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Houses and buildings that may be affected Recommended actions for affected property Houses and buildings that may be affected
Between 1970 and 1997 some prefabricated roof trusses were constructed using nail-plates which have since proven faulty. These nail-plates used a nail which can potentially work its way out of timber trusses over time. Affected trusses could be susceptible to failure, including potential collapse, depending on the load they are bearing. Tiled roofs are particularly susceptible.
Houses built before 1970 and after 1997 are not affected as the pre-fabricated roof trusses that used the particular nail-plate were not produced outside those dates.
If you are unsure of your building’s construction date, the
local council planning/building department may be a source of this information.
It is not known which buildings have the particular nail-plate in their roof trusses. An on-site inspection is required to determine whether a roof may be affected.
This table summarises the potential risk for houses built between 1970 and 1997.
Roof frame type | Roof covering |
Iron | Tiles | Other |
Steel | No risk | No risk | No risk |
Conventional timber framing | No risk | No risk | No risk |
| Timber trusses | Low risk | Affected | Low risk |
1. Timber framing - Conventional timber roof framing has all of the separate timber members connected using nails and in some instances narrow steel strapping (like a ribbon).
2. Timber Trusses - Prefabricated timber truss framing consists of a series of parallel timber frames where the timber members are connected by rectangular flat steel plates that appear to be perforated.
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Recommended actions for affected properties
Houses Most houses have a large number of internal walls so there is little likelihood of complete collapse, however any signs of movement such as sagging of the ceiling or dents in the ceiling cornice should be checked by an experienced builder, building surveyor, designer or structural engineer.
Commercial/public Buildings with large open areas are most prone to collapse if a failure of the roof framing occurs.
For buildings which are used by significant numbers of people it is strongly recommended that building owners have the roof framing checked by a structural engineer and that the council is advised of the outcome for its records.
Buildings that should be considered include:
- supermarkets
- community halls
- libraries
- churches
- club/restaurant/hotel dining rooms
- nursing home lounge and dining rooms.
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