What happens when we cut costs where nobody looks?

When budgets get tight, the hidden parts of a building can become tempting places to save money, but cutting the cost of components that nobody sees can create some of the most expensive problems in construction, writes John Ridgeway.

Walk into a newly completed building and the expensive decisions are obvious. The stone flooring, kitchens, sanitaryware, lighting, doors and finishes are all there for the client to see, but behind them is another building that receives far less attention.

There are membranes protecting against water, insulation controlling heat loss, fire-stopping protecting compartmentation, fixings holding systems together, brackets supporting services, pipes carrying water and cables carrying power and data. Most of it disappears behind walls, above ceilings and beneath floors.

That creates a particular temptation when a project is under financial pressure - if the client will never see it, can it be bought more cheaply? The problem is that the hidden components are often the ones responsible for making the visible building perform and when they fail, the cost can be considerable.

The cheapest component can become the most expensive decision

Construction is under constant pressure to control costs. RICS reported in Q1 2026 that financial constraints were cited by 66% of respondents as a factor limiting activity, while respondents expected construction costs to rise by 6.6% over the following year and material costs by 7.5%. Those pressures inevitably influence procurement decisions.

Value engineering has an important role to play. There is nothing wrong with finding a more efficient product or eliminating unnecessary cost. The danger comes when price becomes the dominant consideration for something whose performance is critical but invisible.

A cheaper membrane may look identical to a more expensive one. A lower-cost fixing may perform perfectly well under normal conditions. A different fire-stopping product may appear to do the same job. However, the difference often becomes apparent only when the component is tested by water, fire, movement, temperature or time and by then, the wall may be finished and the ceiling closed.

There is substantial evidence that construction errors are far more expensive than they appear when the original decision is made. The Get It Right Initiative, which brings together major clients and construction organisations, cites research putting the average direct cost of rework at around 5% of total construction costs. It also identifies cost pressures and time pressures among the principal root causes of construction errors. Its research concludes that the total cost to the UK industry is substantially higher than £5bn a year once indirect costs are included – and that is the important distinction.

The issue is that the opening example jumps straight into fire-stopping without explaining why it is the relevant example. I’d make the transition more explicit and let the second paragraph naturally introduce the example:

Saving £2,000 on a hidden component may look like good procurement, but if that component fails after the wall has been closed, the apparent saving can quickly become a £20,000 repair - or considerably more if the problem has spread through the building.

Fire-stopping is one of the clearest examples of this risk because, once a building is finished, it is almost completely invisible. Services pass through compartment walls and floors, creating openings that must be properly sealed to maintain the building’s fire performance. The correct product matters, but so do the installation method and the construction around it. Get any of these wrong, and a component that seemed like a small procurement decision can become a significant safety, compliance and cost issue.

RICS reported in 2026 that common fire-stopping defects include missing fire-stopping, unsuitable products, incorrect specification and chemical incompatibility. It also warns that many defects remain hidden in difficult-to-access areas and may not be identified through a standard due-diligence survey. This is where the economics of cheap procurement can become particularly uncomfortable.

A product can be cheaper because it is cheaper to manufacture, easier to install or available from a different supplier, but if it has not been assessed for the particular application, or is installed incorrectly, the saving is meaningless. The finished wall won't tell you whether the fire-stopping behind it is correct and we have already seen the consequences

The post-Grenfell building safety regime has demonstrated the enormous financial consequences that can follow when building products and systems fail to deliver the required performance.

Government data published at the end of 2025 identified 2,497 buildings 11 metres and over with life-critical fire safety defects under the developer remediation programme. The estimated cost of remediating those buildings was around £4.2bn, with approximately 153,000 dwellings affected.

It would be wrong to suggest that these defects were all caused by somebody choosing a cheaper product. The causes are far more complex, but they demonstrate a fundamental point, that the cost of getting hidden construction products and systems wrong can be measured in billions, not thousands.

The Government's current construction-products reform programme also acknowledges that the Grenfell Inquiry exposed systemic failures in the UK's construction-products regulatory system.

Water doesn't care what the product cost

The same principle applies to waterproofing. A membrane hidden behind a wall or beneath a roof covering may be one of the least visible elements of the building, yet its performance can determine whether the building remains dry.

NHBC's latest guidance identifies failures involving damp-proof courses, membranes and drainage among common defects, with improper detailing and rushed installation among the contributing factors. It also highlights roofing and weatherproofing failures caused by incorrect installation and inadequate technical understanding.

Water ingress is particularly unforgiving because it can remain hidden. A small failure behind a finished wall may go unnoticed for months, allowing insulation, plasterboard, timber and finishes to become damaged. What began as a membrane failure can then become a costly process of investigation, opening up, replacement and reinstatement.

Quality is difficult to value when you can't see it

This is the procurement challenge. A client can easily compare two visible finishes, but comparing membranes, fire-stopping or insulation systems is far harder. That makes the specification critical. What is the product designed to do? Has it been tested for the application? What certification supports it? How should it be installed, and what happens if another trade interferes with it? These questions matter far more than whether one product is £5 cheaper.

The answer isn't simply to specify the most expensive product. A premium product that is unsuitable for the application is still a poor choice, while a lower-cost product may deliver excellent performance if it has been properly tested, specified and installed. The objective should be value, not simply price.

That means looking beyond the purchase cost to service life, installation, maintenance, inspection and the potential cost of failure. It also means considering what documentation will remain when the building changes hands.

Hidden components deserve particular attention because, once covered, inspection becomes much harder. Fire-stopping can be checked before a wall is closed. Membranes can be inspected before the next layer is installed. Services can be photographed and recorded before they disappear above a ceiling.

Once covered, finding a problem may require destructive investigation. NHBC offers inspections covering areas including fire-stopping, cavity barriers, cavity trays and roof abutments, recognising the value of identifying problems before they become concealed. The principle is simple - inspect what you won't be able to see later while you still can.

Construction will always involve pressure on cost, but invisible components should not automatically become targets for savings. They may be precisely where performance matters most.

The cheapest decision often looks cheapest when it is made. The consequences arrive later, when the wall is closed, the ceiling is finished and the component that caused the problem is the one thing nobody can see. The best time to save money on a hidden component is before you buy it. The worst time is after you've buried it in the building.

Absolutely. I’d make the FAQs reinforce the article without simply repeating its wording:

FAQs

1. Why are hidden construction components important?
Hidden components such as membranes, insulation and fire-stopping may be critical to a building’s performance but are difficult to inspect once covered. If they fail, finding and repairing the problem can be far more expensive than getting the specification and installation right initially.

2. Should construction products always be chosen on price?
No. The lowest purchase price does not necessarily represent the best value. Performance, suitability, certification, installation requirements, expected service life and the potential cost of failure should all be considered when comparing products.

3. What should be checked before specifying a construction product?
Consider what the product is designed to do, whether it has been tested for the intended application, what certification or third-party assessment supports it, how it should be installed and whether it is compatible with the surrounding construction.

4. Why is fire-stopping particularly important?
Fire-stopping helps maintain compartmentation by sealing openings around services and other penetrations. Because much of it becomes concealed, correct product selection, installation and inspection are essential before walls, floors or ceilings are closed.

5. Why should hidden components be inspected before they are covered?
Once concealed, defects can be difficult to identify without opening up the building. Inspecting membranes, fire-stopping, cavity barriers and service installations before they disappear from view can identify problems when they are still relatively straightforward to rectify. 

6. What is whole-life value in construction procurement?
Whole-life value considers more than the initial purchase price. It takes account of factors such as installation, durability, maintenance, inspection, repair and the potential consequences of failure over the building’s life. 

7. Can a cheaper construction product still be the better choice?
Yes. A lower-cost product can offer excellent value if it is suitable for the application, properly tested, correctly specified and installed. The issue is not whether a product is cheap, but whether it delivers the required performance.

8. What can happen if water ingress remains undetected?
Moisture can damage materials such as insulation, plasterboard, timber and finishes. The longer a problem remains hidden, the greater the potential for extensive remedial work, including investigation, opening up, replacement and reinstatement.

9. Who is responsible for checking hidden construction elements?
Responsibility depends on the project and contractual arrangements, but quality assurance should clearly identify who is responsible for inspecting, recording and signing off critical elements before they are concealed. Clear ownership and checking processes can reduce the risk of defects being carried forward.

10. What documentation should be retained for hidden components?
Where appropriate, records should include product information, test evidence, certification, installation details, inspection records and photographs. This provides evidence of what was installed and can be valuable for future maintenance, alterations or investigations.

11. Is it more expensive to inspect hidden components during construction?
There is a cost to inspection, but it can be small compared with the cost of discovering a defect after construction is complete. Some failures may require intrusive investigation and significant opening-up and making-good works. 

12. How can construction procurement reduce the risk of hidden defects?
Start by specifying performance rather than simply price, verify product suitability and certification, define installation requirements and responsibilities, and inspect critical components before they are covered. The aim should be to prevent expensive problems rather than simply reduce the initial purchase price.