Lab
OFR Consultants
About the lab
OFR Consultants are one of the leading specialist fire engineering consultancies in the UK. A significant proportion of the OFR Consultants team have a background in research through their formal education and previous professional experience. We recognise the value of being involved in research to maintain our position at the forefront of fire engineering practice and innovation. Our development and sharing of knowledge involves in-house projects and the application of research to projects, often through collaboration with other industry, public and academic organisations.
Featured projects (1)
The Structural Timber Association Special Interest Group has been formed to address challenges in the sector, through a series of work packages to provide both guidance and evidence to support the fire safe design of mass timber High Rise Residential Buildings (HRRB) and commercial buildings.
Cross Laminated Timer (CLT) is increasingly adopted as a structural framing solution due to its sustainability benefits and impact on reducing construction programme. CLT is formed of a series of timber lamellae arranged orthogonally to give improved homogenous stiffness and stability. As an engineered timber product in residential applications, it is common to have all apartment and/or room bounding surfaces formed as CLT, i.e. the CLT not only forms elements of structure, but also serves a separating function.
In most instances in residential applications, the CLT is lined in some manner, plasterboard for example. For commercial projects, the scale of the fire enclosure is much larger, with the CLT generally only forming an exposed ceiling / slab structure.
For HRRB and similar types of purpose groups, the Building (Amendment) Regulations 2018 set out new statutory requirements in respect of the materials forming external walls and specified attachments which have been taken into account with this research.
The programme of fire performance experiments has been undertaken by leading CLT manufacturers including Binderholz, B&K Structures, Eurban, Henkel, KLH, OFR and Stora Enso, to provide test based evidence of behaviour which will enable specifiers and the market in general use CLT in the knowledge it is a safe building material.
Featured research (29)
The hydraulic model calculates the flow through a door constriction for a unidirectional flow of people primarily based on physical constraints. The method requires the physical door opening width to be reduced by a boundary layer adjustment to determine the effective width. However, the hydraulic model does not provide any guidance on what the flow might be when there is a counterflow condition. One option might be to simply represent counterflow with an equivalent half-door opening effective width. This paper compares the results from two agent-based, computational evacuation tools (Pathfinder and Evacuationz) to assess counterflow against the hydraulic model and data collected from people movement trials. The trials consisted of around 90 people travelling through an open doorway to generate unidirectional and counterflow scenarios. The trials also investigated how group identity might affect the counterflow measurements by gathering data when such identity was present or absent. Results suggest that the flow through the doorway in a given direction under counterflow conditions is greater than assuming half of the unidirectional flow. There appears to be an effect when in-group psychological behaviour is introduced such that the flow can show an overall increase when compared to having random groups. However, should participants interact then the in-group counterflow also exhibits a greater variability.
This paper provides understanding of the fire performance of exposed cross-laminated-timber (CLT) in large enclosures. An office-type configuration has been represented by a 3.75 by 7.6 by 2.4 m high enclosure constructed of non-combustible blockwork walls, with a large opening on one long face. Three experiments are described in which propane-fuelled burners created a line fire that impinged on different ceiling types. The first experiment had a non-combustible ceiling lining in which the burners were set to provide flames that extended approximately halfway along the underside of the ceiling. Two further experiments used exposed 160 mm thick (40-20-40-20-40 mm) loaded CLT panels with a standard polyurethane adhesive between lamella in one experiment and a modified polyurethane adhesive in the other. Measurements included radiative heat flux to the ceiling and the floor, temperatures within the depth of the CLT and the mass loss of the panels. Results show the initial peak rate of heat release with the exposed CLT was up to three times greater when compared with the non-combustible lining. As char formed, this stabilised at approximately one and a half times that of the non-combustible lining. Premature char fall-off (due to bond-line failure) was observed close to the burners in the CLT using standard polyurethane adhesive. However , both exposed CLT ceiling experiments underwent auto-extinction of flaming combustion once the burners were switched off.
Mass timber in the form of cross-laminated timber (CLT) panels has become a popular design option for the construction of buildings across the UK. However, there is currently concern amongst designers and approval bodies that the performance of CLT panels from different suppliers varies sufficiently such that each design necessitates specific consideration of the source of the CLT, with the underpinning fire strategy only holding where the mass timber elements are procured from a specific supplier. To assess whether such concerns are founded, this paper compares the in-depth temperature profiles, the mass loss rate, and charring depths of CLT panels from three major CLT suppliers, in a vertical (wall) configuration. The experimental campaign studied four different variables: (1) the effect of the lamella thickness, (2) the difference exhibited when using a polyurethane non-heat resistant adhesive or a modified polyurethane heat resistant adhesive, (3) the influence of having non-edge-glued joints of the laminations within the first lamella vs edge-glued, and (4) the CLT supplier. The samples were exposed to an incident heat flux of 50 kW/m 2 for 60 min using a radiant panel. The results indicate that the performance of the samples from the suppliers does not show a statistically significant difference for the same combination of parameters (adhesive type, lamella thickness and edge-glue). Thus, subject to parameters being consistent, i.e., adhesive, edge-gluing condition and lay-up, CLT can be specified in a generalised manner, improving confidence in the performance of the products and easing their procurement.
Concerns about the environmental impact of building construction is leading to timber being more commonly used. However, it often faces scepticism regarding its safety in the event of fire. This article provides a point of reference on the fire performance of cross-laminated timber through a review of large-scale tests. Although adequately protecting CLT can make its contribution to fire insignificant, some of the internal surface of an enclosure can be exposed whilst still achieving adequate fire performance. Natural fire tests show that the charring rate and zero-strength layer
thickness are higher than commonly used in guidance documents. The type of adhesive used to bond lamellae influences performance where delamination can lead to secondary flashovers, particularly in smaller enclosures. Structural elements can potentially collapse without self-extinction and/or suppression intervention. Tests to date have focussed on a residential context and knowledge gaps remain regarding larger enclosures, such as office-type buildings.
From the International Fire Professional Journal: This short scoping study produced by Charlie Hopkin, Danny Hopkin and Michael Spearpoint from OFR Consultants in Manchester, UK, explores different methods in which safety factors can be incorporated into fire engineering assessments and the indicative implications for the achieved safety level.
