EN 15737:2009

Overview

EN 15737:2009 is a European standard developed by CEN (European Committee for Standardization) that specifies a test method for determining the torsional resistance to driving screws in timber materials. This standard is essential for evaluating the performance of screws used in solid timber, glued laminated timber, and other wood-based materials, ensuring reliable and durable timber structures.

The standard defines procedures and criteria for measuring the torsional strength and resistance during screw insertion, which is crucial for the quality control of timber fasteners and structural timber components. It supports compliance with EN 14592 requirements related to dowel-type fasteners.

Key Topics

• Scope and Application
  EN 15737:2009 applies to test methods for screws driven into solid timber, glued laminated timber, or other wood-based materials, focusing on torsional resistance characteristics.

• Test Setup and Equipment
  The method uses a moment cell to measure torque during screw insertion and displacement transducers to record vertical movement. The setup ensures precision by requiring:

  • Accuracy within 1% for torque measurement.
  • Controlled screw insertion speed (≤ 100 revolutions per minute).
  • Proper fixing of test specimens to avoid movement.

• Material and Sampling Requirements
  Test pieces should be conditioned to an equilibrium moisture content at 20 ± 2°C and 65 ± 5% relative humidity. Density and grain direction of the timber are critical to ensure representativeness and consistency.

• Test Procedure
  Screws are installed according to manufacturer instructions, including pre-drilling if necessary. Maximum torque recorded prior to screw head contact defines the torsional resistance.

• Reporting Requirements
  The test report must detail:

  • Screw specifications, material type, moisture content, and dimensions.
  • Test conditions including temperature, humidity, and equipment.
  • Results showing maximum insertion moment and penetration depth.
  • Influencing factors such as pre-drilling and screw orientation.

Applications

EN 15737:2009 is widely applied in the construction, timber engineering, and fastener manufacturing industries for:

• Quality Control of Screws in Timber Structures
  Ensures screws meet performance requirements before market release or during production.

• Design Validation of Timber Connections
  Provides data for verifying connection strength and durability in structural engineering designs.

• Research and Development
  Facilitates performance comparison between different screw types, materials, and coatings under controlled conditions.

• Standard Compliance and Certification
  Assists manufacturers and testing laboratories in meeting European standards, linking to EN 14592 requirements for dowel-type fasteners in timber.

Related Standards

• EN 14592:2008 – Timber Structures – Dowel Type Fasteners – Requirements
  Specifies product requirements that complement the testing methods for screws as detailed in EN 15737.

• ISO 3130 – Wood – Determination of Moisture Content for Physical and Mechanical Tests
  Defines the procedure for determining moisture content, crucial for conditioning timber test specimens.

• ISO 3131 – Wood – Determination of Density for Physical and Mechanical Tests
  Provides methods for measuring the density of wood, essential for material characterization in testing.

Summary

EN 15737:2009 offers a rigorous, standardized test method for assessing the torsional resistance of screws driven into timber-based materials. It supports enhanced safety, performance reliability, and compliance in timber construction by providing clear guidelines on sample preparation, test setup, execution, and reporting. This standard is an important tool for architects, engineers, manufacturers, and quality assurance professionals engaged in timber structure design and assessment.

Keywords: EN 15737:2009, torsional resistance, screw insertion, timber structures, test methods, glued laminated timber, wood-based materials, screw testing, timber fasteners, structural timber, CEN standards.