Metal web joists have long been used in the UK construction industry and are continually growing in popularity with architects, specifiers, home builders and contractors.
They share the same basic elements as trussed rafters – timber structural members joined with pressed-steel nail plates to create a rigid supporting frame. Not surprisingly then, many of the UK’s manufacturers of metal web joists are also trussed rafter manufacturers. This can save money and help streamline the supply chain for the end customer.
With the increasing specification of mechanical ventilation and heat recovery (MVHR) systems and smart home systems adding to the services occupying the floor zone, metal web joists look set to continue growing in popularity for many years to come.
- Easier installation of services such as wiring, plumbing, cabling, heating pipes etc. resulting in the reduction or elimination of surface pipework
- No need to cut or drill holes in the joist
- Increased spans, simpler installation of utilities, flexibility in design and faster erection can result in significantly reduced building costs
- The depth, length and specification can all be adjusted to produce joists with specific performance criteria that can span greater distances than solid timber joists
- The use of smaller timber sections together with the metal webs means that there is less shrinkage and a reduced risk of squeaky floors
- As metal web joists are made to measure, site wastage is virtually eliminated
- Some types of metal web joist also have a solid timber ‘trimmable end’ to allow for any on-site discrepancies
- The open web structure means they are lighter to handle than solid timber joists
- Metal web joists can eliminate the need for loadbearing intermediate walls, giving the architect greater design freedom and flexibility
- The wide timber chords make for easier fixing of flooring and ceiling and there is no need for herringbone strutting
- Metal web joists when used with a rigid strongback reduce floor vibration