Timber I-joists
Timber I-joists: timber flanges and an OSB web – build-up, common depths and lengths, design according to ETA, uses in floors and walls.
German: Stegträger
A beam with an I-shaped cross-section, consisting of two timber flanges and a thin board web. The material is where it works hardest – in the flanges – so the beam is light but has a high load-bearing capacity.
How is it made?
The flanges are made of strength-graded timber, glulam or LVL, the web of OSB or hardboard. The web is glued into a groove in the flanges. Each product is manufactured on the basis of a European Technical Assessment (ETA).
Technical data
- Build-up
- two timber flanges and a thin board web, glued together
- Raw material
- flanges: strength-graded timber, glulam or LVL; web: OSB or hardboard
- Strength
- per product, according to the European Technical Assessment (ETA)
- Density
- depends on the materials of the flanges and web
- Adhesive
- structural adhesive (EN 301 or EN 15425)
- Common sizes
- depth 160–400 mm, length up to 16 m
- Standard
- ETAG 011 (based on ETA)
- What is it for?
- floor and roof joists, studs in highly insulated walls
Applications
- floor and roof joists
- studs in thickly insulated walls – the thin web reduces thermal bridging
- building services can easily be routed through the deep beam
What to watch out for
- The rules for web openings, bracing and connections are given in the ETA of the specific product – they must be followed in the design.
- The design is product-specific: the structural calculation is made with the data of the specific product.