What is a Technical Inspection Service (TIS)?

A Technical Inspection Service (TIS) is an independent technical inspection of a building project, in which a specialist firm checks the design and construction on a risk basis. The TIS is not a party in the building process: it does not design or build, it only assesses. This allows it to judge impartially whether the work is technically sound.

Origin: insurance against building defects

The TIS is known from the world of IDI insurance (Inherent Defects Insurance): a policy that covers damage caused by hidden defects, for example in the structure or waterproofing, after completion. The insurer wants to be sure the risk is manageable and therefore has a TIS follow the project. In countries such as France, technical inspections of this kind have long been common in connection with the ten-year (decennial) liability of builders.

Dutch example

In the Netherlands, Instrument TIS was approved in 2022 as a quality assurance instrument under the Dutch Quality Assurance for Building Act (Wkb). A quality assurer working with this instrument assesses whether the building complies with the Dutch technical building regulations.

How it works in outline

1. Risk analysis: which parts of the design and construction are critical, such as foundations, structure, fire safety and waterproofing?
2. Design review: drawings and calculations are checked against those risks.
3. Site inspections: at critical moments, for example before an element is covered up.
4. Reporting and final statement: findings are recorded, and shortcomings must be resolved before the work is completed.

Tips for clients

• Agree in advance when inspections will take place, so that the construction programme allows for them.
• Make sure drawings and calculations are complete in good time: a TIS can only assess what it is given.
• An inspection does not replace the contractor’s own quality control.

Related terms

• Consequence class
• Structural engineer
• Fire resistance
• Construction costs

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