ISO 18393-1:2023

Overview

ISO 18393-1:2023 specifies a laboratory test method for determining settlement of loose-fill insulation installed horizontally in ventilated attics. The standard quantifies how humidity and temperature cycling affect the installed thickness (settlement) of blown loose‑fill insulation over time. It replaces the 2012 edition and is intended for manufacturers, test laboratories and specifiers concerned with long‑term thermal performance of attic insulation.

Key topics and requirements

• Scope: Settlement measurement of loose‑fill insulation in ventilated attic conditions, simulating humidity and temperature cycles.
• Specimen preparation: Material may be pre‑conditioned per ISO 12570. Insulation is blown into a specimen box to an installed thickness of 300 mm (or higher in larger boxes) and the installed density is recorded.
• Specimen container: Box internal dimensions typically 600 mm × 600 mm × 300 mm (height) with tolerance; nine measurement positions across the base.
• Climate chamber conditions: Chamber must control from (5 ± 1) °C to (60 ± 1) °C and (15 ± 5) % RH to (85 ± 5) % RH.
• Test cycles: Four cycles, each composed of two 14‑day periods:
  • Period 1: 14 days at (23 ± 1) °C and (85 ± 5) % RH
  • Period 2: 14 days at (50 ± 2) °C and (15 ± 5) % RH
• Measurements: Thickness recorded at nine positions to the nearest millimetre at fixed intervals and at least at the end of each period; readings used to calculate percentage settlement.
• Number of specimens: As specified in the product standard; if unspecified, at least two specimens.
• Conditioning: Standard conditioning at (23 ± 2) °C and (50 ± 5) % RH until constant weight; alternate tropical conditioning available (27 ± 2 °C, 65 ± 5 % RH) with reporting.
• Reporting: Test report must include product identification, initial and conditioned thickness/density, detailed test procedure and all individual mean values and settlement results.

Applications and users

ISO 18393-1 is practical for:

• Manufacturers validating installation guidelines and declared performance of blown loose‑fill insulation.
• Independent test laboratories performing standardized settlement testing for certification or regulatory compliance.
• Product developers and R&D teams assessing material formulations and long‑term performance under simulated attic climates.
• Building specifiers and energy assessors evaluating insulation durability, installed density recommendations, and lifecycle thermal performance in ventilated attics.

Keywords: ISO 18393-1, settlement test, loose-fill insulation, ventilated attic, humidity and temperature cycling, installed density, climate chamber testing.

Related standards

• ISO 12570 - referenced for moisture content determination and sample conditioning.
• ISO 18393 series - other parts of the settlement test series are listed on the ISO website.