Engineered Timber I-Joists
I-joists, also known as engineered wood I-beams, are high-performance framing components used in flooring and roofing systems. Named for their distinctive “I” shape, these joists offer superior strength, stability, and design flexibility compared to traditional solid-sawn lumber. Acorn Timber Engineering manufacture and supply these engineered timber I-joists for construction projects across the UK.
James Jones JJI-Joists
I-Joist Suppliers
At Acorn Timber Engineering, we supply the James Jones JJI-Joist system, which is selected for its outstanding engineering credentials and environmental certifications. The system features:
- Powerful JJI Design software for tailored solutions
- PEFC certification for responsible timber sourcing
- PAS 2050 accreditation, offering project-specific carbon reporting and full chain-of-custody transparency
This means every project benefits from precision engineering, sustainable practices, and measurable environmental performance.
Our Speciality
Engineered For Strength And Efficiency
Each James Jones JJI-joist consists of two main parts:
- Flanges (top and bottom): Made from solid timber for strength and rigidity.
- Web (middle section): Made of oriented strand board (OSB), the web resists shear forces and ties the flanges together.
This design enables I-joists to carry heavy loads over long spans with minimal deflection, making them ideal for open-concept floor plans and wide roof designs.
Minimising Floor Squeaks
Why Builders Choose I-Joists
There are several reasons why builders choose I-Joists:
- Longer spans with fewer supports needed
- Lightweight and easy to handle
- Excellent Dimensional stability, no warping, shrinking, or twisting
- Consistent factory-controlled quality
- Reduced material waste and improved sustainability
I-joists help minimise floor squeaks, maintain ceiling flatness, and speed up installation, making them a smart choice for both residential and commercial builds.
Ensuring Performance & Safety
Installation Best Practices
To ensure performance and safety, I-joists must be installed correctly:
- Never drill or notch without following manufacturer guidelines
- Pay special attention to hole placement in the web
- Protect joists from prolonged moisture exposure
Do you need a solid, reliable solution for your next project? Contact the Acorn Timber Engineering design team today using the button below for expert advice, custom solutions, and a free quote.
