Structural damage and the decennial guarantee

What the decennial guarantee covers

The Spanish Building Act, Law 38/1999 (Ley de Ordenación de la Edificación, LOE), sets three liability periods, counted from the handover of the works:

• Ten years for damage caused by flaws or defects affecting the foundations, supports, beams, floor slabs, load-bearing walls or other structural elements, and which directly compromise the mechanical strength and stability of the building.
• Three years for defects in construction elements or installations that affect habitability.
• One year for finishing defects, for which the contractor is liable.

In residential buildings, the ten-year liability must be guaranteed by material damage insurance: decennial insurance.

The key: compromising stability

It is not enough for there to be damage to a structural element: the law requires that it directly compromises mechanical strength and stability. A hairline crack in a beam or a deflected floor slab may be a nuisance, spoil the appearance or break partition walls, and still not put stability at risk.

That is why, when damage appears, the technical question is not just ‘is there damage?’ but ‘where does the structure stand in terms of its stability?’.

Two types of deformation

In buildings, almost all cases are due to two types of deformation:

• Angular distortion: the difference in settlement between two points of the foundation divided by the distance between them. It appears when the ground gives way unevenly and is responsible for the typical diagonal cracks in walls and partitions.
• Deflection: the downward movement of beams and floor slabs as they bend under load.

What the Technical Building Code says… and what it doesn’t

The Spanish Technical Building Code (CTE) limits these deformations for the serviceability limit state: the values beyond which damage appears that affects appearance, user comfort or the operation of equipment and installations. For example, for the angular distortion of the foundation:

For the deflection of beams and floor slabs, the CTE and the Structural Code (which replaced the former EHE-08 concrete standard) also set allowable values, intended to prevent damage to partitions, floor finishes and other non-structural elements.

What no standard sets is the value beyond which the stability of the foundation or the structure is compromised, which is precisely the condition for the decennial guarantee. Exceeding a serviceability limit does not mean that the damage falls under the decennial guarantee, and not exceeding it does not rule this out either.

How it is determined

Answering that question requires a technical study. Our structural damage assessment protocol has two phases:

1. Measurement of the actual deformations on site by means of a topographic levelling survey, supported by non-destructive tests.
2. Office analysis of the stresses that these deformations cause in the foundation and the structure.

Based on our experience, we have determined the range of deformation values that affects the stability of the structure. With it, we define the extent of the damage, whether it is structural and, therefore, what cover and liabilities may apply.

What to do if damage appears

1. Document it: dated photographs and a description of where it is and how it is developing.
2. Monitor whether it progresses, without covering it up or repairing it before the diagnosis.
3. Notify the developer in writing and, if you know who it is, the decennial insurance provider.
4. Bear the time limits in mind: the right to claim expires two years after the damage occurs.
5. Ask for an independent technical report to determine the cause and whether the damage is structural.

Important. This guide is for general information only and is no substitute for legal advice or a technical study of each case.