PHS Sd Variable Plus

PHS Sd Variable Plus is a triple layer, high performance membrane, designed to adapt to its environment and alter diffusion rates accordingly, excellent for flat roof builds.

  • Robust & Flexible
  • Highly Tear-Resistant
  • Variable Diffusion Resistance
  • Moisture Variable, Sd value 0.4-35m
  • Suitable for Air-Injected Insulation & Insulation Mats



Declaration of Performance


PHS Sd Variable Plus Membrane is a triple layer fabric, high performance membrane, made from non-woven PP fabric.

PHS Sd Variable Plus is a robust airtight membrane with a variable Sd value. It’s reinforced mesh material is designed to create an airtight barrier within the home. With variable diffusion resistance, this membrane can adapt diffusion rates depending on the environment. The membrane creates an airtight layer that dynamically adjusts based on the humidity of the environment, preventing condensation build up and moisture damage. PHS Sd Variable Plus is highly recommended for flat roof builds.

Technical Details

Tensile strength (DIN EN 12311-1)* 387
Roll Weight (kg): 7.7
Weight (g/m2): 0.103
Roll Lenght (m): 50
Roll Width (m): 1.5
Roll Area (m2): 75
Colour: White Transparent
Water Vapour Transmission (Sd) (m): EN 12572 0.4 – 35m
Resistance to Fire: class E
Nail Tear Resistance (EN12311-1): 230
Elongation (EN12311-1): 24%
CE certificate: passed
Moisture resistance:ย  u = 108074
Water Penetration Resistance: passed
CE Certificate:



  • Lay the membrane so that the printed side is facing the fitter.
  • Lay the sheet parallel or at a right angle to the rafters with an overlap of at least 10cm.
  • Ensure flush-mounted bay insulation, there should be no cavities between the bay insulation and membrane.
  • The membrane is translucent making it easier to see markings, measurements and fixtures.
  • Fit the membrane free of tension and avoid creases.
  • Overlaps, component joints and penetrations must be made airtight with PHS sealing products including tapes and sealant.


Part Number: Size:ย  Box Quantity:ย  ย Barcode:
AR9093A 1.5mx50m 1