The CORE Joist Stiffener range (JSD Double and JSS Single) is designed to reinforce joists when
service penetrations are required. These stiffeners restore strength around openings while
allowing safe passage for services. Manufactured from 1.55 mm galvanised steel, the stiffeners
are available in two versions to suit different joist sizes:
JSD for standard 90 × 140–290 mm joists, and JSS for 45 × 140–290 mm joists
Features & Benefits
- Restores joist strength around service penetrations.
- Two models: JSD (90 mm joists) and JSS (45 mm joists).
- Pre-formed fixing holes for quick installation.
- Made from 1.55 mm galvanised steel for durability.
- Designed for use in internal closed space applications.
Installation Criteria
- Stiffener plates have two types of pre-formed holes: small holes for nails and larger holes for
screws.
- Choose one fixing method only – do not mix nails and screws. All fixing holes must be filled.
- Minimum end distance = joist depth. Minimum edge distance = 40 mm.
- Angles must bear firmly against the underside of flooring (minimum flooring thickness: 19
mm).
- Maximum of 3 penetrations per joist; spacing between penetrations ≥ 2 × joist depth.
- Penetration region must be free from timber defects (knots, splits, warping, etc.).
- Internal closed space use only (NZS 3604:2011 Table 4.1).
