- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 05 Apr 2018
Herringbone struts can be made of timber or pre-galvanised mild steel. They are sometimes used as an alternative to solid block bridging (or noggins/dwangs), particularly for long-span domestic floors. They are generally installed at the centre of a span when floor joists exceed 2.5 m. Spans exceeding 4.5 m may require two rows spaced at 1/3 and 2/3 span.
They may be the preferred option if there is a lot of pipework or cabling to accommodate between joists, as they reduce the amount of drilling that would be required through solid noggings, which would weaken the floor.
A common problem in older dwellings is that floors feel ‘springy’. This can, in part, be because the herringbone struts have been removed in order to run services. Their re-introduction, or the reintroduction of regular noggings can help reduce the problem as the floor is encouraged to behave more as a 'slab' rather than a series of individual joists.
Alternatively, and perhaps more reliably, the floor can be strengthened, by 'sistering' steel, timber or ply reinforcing joists to the side of the existing joists, although, perversely, the installation of reinforcement can be made more difficult by the presence of herringbone struts or noggings.
 Related articles on Designing Buildings Wiki
Featured articles and news
A survey of Leicester’s historic buildings resulted in local listing being taken more seriously.
Demolition is the most high risk activity in the construction sector. Read our introductory article here.
BSRIA report on the domestic boiler market, with China recording the most 'dynamic market uptake'.
Do we really know everything important about the impacts of our infrastructure projects? And if we don’t, does it matter?
Former Chief executive Richard Howson blames government for being 'poor payers'.
An environmental plan is an essential tool for setting and managing environmental objectives for a project.
CLC call for an 'outcome-based, transparent and efficient' industry with new report.
The first NIC assessment suggests there is a golden opportunity to provide low-carbon energy.
It's featured prominently as the backdrop to the World Cup coverage - read about the most iconic building in Russia.
Report highlights growing need for soft skills and digital skills among civil engineers.