Andrew Pemberton, chartered building engineer and senior manager of surveying at The Professional Snagging Company, argues that early defect detection in construction is critical for reducing operational costs and fixing problems more quickly
Most defects don’t arrive looking serious. They start as small oversights: a missed tolerance, a rushed check, something that looked fine at the time. Left alone, those small things grow into costly rework. Research puts rework at somewhere between 2% and 12% of total construction costs, depending on the project. A wide range, but even the lower end is significant for homeowners.
Early defect detection in construction decreases the chances of this happening. It moves the focus from reacting to problems to catching them while they’re still cheap and straightforward to resolve.
This article looks at what that means in practice, why it matters commercially, and how to build a process that works on a real site.
Why timing changes everything
Take something as simple as a waterproofing issue. If it’s picked up while the area is still open and accessible, a competent team can sort it in hours. Wait until the project finishes, and you’re now stripping back completed work just to get to the problem. Wait until the building is occupied and you’ve got tenants to manage and complaints to handle on top of the actual repair cost.
The same applies to almost any defect. The longer it goes undetected, the more it gets built over, built around, or built upon. Fixing it stops being a costly job and starts becoming a project.
This is why timing is the most important variable in defect management. It’s not just about finding problems. It’s about finding them early enough, so they don’t become expensive.
What early defect detection looks like
Early defect detection in construction isn’t just better snagging. Snagging happens at the end. Early detection happens throughout the build.
In practice, that means three things. First, issues should be reviewed at the design stage before they reach the site. Clashes between different elements of a building, things that look fine on paper but don’t work, are far cheaper to resolve in a meeting room than on a live site.
Second, materials and specifications should be checked at the procurement stage. If something doesn’t meet the requirement, that needs to be flagged before it’s ordered, delivered, and installed, not after. A common example is the substitution of insulation with a cheaper alternative, such as expanded polystyrene (EPS).
Third, checks should happen at installation, before work is covered up. Once a wall is closed or a floor is finished, what’s behind it becomes very difficult to verify. Building inspection at that stage, as a normal part of the process rather than an afterthought, is where many late defects are prevented.
The shift in mindset is this: early detection isn’t about finding more defects; it’s about finding patterns sooner. If the same issue keeps appearing in the same type of area, that’s a process or specification problem, and it needs fixing at the source, not patched repeatedly as it keeps showing up.
The defects that matter most
Not every defect carries the same risk. The ones worth focusing on early share a common trait: they get harder to fix the longer they’re left.
Hidden defects, things like insulation gaps or poorly installed fire protection, disappear behind completed work. Once covered, you often can’t verify them without a destructive investigation. Even opening up a single wall to inspect can cost upwards of £2,000. Catching these before they’re concealed is the only practical window.
Repeated defects are the other major category. Where a building has identical units or repeated layouts, one missed issue can quickly become the same issue in twenty places. Spotting it in the first unit and correcting the approach saves it from multiplying across the rest of the build.
Why are defects still found late
The majority of late defect detection doesn’t stem from bad workmanship. They come down to gaps in the process.
The most common causes are unclear instructions before work starts, materials that don’t match the specified requirements, and rushed or skipped inspections to maintain progress with a deadline in sight. There’s often a cultural pressure on site to keep moving; everyone wants to get jobs done as quickly as possible. This means checks get forgotten about, and problems get buried under the next phase of work.
Documentation is another weak point. Problems get logged but are not properly understood. A photo without context, or a note with no clear owner, doesn’t close anything out. It just creates problems further down the line with people not understanding the full extent of the issue.
The practical fix is straightforward: build inspection into the programme as a fixed step, not an optional one. Define who is responsible for sign-off. Make it harder to skip a check than to do it.
Building a process that holds
The projects that manage quality well tend to have one thing in common: inspection is part of the job, not something that happens around it.
It starts before work begins. Everyone on site needs to know what good looks like before they start, not find out it was wrong after the fact. Vague expectations are among the most common causes of defects, and in most cases, they’re entirely avoidable with a conversation that should’ve happened at the start.
From there, it’s about keeping a simple habit through the build. Check before starting a new section, review the first completed area thoroughly, and make sure nothing gets covered up before someone has signed off on it. When something isn’t right early on, that’s the moment to sort the approach out, before the same issue runs through the rest of the job.
When a problem is raised, it needs an owner and a proper close-out. Not a note on a system that sits unresolved for three weeks, an actual resolution that someone has verified. That distinction sounds obvious, but it’s where many processes fall apart.
Digital tools can help keep track of all this, and some do it well. But no software fixes a site where nobody’s really checking. The tool is only as good as the process behind it.
Exploring more options with early defect detection
The earlier a problem is found, the more options you have: a quick fix, a process adjustment, a conversation with a supplier.
Leave it too long, and those options disappear, replaced by rework costs, programme pressure, and damaged trust with the client.
The projects that handle quality well don’t rely on a final sweep to catch everything. They make inspection a normal part of how work gets done, and they act on what they find quickly enough to stop problems from repeating.
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