Specialist in Certified Passive Fire Protection: Total Risk Mitigation

Firestop seals explained WBDBO 🔥 & WRD 💨

WBDBO (EI/EIW) + WRD (Ra/R200, Sa/S200): the Dutch framework for fire and smoke resistant compartmentation in accordance with Bbl, NEN 6068 and NEN 6075.

This page is a technical explainer for design, construction and FM teams. Here you will find:

• key concepts around fire resistance (EI, WBDBO) and smoke resistance (WRD)
• the role of NEN 6068 and NEN 6075
• the link with European test standards (EN 1366 / EN 1634 / EN 13501-2)
• practical frameworks from ISSO-SBR 809
• an overview of the main standards and an FAQ

🔥 Fire seals in practice – our service

💨 WRD in practice – smoke-resistant seals

WRD – Smoke resistance in plain language

Fire is not the only problem – smoke is

Most people know fire resistance in minutes:

• EI 30
• EI 60
• EI 120

That indicates how long a wall, floor, door or penetration will resist fire and high temperature.

In real fires, smoke is often more dangerous than flames:

• Smoke spreads much faster than fire.
• Smoke fills corridors and stairwells very quickly.
• Most fatalities in building fires are due to smoke inhalation, not burns.

That is why, in the Netherlands, we do not stop at EI alone.

The Bbl (Besluit bouwwerken leefomgeving – Building Decree) also uses WRD:

WRD = Weerstand tegen RookDoorgang (resistance to smoke passage) → how well a separation stops smoke.

Fire safety in NL = EI + WRD Not EI alone.

What is WRD?

WRD indicates how well a wall, floor, ceiling or door set prevents smoke from leaking from one space to another.

NEN 6075 uses two levels:

• Ra – smoke tight at room temperature (around 20 °C)
• R200 – smoke tight at room temperature and at 200 °C

For individual components (such as a door, hatch or damper), European standards use:

• Sa – smoke control at ambient temperature (~20 °C)
• S200 – smoke control at 200 °C (plus ambient temperature)

You can think of it like this:

• Sa / S200 → how smoke-tight is this component?
• Ra / R200 → how smoke-tight is the entire separation (wall + door + penetrations + ducts + junctions)?

The separation only works properly if all components together keep the smoke where it belongs.

Where is WRD especially important?

WRD is especially important where people must be able to escape safely:

• Between sub-fire compartments (SBCs),
• for example apartments, hotel rooms, patient rooms.
• Between those SBCs and protected escape routes, such as:
• protected corridors

  - stairwells that form protected or extra protected escape routes.

In these locations, Dutch law says:

The separation must be smoke resistant, and WRD must be determined according to NEN 6075.

In these zones the rule is very simple: EI alone is not enough. You need EI and WRD.

Why “EI only” is not enough

A wall or door can be EI 60 and still allow a lot of smoke through:

• along the junction between door leaf and frame
• through cracks and gaps
• at poorly sealed penetrations and ducts

In short:

• EI tells you how long the separation resists fire and heat.
• WRD tells you how well the separation resists smoke.

For safe escape routes in Dutch buildings – especially in stairwells and escape corridors – you need both:

EI + WRD – not EI alone.

An EI certificate without WRD therefore does not cover the full legal requirement where the Bbl prescribes a smoke-resistant separation.

When is WRD (NEN 6075) mandatory in NL?

Core principles

Very briefly, it works like this:

• The Bbl defines the legal rules for buildings.
• For smoke separations, the Bbl refers to NEN 6075:2020 as the method to determine WRD.
• WRD is expressed as:
• Ra / R200 for the separation as a whole, and

  - uses Sa / S200 classes for components (doors, dampers, etc.) as input.

• WRD is about air/smoke leakage, not about fire load or temperature rise.

The usual European fire tests:

• EN 1366
• EN 1364
• EN 1365
• EN 1634-1

are about fire resistance (E / EI / EW) – not about WRD. They are input for EI / WBDBO, not for Ra / R200.

So:

• EI + NEN 6068 → how fire can spread between spaces (fire spread / flashover between compartments).
• NEN 6075 (WRD) → how smoke can spread between spaces.

Where both apply, both must be satisfied.

Everywhere the Bbl requires a smoke-resistant separation, WRD according to NEN 6075 is a legal requirement, not an optional extra.

New-build – sub-fire compartments (SBC)

For new-build, the Bbl requires that a sub-fire compartment (SBC):

• has a WRD value determined according to NEN 6075; and
• complies with a European smoke class Ra or R200.

WRD is then mandatory for separations:

• Between SBCs within the same fire compartment (BC).
• From an SBC to spaces with (extra) protected escape routes, for example a stairwell that forms a protected escape route.
• From an SBC to certain lift shafts and escape-related spaces where the Bbl imposes a smoke requirement.

Key concept:

• A fire compartment (BC) is the larger fire compartment (focus: WBDBO / NEN 6068).
• B sub-fire compartment (SBC) is a smaller protected zone within a BC (extra protection for people and escape – focus: WRD / NEN 6075).

As soon as a separation both:

• 1. forms the boundary of an SBC, and
• 2. is designated as smoke-resistant in the Bbl,

WRD according to NEN 6075 formally becomes mandatory.

Existing buildings

In existing buildings the WRD requirement does not disappear. The Bbl sets a minimum level, for example:

• WRD from an SBC to an enclosed space within the same fire compartment must be at least 20 minutes, determined according to NEN 6075 (art. 3.46 Bbl).

Technically, this often comes down to at least a separation that behaves as Ra, and in more critical situations effectively as R200.

In renovation or refurbishment projects – for example where a dwelling opens onto a corridor with a protected escape route – the required WRD may again move towards R200.

Rule of thumb:

If a separation has a smoke separation function for escape, WRD according to NEN 6075 is mandatory – often Ra / “20 minutes”, and in more demanding situations R200.

Stairwells and escape routes

A stairwell is usually part of the escape route and is often:

• a protected escape route, or
• an extra protected escape route.

Consequences:

The separations between spaces / SBCs and the stairwell must then comply with both:

• fire resistance: EI / WBDBO, and
• smoke resistance: WRD, determined according to NEN 6075.

So:

If a stairwell is a protected escape route, all connecting walls and doors must comply with WRD – not just EI.

A simple “EI 60 door” is, in that context, legally and technically insufficient.

BC ↔ BC and WRD

Between fire compartments (BC ↔ BC) the main requirement is WBDBO, checked via NEN 6068.

WRD according to NEN 6075 only becomes mandatory if that same separation also:

* forms the boundary of a sub-fire compartment (SBC), and/or

• forms the separation towards an (extra) protected escape route where the Bbl imposes a smoke requirement.

Examples:

• Two industrial halls next to each other, each a BC, without a protected escape route in the separating wall → usually WBDBO only, no explicit WRD requirement.
• Two apartments next to each other, which are also (protected) SBCs with escape relevance → WBDBO + WRD (often R200) both apply to the same wall.

ISSO-SBR 809 in practice

ISSO publication 809 – Fire-safe penetrations:

• has been updated for NEN 6075 + Bbl
• provides practical guidelines for the design and execution of fire and smoke resistant penetrations, so that:
• EI is maintained, and

  - the WRD (Ra / R200) of the separation is not compromised by penetrations, ducts and installations.

In one sentence:

• Legally: Bbl + NEN 6075 make WRD mandatory wherever a smoke-resistant separation is prescribed.
• Practically: ISSO-SBR 809 shows how to realise EI + WRD in the details (penetrations, ducts, installations).

Why EI-only is legally insufficient where WRD is required

What EI does and does not cover

EI from EN tests (EN 1366 / EN 1634-1 / EN 1364 / EN 1365) describes fire resistance:

• E – Integrity: no flames / openings.
• I – Insulation: temperature on the cold side remains below threshold values.

These tests result in E / EI / EW classifications (via EN 13501-2).

They do not provide:

• a Ra / R200 classification, or
• an Sa / S200 smoke class (except where EN 1634-3 is specifically used for smoke on a component).

EI does not measure:

• how much smoke leaks via joints, doors, gaps or penetrations,
• especially not at cold smoke (~20 °C).

By contrast, WRD according to NEN 6075:

• explicitly looks at air/smoke leakage between spaces, and
• classifies the separation as Ra or R200 based on allowable leakage.

Result:

A wall, door or penetration can be perfectly EI 60 and still behave like a smoke sieve.

In that case it fails WRD – and does not comply with the Bbl requirement for a smoke separation.

Components vs separation: Sa / S200 vs Ra / R200

NEN 6075 makes a clear distinction:

• Ra / R200 → performance of the entire separation (wall + door + penetrations + ducts + junctions).
• Sa / S200 → performance of individual components, for example:
• door sets and hatches tested according to EN 1634-3

  - fire and smoke dampers - in some cases specific penetration systems with declared leakage behaviour.

To comply with the legal WRD requirement, you must:

• 1. demonstrate that the separation as a whole achieves the required Ra or R200 according to NEN 6075, and
• 2. use components with appropriate Sa / S200 substantiation, so that their leakage does not push the total separation above the Ra/R200 leakage limit.

EI-only test reports say nothing about this and do not prove WRD.

The essence in short

Putting it all together:

• 1. the Bbl explicitly requires WRD (Ra / R200) via NEN 6075 between certain spaces (SBCs, protected escape routes, certain shafts)
• 2. NEN 6075 is leakage-based; you cannot derive WRD from EI alone
• 3. ISSO-SBR 809 is written to ensure that penetrations, ducts and installations respect both EI and WRD

Therefore:

In every Dutch situation where the Bbl requires a smoke-resistant separation, a solution with EI alone is objectively and legally inadequate.

You must also demonstrate WRD according to NEN 6075, usually by:

• using components with appropriate Sa / S200 class (e.g. EN 1634-3 tested doors, smoke control dampers), and
• demonstrating that the entire separation complies with Ra / R200, including all penetrations and junctions.

R vs S – the notation at a glance

To keep it clear:

• S (Sa / S200)
• relates to components (door set, hatch, damper, etc.)

  - Sa = smoke control at ambient temperature (~20 °C) - S200 = smoke control at 200 °C (and ambient temperature)

• R (Ra / R200)
• relates to the entire separation / smoke route (wall + door + penetrations + ducts)

  - Ra = smoke-tight separation at ambient temperature (~20 °C) - R200 = smoke-tight separation at ambient temperature and 200 °C - this R = rook (smoke) at separation level – not the R for load-bearing capacity from EN 13501-2

• “20 minutes WRD”
• older / minimal form still found in parts of the Bbl for existing buildings

  - in the modern system this is essentially translated into a requirement for Ra / R200 based on leakage, not just time

What each standard does and does not give you (short)

Legend (short):

• EI / EW / R → Fire resistance only (no smoke class).
• Sa / S200 → Smoke performance of components.
• Ra / R200 → Smoke performance of the complete separation, as defined in NEN 6075.

Do you want to know whether your design or building complies with Dutch WRD requirements? Contact BraVeBo B.V. for an EI + WRD compliance check.

🔒 Request EI 🔥 + WRD 💨 compliance check

Demonstrable compliance: the core standards

Compliance: a legal and insurance necessity

In the Netherlands and the EU, effective fire sealing is a legal requirement under the Besluit bouwwerken leefomgeving (Bbl). Under CPR (EU 305/2011), products that fall under a harmonised standard or are assessed via ETA (EAD/ETAG 026 route) must be provided with a Declaration of Performance (DoP) and CE marking.

In addition, building owners and users/managers have an ongoing legal responsibility to maintain all fire safety provisions. This includes continuously safeguarding the integrity of certified fire seals and fire compartments – a mandatory condition for the operating permit.

• Mandatory compliance: complying with the Bbl and relevant NEN standards is required for building and use permits
• Insurance validity: after a fire, claims can be rejected if non-compliant or substandard fire seals contributed to fire or smoke spread
• Specific duty of care: the Bbl imposes a duty of care on both the building owner and the user/manager to prevent hazardous situations and maintain fire safety provisions; designate a responsible person within FM/governance for this

Traceability: your audited proof of safety

We provide documented, audited proof of safety. Our focus on traceability creates trust and limits liability.

What we guarantee:

• Unique identification: QR/ID per seal, linked to work order and drawing.
• Penetration data: type (cable, cable tray, pipe/duct), diameter/dimensions, residual openings.
• Full documentation: photo log before–during–after, exact location (room/coordinates), materials with batch/lot and DoP/CE.
• Classified solution: brand/type, ETA/EAD (ETAG 026) reference, EI classification, WRD Sa/S200 in accordance with NEN 6075 / EN 13501-2 / EN 1366-3/-4 / ISSO-SBR 809.
• Audit & archiving: complete dossier (PDF/ZIP), 10-year retention in Fire Seal DB, version control and role-based access.

Your benefit: faster inspections, audits and insurance claims, direct traceability for re-entry, and a stronger legal position.

Standards & regulations – overview

EN 1366 — fire resistance tests (series)

• EN 1366-1 — Ventilation ducts

  Fire test method for ventilation ducts in separating constructions.

• EN 1366-2 — Fire dampers

  Fire tests for dampers between compartments.

• EN 1366-3 — Penetrations

  Fire resistance test for cables, pipes and cable trays.

• EN 1366-4 — Linear joints

  Fire tests for joints in walls and floors.

• EN 1366-5 — Service ducts and shafts

  Fire tests for ducts and shafts.

• EN 1366-6 — Raised floors and hollow floors

  Fire tests for raised floors and hollow core systems.

• EN 1366-7 — Conveyor systems and closures

  Fire tests for conveyor systems and closures.

• EN 1366-8 — Multi-compartment smoke extraction ducts

  Fire tests for smoke extraction ducts crossing multiple compartments.

• EN 1366-9 — Single-compartment smoke extraction ducts

  Fire tests for ducts within a single compartment.

• EN 1366-10 — Smoke control dampers

  Fire tests for smoke control dampers.

• EN 1366-11 — Cable systems and components

  Fire tests for protection of cable systems and components.

• EN 1366-12 — Non-mechanical fire barriers

  Fire tests for non-mechanical fire barriers.

• EN 1366-13 — Chimneys

  Fire tests for chimneys.

EN 1634 — doors & shutters

• EN 1634-1 — Fire resistance (doors/shutters)

  Fire tests for fire resistance of doors and shutters.

• EN 1634-2 — Hardware characterisation

  Tests for hardware contributing to the performance of doors and shutters.

• EN 1634-3 — Smoke control (doors/assemblies)

  Smoke control tests for doors and shutters; relevant for Sa/S200.

Classification & Dutch frameworks

• EN 13501-1 — Reaction to fire

  Classification of products by reaction to fire.

• EN 13501-2 — Fire resistance of building elements

  Classification of building elements by fire resistance (EI/W, etc.).

• NEN 6068 — WBDBO (Bbl)

  Weerstand tegen BrandDoorslag en BrandOverslag (resistance to fire spread between compartments) — mandatory under the Bbl.

• NEN 6069 — Determination of fire resistance

  Dutch method for determining fire resistance.

• NEN 6075 — Smoke leakage (Sa/S200)

  Assessment of WRD — resistance to smoke passage for cold smoke (Sa) and smoke at 200 °C (S200).

Smoke and heat control systems

• EN 12101-7 — duct sections in smoke and heat control systems
• EN 12101-8 — smoke control dampers

Practical guidelines & competencies

• ISSO-SBR 809 — guideline for firestop penetrations
• NEN 3140 — electrical safety in low-voltage installations (relevant for technical rooms and IT zones)

Frequently asked questions (WBDBO/WRD)

What is WBDBO?

WBDBO stands for Weerstand tegen BrandDoorslag en BrandOverslag – the resistance of a construction against fire spread and flashover between compartments. In the Netherlands this is assessed according to NEN 6068.

What is WRD (Sa / S200)?

WRD means Weerstand tegen RookDoorgang – the resistance of a construction against smoke passage, according to NEN 6075.

• Sa = smoke control at ambient temperature
• S200 = smoke control at 200 °C

These classes are used for components (e.g. doors tested according to EN 1634-3) and form input for the Ra/R200 assessment.

Which tests apply to penetrations and joints?

• EN 1366-3 applies to penetrations
• EN 1366-4 to linear joints

Classification is done according to EN 13501-2.

Do you provide audit-ready documentation with QR traceability?

Yes. Every seal receives a unique QR code and label. We record photo logs, position, material batch and provide a complete dossier ready for audits, inspections and insurance queries.

Which penetrations and openings do you treat?

Cable bundles, metallic and plastic pipes, ventilation/smoke ducts, linear joints and irregular openings. We select the tested system based on geometry, required classification, movement and environment.

How does BraVeBo ensure compliance in high-security environments?

We use authorised systems (such as Firetect), work in accordance with the relevant EN 1366 series and ISSO-SBR 809, and follow site-specific procedures. Planning, access and handover are aligned with the critical processes of the site.

Do you want to know whether your design or building complies with Dutch EI + WRD requirements?

🔒 Request EI 🔥 + WRD 💨 compliance check