Timber webbed I joists have many advantages over metal ones:
- Much less embodied energy in their construction
- We can pre-cut MVHR duct routes in them at the factory – this can’t be done with metal webbed ones, you just have to hope the metal ones are in the right place to allow a duct to be installed – which is especially difficult around floor openings such as around stairs.
- Our timber milling machine can cut the timber joists to length, useful around complex floors / around staircase openings. You can’t cut metal on a timber milling machine
- No cold bridging to external walls when joists go over walls to the outside face.
- The pre-cut duct holes in our joists support the ducts in a precise position, ensuring that there are no conflicts on site with other trades, such as between the ducts and the lighting. This can be pre-designed.
First-fix trades people like I beam walls, since there is minimal hole boring needed. In joists if cables are running perpendicular to joists then small holes can quickly be bored on site in the joists exactly where needed, but most first fix takes place in the walls where wires can run over the top of studs in the gap between the stud web and top plate web (see image).