Image of a mixed use building with a wood facade

Firestop in wood construction

Solutions for direct installation – without mortar or formwork

Image of a firestop in wood test, after the material has been burned

Passive fire protection is key

Massive wood and especially cross-laminated timber (CLT) is increasingly used as a construction material for high-rise buildings as it has a high-load bearing capacity, high fire resistance and is light in weight.

It also burns slowly and in case of fire will never burn down completely because the charring of the wood acts as a natural fire barrier. However, this alone is not enough to help ensure occupants’ safety.

Photo with lots of complicated pipes configurations where building services pass through a wall

Importance of passive firestop

Passive fire protection is vital for creating a safer and code-compliant building. Compartmentation is a general safety requirement that applies to all buildings depending on their height and use class, regardless of their base material. The most common issue in a fire compartment is when building services need to pass through a separation floor or wall.

This requires adequate passive fire protection measures to seal the openings. During a fire, an important difference between concrete or drywall and wood is the combustibility of wood. Massive timber such as CLT chars at about 0.7 mm per minute. To fill the gap caused by the burning of the wood and to prevent the spread of smoke and fire, all openings in fire-rated walls and floors must be sealed with intumescent material.

3D rendering showing a comparison of a traditional mortar solution (on the left) and dry Hilti firestop blocks  in red (on the right) through a timber floor

Optimized construction process

So far, designing firestop solutions in wood is a difficult area in building regulations. In the absence of an approved solution for firestopping in timber, mortar has become the default choice today. This reduces productivity significantly, since installation and curing take time.

Our dry solutions, with the use of preformed products, can be directly installed in wood and exclude mortar. This means you can install firestop in pre-fabricated timber elements before they leave the factory – helping to reduce construction time on site by as much as half.

Compare a traditional solution with mortar (on the left) with a dry Hilti firestop solution (on the right).

Innovative solutions for demanding applications

Building services installations can be very complex which makes firestopping challenging. European and national testing institutes have certified Hilti firestop solutions in CLT and framed wood construction systems.

Preformed firestop devices are particularly suitable for timber constructions as they can be directly installed, help reduce installation risk and boost productivity.

Benefits include:

  • Fire rating up to 90 minutes (CLT and framed construction) 
  • Clean and quick installation 
  • Easy to inspect

Direct product installation without formwork

3D rendering of a cross-section of a wooded ceiling showing a CFS-SL Firestop sleeve and a CFS-CC Firestop cable collar around cables (electrical connections)

Electrical applications

Solutions for electrical cables and cable bundles:

CFS-SL GA Firestop speed sleeve CFS-CC Firestop cable collar
3D rendering of a cross-section of a wooded ceiling showing CFS-B Firestop bandages and a CFS-C EL Firestop endless collar around metal and plastic pipes (mechanical applications)

Mechanical applications

Solutions for wastewater, fresh water and heating pipes:

CFS-B Firestop bandage CP 648-E Firestop endless wrap strip
3D rendering of a cross-section of a wooded ceiling showing a CFS-BL P Firestop block around pipes,  cables and a cable tray (mixed penetrations)

Mixed penetrations

Solutions for large openings (pipes, cables and cable trays):

CFS-BL P Firestop block

Your firestop partner

Image of a firestop engineer carrying out a firestop text in laboratory conditions

Approvals for your applications

Based on sophisticated fire tests, our products have been approved for a broad range of firestop applications in wood.

European and national approvals of our firestop solutions from independent testing institutes, combined with our engineering judgements, make the planning and the construction processes easier and faster than ever.

Logos for ETA and CE approval, plus the Hilti Clean-Tec logo

Efficient and space-saving planning

The use of a compliant product range and system significantly increases efficiency during the planning process. The solutions have been tested with a minimum distance between the penetrations allowing for more usable space.

A rich library of technical drawings, containing all the key details that usually get buried in the approval texts, supports a quick design process.

Photo of a Hilti Engineer at his desk, carrying out an engineering judgement for a customer

Helpful engineering judgements

Wood is not a standardized base material like concrete. This makes each application different.

Although our approvals cover a wide range of applications, there can be project-specific needs that are not approved by international guidelines. In this case, our experts help by providing engineering judgements for project-based solutions covering the most demanding firestop applications.

Photo of pipes and cables in the ceiling being subjected to a firestop test in laboratory conditions

Testing with industry-leading manufacturers

We collaborate closely with international wood manufacturers to cover their unique wall and floor setups with fire tests. Our tailor-made tests support their customers by providing a firestop system for almost any penetration they need.

A Hilti engineer and account manager providing on-site support and consultation to a customer

On-site support and consultation

During the construction phase, either at the production plant or at the jobsite, our experienced engineers consult you on the installation process and help you tackle all challenges.

We help you to avoid unnecessary project delays and to choose the right solution.

I am really glad that with Hilti we will be able to work in full accordance with all project requirements in the future

Dr. Dirk Kruse
Fire protection engineer
DK Brandschutzingenieure GmbH

Project references

Architects impression of the Walden 48 timber multi-story building in Berlin, Germany


The challenge was to meet the high safety standards required when firestopping in wood. Every pipe and cable penetration in the fire-rated CLT walls had to be sealed with firestop products rated for 90 minutes. The solution offered by our experts was a custom proposal with an engineering judgement. Our firestop blocks CFS-BL P were specified to seal the large openings with mixed penetrations. (Architecture: ARGE Scharabi | Raupach, Berlin, Rendering: © Render-Manufaktur, Berlin)

Find out more about Walden 48
Architects impression Riedpark a four-story multi-family house in Lauchringen, Germany

Riedpark: a four-story multi-family house in Lauchringen, Germany

The 90-minute fire rating requirements of a building designed without gypsum board insulation had to be met. The non-standard configuration of the mechanical penetrations made the design of the right firestop solution even more challenging. Our solution was a joint fire test with the manufacturer Lignotrend. All mechanical and electrical penetrations were tested on their floor. For the mechanical applications, our CFS-C EL endless collar was used. Our CFS-BL P firestop blocks were selected to seal the large cable penetration openings. (Picture: Lignotrend / Foto&Design, Waldshut-Tiengen)

Find out more about Riedpark

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