Thermafleece Breather Membrane Insulation
Thermafleece Breather Membrane

Key Facts

  • Width (mm) – 1500
  • Thickness (mm) – <1
  • Highly Breathable
  • Manufactured to ISO 9001 & 14001
  • Can be recycled
  • Vapour Open
  • High Tear Strength

Thermafleece Breather Membrane

Thermafleece Breather Membrane is a light weight vapour permeable underlay designed for use in floors and walls or on top of insulation as a protective layer.

The material meets EN 13859-1 for pitched roofing and EN 13859-2 for walls. Thermafleece Breather Membrane has good water resistance, high breathability and is lightweight and easy to handle.  The membrane is coloured light-grey on one side and white on the other with no text or images on either side, except a 150mm overlap line.

Thermafleece Breather Membrane comprises 3 layers; two outer layers composed of a non-woven polypropylene and an inner breathable microporous film.

Installing Thermafleece

Installation Guidelines for Walls

Fix the membrane to the wall structure; ensure upper layers overlap lower layers. Work from the bottom moving upwards and ensuring there are minimum overlaps of 100 mm on the horizontal joints. Do not begin a vertical lap joint within 300 mm of a corner, and vertical laps should be at least 150 mm. Ensure the bottom timber is also protected by an overlap. Fix at suitable intervals with galvanised nails, stainless staples or similar fixings that will be permanent.

Do not leave the membrane unnecessarily exposed to weathering since high winds; excessive UV etc. may cause damage over time. If you are required to leave the membrane exposed for extended periods of time, consider the use of suitable temporary protection materials.

Installation Guidelines for Floors

Thermafleece Breather Membrane is ideal for supporting insulation between suspended floor joists or as a protective layer above insulation installed between floor joists to prevent the accumulation of debris on top of insulation.
The membrane can be nailed or stapled to the underside of the floor joist if access permits.  Alternatively the membrane can be installed from above the rafter.  For best performance staple the membrane to the lower side of the joist and run the membrane across before stapling to the lower side of the next joist before running over the top of the joist and repeating.   Ensure an overlap of at least 100mm between layers of membrane.

Thermafleece breather membrane can also be laid on top of loft insulation to keep the insulation clean and free of debris.

Further Guidance

Always handle carefully to prevent tears and punctures. Repair any damage which does occur with suitable tape. Ensure that sufficient ventilation is incorporated to comply with all relevant building regulations and technical standards. Store all materials in suitable conditions.


Cutting Tips

Thermafleece Breather Membrane can be cut with a sharp edge knife or scissors.  Take care not to puncture membrane when cutting and repair any damage which does occur with suitable tape

Tensile strength: 185/85 N/50mm (MD/CD)

Elongation: 50/70 % (MD/CD)

Tear resistance: 75/95 N (MD/CD)

Resistance to air penetration: 0.045 m3/m2.h.50Pa

Water vapour transmission properties: 0.03 Metres

Resistance to water penetration: Class W1

Flame resistance: F

Stability to low temperature: -40oC

Artificial ageing – elongation: 40/45% (MD/CD)

Artificial ageing – tensile Strength: 160/75 N/50mm (MD/CD)

Artificial ageing – resistance to Water Penetration: Class W1


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