One question that often arises when homeowners are planning an extension with timber cladding is whether the cladding needs to be fire rated.
There is no single answer that applies to every extension. The requirements will depend on the particular building, its location, the proposed wall construction, and the regulations and approvals applying to the project.
It is therefore important to consider fire performance early in the design process, before the cladding is specified, priced or ordered.
When might fire-treated cladding be needed?
Whether fire-retardant-treated timber cladding is required must be assessed for the individual project. Relevant considerations may include the building’s design and use, its relationship with its surroundings, the construction of its external walls, and any requirements identified through the planning and building control processes.
The project’s architect or another suitably competent professional should establish the applicable requirements and discuss the proposed construction with the appointed building control body.
Where a particular reaction-to-fire performance is required, the project team will need to select a suitable product supported by appropriate test and classification evidence. That evidence should relate to the product’s proposed use and be reviewed before the cladding is specified or purchased.
Considering fire performance during the design process
Fire performance is best considered during the early design stages, while the external appearance and wall construction are still being developed.
Addressing it early gives the architect or designer time to:
- Establish the requirements applying to the project.
- Identify potentially suitable cladding products.
- Obtain and review the relevant technical documentation.
- Coordinate the cladding with the proposed wall construction.
- Discuss the design with the appointed building control body.
Leaving these questions until procurement or construction could result in changes to the specification, additional costs or delays while alternative products and supporting evidence are obtained.
It is also important not to treat a reaction-to-fire classification as a general approval covering every possible use of a product. Evidence obtained for one product or installation should not automatically be assumed to apply to a different timber species, profile, thickness, substrate, fixing arrangement or wall construction.
The project designer should review the available evidence and determine whether it is relevant to the proposed application.
Fire-retardant-treated timber cladding
Timber Cladding Specialists, a UK timber cladding supplier, offers a specialist fire rated cladding treatment service UK. The company states that it can provide factory-treated timber cladding achieving Euroclass B-s1,d0 in accordance with BS EN 13501-1.
According to the supplier, treatment is available for a range of timber cladding options, including:
- ThermoWood
- Siberian larch
- Nordic spruce
- Douglas fir
The supplier also states that classification documentation and installation guidance can be provided for consideration by the project’s architect, designer and appointed building control body.
The availability and suitability of a particular treatment or classification should be confirmed directly with the supplier for the exact timber species, profile, thickness, finish, installation method and intended use.
Relevant product documentation should be obtained and reviewed by a suitably competent professional before the material is specified or purchased.
Choosing a timber species
Different timber species offer different appearances, profiles, durability characteristics, maintenance requirements and price points.
Timber Cladding Specialists offers fire-retardant treatment for a selection of timber cladding products, including ThermoWood, Siberian larch and Nordic spruce. The supplier can provide information about the available options and technical documentation relating to the chosen product.
When selecting timber cladding, the project team should consider more than its initial appearance. Factors such as weathering, durability, coatings, maintenance and suitability for the intended external environment may also be relevant.
These matters should be checked for the particular product and project rather than assumed solely from the timber species.
Confirming the right solution
Before committing to a timber cladding product, homeowners and their design teams should:
- Obtain project-specific advice from a suitably competent professional.
- Establish any relevant planning and Building Regulations requirements.
- Discuss the proposed wall construction with the appointed building control body.
- Obtain the product’s current test and classification documentation.
- Confirm that the evidence is relevant to the proposed application.
- Check any installation, maintenance and environmental-use requirements with the supplier.
Early coordination between the homeowner, architect or designer, supplier and building control body can help identify an appropriate solution before products are ordered or construction begins.
For further information about its products and treatment services, see Timber Cladding Specialists’ do I need fire rated cladding on my extension UK guide.
Important information: This article provides general information and supplier-provided product details only. It does not constitute architectural, fire-safety, legal or Building Regulations advice. Requirements and product suitability must be assessed for each project by suitably competent professionals and discussed with the appointed building control body. Product specifications, classifications and supporting evidence should be obtained and verified directly with the manufacturer or supplier.
