UT Blue /White

Under tile waterproofing 250m U.T BLUE/WHITE2 laid over rafters under tiling battens

U.T. Blue/white is a polyethylene membrane that has been specially formulated for use under roof tiles.
It is 0.25 mm in thickness and made in rolls of 1.5 x 30 m. U.T. blue/White2 is dimensionally stable, light in weight, translucent, and weatherproof; handling and installation are easy, and it seals around nails. It is used for the prevention of draughts and dust penetration into the roof spaces through tiles and slates, and prevents damage to ceilings, rotting of timbers, and corrosion of pluming, rotting of timbers, and corrosion of plumbing. Dust has also been known to penetrate between cornices and walls, initiating or aggravating allergies in susceptible people. The membrane is also designed to prevent moisture from warm damp air reaching and condensing on ceiling boards and other vulnerable points in the building fabric. U.T Blue/White2 also prevents strong wind from lifting and ripping off roof tiles.
Most building societies insist on the use of undertile membrane where the roof pitch is less than 262 or more than 452 and in exposed coastal areas.


  • Tensile strength, N/mm of width, min 2.16
  • Elongation at break, % min 200
  • Puncture resistance, N/mm of thickness, min 29.0
  • Tear strength, N/mm of thickness, min 65.0
  • Resistance to accelerated weathering retention of breaking strength, % 90
  • Retention of elongated at break % 90
  • Light transmittance, % min 35
  • Water vapour transmission,g/m2/day, max 2.9
  • U.T. Blue/White2 has a long history of success and has been used in many large housing contracts.

Closed detail:

Turn down the U.T. BLUE/WHITE2 over the fascia board at the eaves and seal into the gutter.

Open Soffit detail
Boarding to be used at open eaves to carry the U.T BLUE/WHITE2 to the gutter. The boarding gives added security to the structure because it prevents wind-lift of tiles from the underside of the open soffit.


One layer of 250 m2 U.T BLUE/WHITE2 weatherproof sheeting, installed over common rafters and under battens to recive tiles.
Allow a minimum overlap of 100 mm.

UT Blue is a co-extrusion consisting of the following:

  • Top layer
    UV stabilised virgin material with white master batch;
    60 micron thick
  • Middle layer
    White virgin polyethylene;
    60 micron thick
  • Bottom layer-
    Blue master batch with virgin polyethylene (heat stabilised);
    60 micron thick

The three layers provide a material which has the strength of a 250 micron SABS underlay and has superior weathering and ageing properties, compared to the SABS 952 Type E specification.


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