Metsä Wood is launching Finnjoist FP+, a pre-insulated I-joist developed to help timber frame manufacturers and housebuilders build more efficiently and meet enhanced fire performance requirements set out in the Structural Timber Association Design guide to separating distances during construction, Product Paper 4.
This verified I-joist solution provides the timber frame sector with a tested and practical way to meet requirements, reduce production stages, and improve consistency, the company says. Finnjoist FP+ combines the established structural performance of the Finnjoist I-joist with insulation applied directly to the web. This removes the need for insulation to be measured, cut, and fitted separately in the factory.
The new solution has achieved an REI 30-minute fire rating and is included in the Structural Timber Association’s updated Product Paper 4 guidance. It also achieves 43dB acoustic performance for intermediate floors without additional insulation between the joists, exceeding the 40 dB standard in England and Wales and meeting Scotland’s higher 43dB standard.
Matt Linegar, Commercial Director Engineered Wood Products at Metsä Wood, said: “Finnjoist FP+ has been developed to solve a very practical challenge for timber frame manufacturers: how to deliver the required performance while reducing time, handling and additional production stages. By applying the insulation within our factory, we can offer customers a more consistent and ready-to-process solution, while retaining the proven structural benefits and design familiarity of Finnjoist.”
Finnjoist FP+ is supplied in full lengths for customers to cut to their required dimensions and can be integrated into established timber frame manufacturing processes using the existing Finnjoist structural data, span tables and design principles.
The product will initially be available in standard widths within the 240mm joist depth, with selected length options, and will launch in August 2026 on a made-to-order basis through Metsä Wood’s usual sales channels. Customers will be supported by Metsä Wood’s engineering and technical teams, established Finnjoist design resources and online portal. Product samples will also be available upon request.
