Buildings and structures that have 'functioned' well enough for years often no longer comply with the standards and directives for new constructions. This is good reason to once again look at the construction of a building or structure. TNO Built Environment and Geosciences regularly investigates the constructive safety of existing building structures.
Our investigations reveal that complete renovation or demolition is not necessary in many cases. Buildings are often able to comply with the regulations with little or no modification. But expertise is required to establish this. TNO knows what underlies standards and directives like the NEN 6700 series (on the reliability of building structures) and the Buildings Act, and knows how to interpret them correctly. For existing constructions lower safety factors can be tolerated, for instance, at the same level of safety for which the construction had earlier complied with the standards then in force. This is possible because existing constructions tend to have a shorter lifetime than new constructions.
Another example is assurance about the material properties and the stresses on the construction. The jury is not yet out on the new constructions but for existing constructions much more is known, and the stresses can be measured. It is also clear whether the construction has survived the stresses of the past, and that removes a lot of insecurity. So measurements and practical experience give some assurance and thus a higher degree of reliability and/or safety.