Screed and insulation in Brussels: specificities of Brussels buildings

Renovating or building in Brussels imposes very specific constraints. Between mansions, Art Nouveau buildings, limited ceiling heights and regional PEB requirements, the choice of screed and floor insulation must adapt to the urban context of Brussels. In this article, we review the technical, regulatory and practical specificities of screed and insulation projects in the Belgian capital.

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The architectural specificities of Brussels buildings

Mansions and ancient buildings

Brussels has an important architectural heritage, with numerous 19th century mansions and buildings built between 1880 and 1930. These buildings have particular characteristics that influence the choice of screed and insulation:

• Wooden floors : many of these buildings have retained their original floors on wooden joists. Installing a heavy traditional screed is often impossible without structural reinforcement.
• Generous ceiling heights : unlike modern buildings, rooms often offer 3 to 3.5 meters in height, which leaves more room for insulation and screed.
• Existing uneven slabs : in cellars and ground floors, the slabs may be irregular, cracked or non-existent (clay in some old cellars).

👉 Adapted solution : in these cases, a lightweight screed or a solution of dry screed may be preferred to limit the load on the structure.

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Apartment buildings and condominiums

Brussels apartment buildings pose other challenges:

• Compulsory acoustic insulation between floors : comfort standards and condominium rules require effective sound insulation.
• Reduced spaces in studios and small apartments : every centimeter counts, which makes fine and efficient insulation solutions indispensable.
• Coordination with the trustee and the other co-owners : screed work may require the agreement of the general meeting, especially in the event of changes in ground loads.

👉 Adapted solution : one floating screed with acoustic insulation (Insulit Bi+9 type) makes it possible to drastically reduce impact noise while respecting thickness constraints.

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Major constraint in Brussels: the height available

Why is ceiling height an issue?

In renovations in Brussels, especially in recent buildings or conversions of offices into housing, the height available on the ground is often limited. Adding thermal insulation and a screed can cause a loss of between 8 and 15 cm in height, which can be a problem for:

• The height of existing doors
• The connection with the other rooms
• Compliance with the regulatory minimum height (2.30 m for a stay)

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Solutions adapted to low heights

1. Projected PUR insulation (2 to 5 cm)

Polyurethane foam offers the best thermal performance for a minimum thickness. With only 3 cm of PUR + 5 cm of screed, you get efficient insulation while limiting the height to 8 cm.

2. Anhydrite fluid screed (3 cm minimum)

Anhydrite screed allows you to install a screed only 3 cm thick above a heated floor, compared to 5 to 7 cm for a traditional screed. This is a valuable gain in constrained projects.

3. Fine acoustic underlays

For sound insulation, solutions such as Plastifoam (4+2 mm) Or theEthafoam (5 mm) allow impact noise to be reduced without taking up space.

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The specific PEB requirements in Brussels

What are the Brussels PEB regulations?

La Energy Performance of Buildings (PEB) imposes strict standards in the Brussels-Capital Region:

• New construction : since 2015, all new construction must reach a very low level of energy consumption (BEN - Neutral Energy Building from 2025).
• Heavy renovation : as soon as a project involves more than 75% of the building's surface, EPB requirements apply.

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Floor insulation and EPB: what you need to know

To meet the EPB requirements, theground floor insulation on the ground floor is essential. The regulation imposes a maximum U value :

• New construction : U ≤ 0.24 W/m²K
• Renovation : U ≤ 0.30 W/m²K (depending on the year of construction)

👉 This means that a simple screed without insulation is no longer enough. It is imperative to integrate a insulating layer (PUR or EPS) to achieve these performances.

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How do you achieve these performances?

SolutionThickness requiredU value obtainedProjected PUR (λ = 0.025)10 cm0.25 W/m²KEPS in mortar (λ = 0.038)15 cm0.25 W/m²Kprojected PUR (λ = 0.025)8 cm 0.31 W/m²K (renovation)

Davide Chape Council : under new construction in Brussels, we recommend 10 cm of projected PUR under the screed to ensure compliance with EPB standards without compromising on performance.

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Grants and subsidies in Brussels for floor insulation

Prime Renolution (ex-Prime Energy)

The Brussels-Capital Region offers Renolution bonuses to encourage thermal insulation, including floors.

Indicative amounts for floor insulation (according to income and category):

• Category I (high incomes) : €30/m²
• Category II (average earnings) : €50/m²
• Category III (modest incomes) : €70/m²

Conditions :

• Insulation of at least 15 m²
• Minimum R value (thermal resistance) of 3.5 m²K/W
• Invoice issued by an approved contractor
• Work carried out after the award of the grant

👉 example : for 50 m² of PUR insulation under screed (category II), you can recover up to €2,500.

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Brussels green loan

The green loan at a reduced rate (0.5% to 2%) can finance insulation work up to €25,000 without mortgage collateral. An attractive option for homeowners who are renovating.

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Characteristics of construction sites in Brussels

Difficult access and urban logistics

Brussels imposes logistical constraints that are not found in rural areas:

• Narrow streets in the old districts (Sablon, Marolles, Saint-Gilles): difficult to park a mixer truck.
• Low Emission Zones (LEZ) : trucks must comply with Euro standards to drive in Brussels.
• Temporary parking permit sometimes necessary to occupy a parking space during the construction site.

Chez Davide Chape, we manage these constraints by:

• Planning access with the customer in advance
• Using LEZ compliant trucks
• Optimizing parking time (most of our projects are completed in 1 to 2 days)

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Coordination with other trades

Brussels projects often involve several stakeholders (architect, general contractor, electrician, heating engineer). Good coordination is essential for:

• Integrate the underfloor heating before installing the screed
• Respect the overall renovation schedule
• Avoid costly back and forth

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Acoustic insulation: a major challenge in urban areas

Why is sound insulation crucial in Brussels?

Living in the city means proximity to neighbors, shops, transport. Noise pollution are one of the main sources of discomfort in Brussels housing.

One poor acoustic insulation between floors may result in:

• Neighborhood conflicts
• A loss in the value of the property
• Legal remedies (a tenant may require work if the standards are not respected)

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Acoustic standards in Belgium

The standard NBN S01-400-1 imposes acoustic insulation requirements between homes:

• Delta Lw ≥ 54 dB for impact noise between apartments
• To reach this level, a simple screed is not enough: you need a dedicated acoustic underlay.

👉 Answer: Davide Chape : with our underlay Insulit Bi+9 (Delta Lw of 30 dB on bare slab), combined with a 6 cm floating screed, you easily achieve the required performance.

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Practical case: renovation of an apartment in Ixelles

background

• 75 m² apartment in a 1920 building
• Existing concrete slab, uneven
• Ceiling height: 2.80 m
• Objective: thermal and acoustic comfort, floor heating, PEB compliance, renovation

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Solution implemented by Davide Chape

1. Preparation : cleaning and light levelling of the existing slab
2. Sound insulation : installation of Insulit Bi+9 (9 mm) over the entire surface
3. Thermal insulation : projection of 6 cm of PUR foam (final U value: 0.28 W/m²K)
4. Floor heating : installation of hydraulic hoses
5. Anhydrite fluid screed : pouring a 5 cm screed (3 cm above the pipes)

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Results

• Total height lost : 11 cm (acceptable with the initial height)
• Acoustic performance : Delta Lw > 30 dB → optimal comfort
• Thermal performance : PEB renovation compliant
• Duration of the work : 2 days
• Total cost : ~85 €/m² (screed + thermal insulation + acoustic insulation)
• Prime Renolution recovered : €2,250 (category II, €30/m² on 75 m²)

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Conclusion: adapting the solution to the Brussels context

Working in Brussels requires deal with the constraints of the existing building, regional regulatory requirements and the city's logistical challenges. Each project is unique and requires a tailor-made analysis :

• Old houses → lightweight screeds, attention to the structure
• Flats → priority acoustic insulation
• Low height available → PUR projected + fluid screed
• New construction → PEB compliance with a minimum of 10 cm of insulation

Chez Davide Chape, we know perfectly well the specificities of Brussels. From our base in Ternat, we operate daily throughout the Brussels-Capital Region. Our team masters access constraints, local PEB requirements and the expectations of architects and contractors working on urban projects.

Contact us now to get a quote.