- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 30 Oct 2017
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
Book review – a series of essays about architecture and urbanism in the British Empire.
The complex situation where events occur at the same time.
How can Latin America and the Caribbean unlock the digital potential of their new and existing built environment?
CIOB publish a new code of estimating practice.
These relate to a programme where each activity is allocated a price and interim payments made against completion.
Police testing finds that flat door could only withstand fire for half its designed time.
Have a look at these images from a new photography book of buildings being reclaimed by nature.
What does the phrase 'demised premises' mean? Find out here in our introductory article.
New good practice guidance looks at the best way to deliver multi-functional solar car parks.
Philip Hammond suggests the public finances have reached a turning point.
Support grows for the Construction (Retention Deposit Schemes) Bill.