Particular fire-related issues have to be addressed when building timber structures.
In a completed building, the timber structure will be protected by the internal lining and external cladding.
During construction however, the exposed timber structure might present a risk of fire.
Within the site, the contractor will put in place a fire safety plan to mitigate risks within the building and to the people on the site. This will be discussed between the design team members and the client under the CDM 2007 and will include areas such as fire safety coordinator, site safety plan, fire detection, escape routes, site accommodation, hot works, and smoking policy.
In addition, the risk that fire can spread to neighbouring structures both within or beyond the site boundaries if those structures are close to the site will also need to be considered.
The principle cause of fire spread from a timber frame structure to building is radiation.
Although there are no regulations to satisfy this risk, UKTFA has provided the construction industry with guidance on how to define the fire spread from the original timber structure to neighbouring sites for building floor area larger than 600m2.
The guidance provides safe separation distance for various type of timber frame (ranging from standard construction through to timber with flame retardant material and onto timber with non combustible material). This distance is calculated depending on the length of the building and the number of storeys considered.
While looking at this, the length of the building and storeys considered can be reduced by providing a full fire separation which then reduces the separation distance. In addition, fire treatment can be provided to the timber frame superstructure to reduce the separating distance.
While designing a timber structure, RISE will highlight any risks imposed onto the contractor by his design under the CDM regulations. In the case of the timber structure, RISE will discuss fire safety on site and strategy to avoid fire spread with the design team and the contractor.
Further information can obtained by reading the UKTFA “16 steps to fire strategy” and “Design guide to separating distances during construction” – both documents can be obtained by contacting RISE.