is not a defect. A colour appearing slightly different under different lighting conditions is a property of paint, not evidence of a substandard application. These distinctions are not obscure - they are the basis on which any fair snagging inspection should operate.
The Defects Liability Period Is Not an Excuse to Defer Completion
One point worth being clear about: the defects liability period exists to capture latent defects - items that were not apparent at practical completion but emerge during the period of occupation. It is not a mechanism for continuing to fit out a building after handover, or for adding items to the list that were not present at the original inspection.
The inspection at practical completion should be as complete as possible. Items identified later in the liability period should genuinely be items that were not visible or could not have been identified at the time. The defects liability period is a protection for the client, not a substitute for a thorough inspection at handover.
For contractors, this means the liability period represents a defined and finite obligation - not an open-ended commitment to revisit the site whenever a new concern arises. For clients, it means the practical completion inspection is the time to look carefully, not to assume that anything missed can always be added later.
The Outcome Everyone Wants
Builders want to finish the job, get paid, and move on. Clients want a building that performs as expected and looks as agreed. Neither of these objectives is unreasonable, and in most cases they are not in conflict.
The snagging process goes wrong when the standard was never agreed. It goes right when both parties know what was specified, what was delivered, and what the small number of outstanding items are that need to be resolved.
That is the outcome JSA works toward. Not a snagging list that is impossible to dispute, or one that waves through substandard work. A snagging list that reflects the actual position at the end of a project, applied to a standard that was written down at the beginning.
Areas We Cover
JSA Architects Across the Midlands
We work with homeowners, developers, and landlords across the Midlands. Fees, planning authorities, and project types vary by location — find local insight and project examples for your area:
Architects in Derby → — Quarndon, Kirk Langley, Duffield, Allestree, Darley Abbey, Mickleover, Littleover
Architects in Nottingham → — The Park Estate, West Bridgford, Edwalton, Mapperley Park, Wollaton, Bramcote
Architects in Lichfield → — Shenstone, Little Aston, Four Oaks, Streetly, Aldridge, Walsall, Tamworth, Whittington
Architects in Solihull → — Knowle, Dorridge, Hampton in Arden, Shirley, Dickens Heath, Olton
Architects in Sutton Coldfield → — Four Oaks, Wylde Green, Boldmere, Mere Green, Streetly, Little Aston
faq's
Common Questions
Snagging is the process of identifying items of work that fall short of the standard required by the contract, specification, or Building Regulations, at or near practical completion.
A defect, in the contractual sense, is work that doesn't conform to the specification or to the standards that govern UK construction workmanship. Not every complaint on a homeowner's list meets that bar; that's usually where the friction starts.
Workmanship standards aren't left to subjective judgement. There are published British Standards and, for new-build warranties, NHBC-style technical standards that define what 'finished properly' actually means.
No. The defects liability period exists to capture latent defects that only surface after occupation, not to excuse a contractor from finishing the original scope to standard before practical completion.
By specifying quality standards directly in the tender documentation before work begins, so everyone is measuring the finished building against the same agreed standard rather than arguing about it after the fact.
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