Snagging Guide for UK Builders and Contractors — How to Manage Defects and Protect Your Retention (2026)

What is snagging?

Snagging is the process of identifying and rectifying defects or incomplete work at the end of a construction project. It applies across the board — new builds, house extensions, commercial fit-outs, bathroom renovations, kitchen installations. The term comes from the idea of catching small issues before they become larger problems or disputes.

In practice, snagging typically happens just before or immediately after practical completion. A walkthrough of the finished works is carried out, a list of outstanding items is produced, and the contractor is given a period to rectify them. The list might include anything from a door that doesn't hang level, to a patch of uneven plasterwork, to a tap that wasn't connected properly, to missing silicone around a bath. No job is entirely snag-free — the question is how you handle the list.

It's worth distinguishing between a defect and incomplete work. A defect is something that was done but not to the required standard. Incomplete work is something that simply hasn't been done yet. Both appear on snag lists, but they arise for different reasons and the paper trail you need differs accordingly.

Who carries out the snagging?

This depends heavily on the type of project and the contract in place.

On domestic projects — extensions, refurbishments, single-trade work — snagging is usually carried out by the client themselves, or by a snagging surveyor they've hired independently. Many homeowners now pay specialist snagging companies to inspect the work before signing off, particularly on new build purchases. These surveyors are experienced at finding issues, and their reports tend to be thorough.

On commercial projects, the snagging walkthrough is typically led by the contract administrator, architect or project manager — whoever is named as the employer's agent under the contract. They produce a defects schedule and issue it formally to the contractor.

As a contractor, you may find yourself on either end of this process. On a direct domestic job you're the one being snagged. On a larger project as a main contractor, you may be compiling snag lists for your own subcontractors. Either way, the principles are the same: get it in writing, be systematic, and keep the documentation.

Defects liability periods and retention — how they work

Most formal construction contracts — JCT, NEC, or bespoke commercial agreements — include a defects liability period (DLP). This is a defined window of time, typically six to twelve months after practical completion, during which the employer can notify the contractor of defects and require them to return and fix them. After the DLP ends and all notified defects have been rectified, the contract administrator issues a certificate of making good defects, and the remaining retention is released.

Retention is the mechanism employers use to incentivise completion and defect rectification. Under most standard contracts, the employer withholds a percentage of each interim payment — typically 5% of the contract value — as security. Common release structures work like this:

• Half of the retention (2.5%) is released at practical completion
• The remaining half (2.5%) is released at the end of the defects liability period, once all defects have been made good

On a £200,000 contract, that means £10,000 in retention — £5,000 released at practical completion and £5,000 held for the duration of the DLP. That second £5,000 can sit with the employer for twelve months or more, and it will only come back to you if you manage the process actively.

The DLP is not a guarantee period in the consumer sense. It's a contractual obligation to return and fix defects that are notified within the period. Defects arising after the DLP ends are generally your liability under common law (negligence, breach of contract) but the retention mechanism no longer applies. This distinction matters — defects notified after the DLP cannot be used to justify withholding the retained amount.

On domestic work without a formal contract, no DLP exists in the technical sense — but the Consumer Rights Act 2015 still applies. Work must be carried out with reasonable care and skill. If it isn't, the client has up to six years to bring a claim. This is why documentation matters even on small domestic jobs.

Do your own snagging before handover

The most effective thing you can do before a handover walkthrough is walk the job yourself, ideally a day or two before the client inspection. Take your time. Bring a notepad and your phone. Photograph every room, every surface, every detail. If you spot something — a chip in a tile, a bit of filler that needs touching up, a light fitting that's not quite flush — fix it before the client sees it.

This approach pays for itself many times over. A client who sees a clean, finished job is far less likely to go looking for problems than one who spots three obvious issues on the way through the door. First impressions in the final walkthrough are powerful. If a client's opening experience is "there's a crack in the skirting," they will scrutinise everything else. If their opening experience is "this looks great," they're far more likely to be generous in their assessment.

Producing your own walkthrough report — even an informal one — is also useful. It shows professionalism, it demonstrates that you take quality seriously, and it gives you a dated record of the condition of the work at handover. If a defect is claimed six months later that you photographed as non-existent at handover, that documentation is valuable.

Managing the snagging process professionally

The handover walkthrough is a business meeting, not a conversation. Treat it that way.

Walk the job with the client or contract administrator. For each item they raise, either agree it's a legitimate defect and note it down, or politely push back if it isn't (more on that distinction below). At the end of the walkthrough, produce a written snag list that both parties sign. Each item should have a brief description and an agreed completion date. This is your contract for the snagging phase — without it, items can be added retroactively, completion dates are disputed, and you have no basis for claiming the job is done.

Do not agree to verbal snag lists. "I'll just send you a few things by email" is a route to a drip-feed of complaints over weeks. The walkthrough is the time to capture the full list. Anything raised after it should be evaluated carefully — is it a new defect, or something that was visible at walkthrough and not mentioned?

Once the list is agreed, work through it systematically. Keep dated records of when each item was completed — a photo with a timestamp is sufficient for most items. When you believe all items are done, contact the client formally and request a re-inspection. Don't just assume the job is closed because you've done the work.

Defect or variation — knowing the difference

One of the most common sources of snagging disputes is the blurring of genuine defects with client preference changes. Understanding the distinction is essential.

A genuine defect is work that was not done to specification, does not meet building regulations standards, or used materials that were defective or not as specified. Examples: tiles that have cracked due to inadequate adhesive; a wall that isn't plumb to within tolerance; a circuit that doesn't comply with BS 7671; pipework that leaks. These are your responsibility to rectify at your own cost.

A variation is a change from what was originally agreed. The client decided halfway through the project that they want a different tile, a door that swings the other way, or an extra socket in a location not on the original plan. If the client agreed to a specification and you delivered it, the fact that they've changed their mind does not make it a defect. It's a variation — a new instruction — and it should be priced and agreed as such via a variation order before you do any additional work.

This distinction becomes contentious when a client agreed to something verbally during the job ("yeah, that's fine") and then raises it as a snag at the end. This is exactly why variation orders need to be documented in writing at the time, not reconstructed from memory. If a client asked for a change and you have a message or email confirming it, that protects you. If it was a verbal chat and nothing was written down, you're in a harder position.

When a client raises something at snagging that you believe is a variation, say so calmly and clearly. Explain that the original specification required X, you delivered X, and what they're now describing is a change to the original scope. If they disagree, note the dispute and move on — don't agree to do the work free of charge while the disagreement is unresolved.

Protecting your retention

Retention is not automatically returned. You have to actively chase it, and you have to document everything that justifies its release.

Before you start any project with a retention clause, check that the contract is specific about when retention is released and what triggers the release. The two key events should be clearly defined: practical completion (triggering the first half) and the end of the defects liability period with all defects made good (triggering the second half). If your contract is vague about this, push back before you sign it.

During the DLP, keep a dated record of every defect that is notified to you, every visit you make, and every item you rectify. Photograph the before and after for each item. This documentation is your evidence that you fulfilled your obligations — it's what you use to demand the final retention release.

At the end of the DLP, issue your final account claim promptly. Don't wait for the employer to come to you. Issue a formal notification that the DLP has expired, all notified defects have been rectified, and you are due the release of the outstanding retention. Attach your evidence — dated photos, correspondence confirming each defect was resolved.

Many contractors lose retention simply through inaction. They finish the job, get the first retention release, and then let the DLP drift by without following up. A year later the project is a distant memory, the employer is busy on other things, and the retention sits unclaimed. Set calendar reminders. Diarise the DLP end date from the day you reach practical completion.

Snagging as a subcontractor on new build sites

If you work as a subcontractor on larger new build or commercial sites, snagging and retention work the same way — but your relationship is with the main contractor, not the end client. This adds a layer of complexity.

The main contractor holds your retention, not the developer or employer. Your subcontract should specify the DLP, the retention percentage, and the trigger for release. Many subcontracts mirror the main contract — meaning your retention isn't released until the main contract defects are signed off, which could be well after your own DLP has expired. This is a commercial risk worth understanding before you sign.

Main contractor snag delays cascade directly down the supply chain. If the main contractor is struggling to get sign-off from the employer — perhaps because of defects in other packages, or a dispute with the architect — your retention sits in limbo even if your own work has been faultless. Stay in contact with the main contractor's commercial team throughout the DLP. Know the status of the overall project sign-off. Don't assume that because your package is finished, your retention is safe.

If your sub-contract allows it, consider whether retention bonds (where a surety provides the security rather than cash being withheld) are something you can negotiate. They aren't common on smaller packages, but on larger subcontracts they remove the cash flow impact of having a percentage of your earnings held for twelve months or more.

When clients use snagging to avoid paying

This happens. A client with an exaggerated snag list can hold up a final payment almost indefinitely if you let them. The pattern usually looks like this: you finish the job, present your final invoice, and are suddenly presented with a long list of issues — some legitimate, many questionable, a few invented. The implicit message is that payment will follow once every item is resolved to the client's satisfaction, which somehow never happens.

The way to respond is methodical, not emotional. First, agree in writing which items on the list are genuine defects and which you dispute. You don't have to accept the whole list. For disputed items, set out your position clearly in writing — is it a variation? Is it within tolerance? Did they raise it at handover or only after payment was due?

Work through the agreed defects systematically. For each one, complete it, photograph it, and confirm in writing that it's done. Request a re-inspection for that item. Build a paper trail that demonstrates you are fulfilling your obligations promptly and professionally. This documentation is your protection if the matter escalates.

Once all agreed defects are rectified, issue a formal demand for payment of the outstanding sum. If payment isn't forthcoming, the Housing Grants, Construction and Regeneration Act 1996 (as amended by the Local Democracy, Economic Development and Construction Act 2009) gives contractors a powerful right: adjudication. Any party to a construction contract has the right to refer a dispute to an adjudicator at any time. The adjudicator's decision is binding in the interim — the losing party must pay before any further appeal — which makes it a fast and effective route to resolution on retention and final account disputes.

Note that the Housing Grants Act applies to commercial construction contracts. On pure domestic contracts (where the employer is a residential occupier having work done on their home), the Act's adjudication provisions don't automatically apply — though many solicitor-drafted domestic contracts include adjudication clauses anyway. On domestic jobs without such a clause, you're looking at mediation or the county court. Either way, having a solid paper trail from the snagging process is what makes your case.

Key takeaways

• Snag your own job before the client does — fix obvious issues before the walkthrough.
• Always get a signed, written snag list at the handover walkthrough. No verbal lists.
• Know the difference between a defect (your liability) and a variation (an instruction that needs a variation order).
• Document every defect rectification with dated photos — this is what unlocks your retention release.
• Diarise your DLP end date on day one and chase retention proactively — it won't come automatically.
• As a subcontractor, understand how your retention is tied to the main contract sign-off — and plan your cash flow accordingly.
• If a client is using snagging to avoid paying, build your paper trail and use adjudication if needed.