Design and EC5 Guidelines

Design Information

  • The integrity of the building or structure must be validated by a suitably qualified Building Designer or Engineer (the “Designer”).
  • The Designer is responsible for determining that the appropriate connector and/or hanger has been selected.
  • Location and spacing of straps must be specified by the Designer.
  • When selecting the appropriate connector and/or hanger, consideration must be given to the safe working loads or characteristic capacities required, bearing support and connection details within the building or structure.
  • For all Engineered Wood Products (EWP), ITW Construction Products recommends the hanger height be at least 60% of the joist height for lateral stability.
  • Any bespoke Cullen product designed by ITW Construction Products but manufactured by another (unless directed to by ITW Construction Products) will not be covered under ITW Construction Product‘s warranty.
  • ITW Construction Products reserve the right to (i) change the design specifications and applications of any connector/hanger, or (ii) withdraw any connector or hanger without giving prior notice.

Galvanised Protection

Z275 galvanised coating is the minimum corrosion protection recommended for Service Class 2 applications (BS EN1995-1-1 Table 4.1 Examples of minimum specification for material protection against corrosion for fasteners).

Z600 galvanised coating gives a greater corrosion protection for use with masonry applications (BS EN845-1 Annex A1, Table A.1 Materials and corrosion protection systems).


Eurocode 5 (BS EN1995-1-1)
Presently timber designs in the UK can be carried out using national standards BS 5268 part 2 & 3 or using BS EN1995-1-1 (Eurocode 5). Eurocode 5 is the harmonised European Standard covering the design of timber structures.

The purpose of the Eurocodes is to establish a common set of standards for the design of buildings across all European member states, although each member can have its own National Annex which is used in conjunction with the Eurocodes for design.

What does this mean for our products?

In addition to publishing safe working loads that have already been factored down, characteristic values for each product will be published. The characteristic value is the lower 5th percentile value obtained from test results.

A series of modification factors must be applied to the characteristic value to determine the Design Value.

Technical Approvals

All timber-to-timber hangers are tested to meet the requirements of ETAG 015 Guideline for European Technical Approval of three-dimensional nailing plates, which allows the hangers to be submitted for a European Technical Assessment which once issued enables the products to be CE Marked.

All timber-to-masonry products (hangers, straps and wall ties) are tested to meet the requirements of BS EN845-1 enabling them to be CE marked.  Fasteners for timber structures (nails, screw and bolts) are tested to meet the requirements of BS EN14592 enabling them to be CE marked.

If you have any questions regarding these guide lines please use the form below: