What the DB-HR requires
The requirements are organised on four fronts. Airborne sound insulation between different occupancy units, against plant and activity rooms, and against exterior noise, with levels depending on the noise index of the area. Impact sound insulation, that of footsteps and dragging, governed by floor slabs and their floating floors. Limitation of reverberation in certain rooms, such as classrooms and dining halls. And limitation of the noise of the building's own services.
To verify compliance, the document offers two routes. The simplified option applies tabulated solutions that guarantee performance if executed under their conditions. The general option calculates the expected insulation from the elements and their junctions, normally with the document's official calculation tool. The simplified route dominates in ordinary residential; the general one prevails in singular projects or when optimisation is sought.
From requirement to construction solution
Acoustic compliance is played out on a well-known repertoire of solutions: separating partitions of two leaves or masonry with linings, perimeter resilient strips that decouple elements, floating floors on impact-damping layers, suspended ceilings where relevant, and silencers and resilient supports on the services. The article on acoustic insulation solutions walks through this repertoire with its performance and cost ranges.
The particularity of the acoustic package is that execution weighs as much as design. An interrupted resilient strip, a skirting board bridging the floating floor or a chase perforating a partition leaf degrades performance that the design calculated correctly. This is why demanding projects incorporate specific execution control and, increasingly, on-site acoustic measurements at completion.
| Acoustic front | What is required | Where it is decided |
|---|---|---|
| Between rooms | Airborne and impact sound insulation between dwellings and common areas | Choice of partition and treatment of its flanks |
| Against the exterior | Façade insulation according to the site's noise index | Joinery and façade build-up, from the municipal noise map |
| Building services | Noise and vibration limits for equipment and pipework | Position of plant rooms, from preliminary design |
| Reverberation | Reverberation time in the rooms the document defines | Finishes and volume of the common spaces |
Where it hits the budget
The regulatory cost of the DB-HR concentrates in partitions, floor slabs and finishes. As an indicative order of magnitude, the specifically acoustic items, membranes, strips, linings and floating floors, usually sit between 1 and 3 % of the PEM (presupuesto de ejecución material, the direct construction cost) in multi-family residential. It is a modest block in percentage terms and a highly profitable one in perceived quality, which explains why much mid and upper-range development designs above the regulatory minimum.
A fine economic reading requires separating two things: the cost of complying, which is that of the ordinary tabulated solutions, and the cost of repairing a non-compliance, which multiplies the former because it forces intervention on finished dwellings. Few budget items show such a marked asymmetry between doing it right the first time and correcting it afterwards.
Application errors worth avoiding
The first is entrusting performance to the star material while neglecting the flanks: sound goes around the partition through the elements framing it, and a tabulated solution only counts when executed in full. Junctions with slab, façade and partitions are detailed one by one.
The second is forgetting plant rooms: lifts, pressure groups and machine rooms have their own requirements that condition their position in the building from preliminary design. Their position is decided on the plan, while it is still free.
The third is ignoring the site's exterior noise: the level required of the façade depends on the area's noise, and joinery chosen without that data can fall short. The data comes from the municipal noise map before the joinery is chosen.
The fourth is measuring compliance only on paper: the distance between the drawings and the finished building is, in acoustics, the widest in the whole CTE, and only execution control narrows it. Execution control is programmed from the start of the works.
Note: percentages and orders of magnitude are indicative and vary with building type, region and market conditions. The reference in force is the consolidated version of the DB-HR published on the official CTE portal.