Vapour Permeable Roofing Underlay

Untaped

125gsm Weight Untaped Harcon VPU

Untaped Harcon VPU is a range of premium quality underlays with superb vapour permeability expanded to offer 3 weight options with the 125gsm roofing membrane available as standard. 

features

  • Exceptional nail tear and strength
  • 3 weight options available
  • Highly vapour permeable
  • Condensation control
  • Complies with BS5534:2014

ideal for

  • Warm roof structures
  • Cold roof structures 

guidance

Refer to the Harcon VPU installation guide for complete installation instructions.

Material
The 125gsm membrane has a 3 layer composite structure with the vapour permeable film bonded between two layers of non-woven polypropylene. 

VPU Weight Options:

  • 92gsm budget weight
  • 125gsm standard weight
  • 230gsm heavy weight

 

Harcon VPU Taping Requirements

Recent changes to BS 5534: 2014 (Code of practice for slating and tiling for pitched roofs and vertical cladding) relating to wind uplift requirements, now require some membranes to be taped in highly exposed locations. Refer to tables for the appropriate taping requirements for Harcon VPU range of membranes. 

 

Material Properties 230gsm  125gsm 102gsm
Thickness (mm)  0.75 0.50
0.40
Mass per unit area (g.m-2)  230 125 102
Roll length (m)  50 50
50
Roll width (m)  1/1.5 1/1.5
1
Colour  Grey Blue Grey

Tensile strength (N.50 mm-1)

Longitudinal

Transverse

 

470

300

 

285

165

 

 250

 140

Elongation (%)

Longitudinal

Transverse

 

70

100

 

70

90

 

60

70

Tear Resistance (N)

Longitudinal

Transverse

 

300

390

 

125

120

 

100

95

Watertightness

Unaged

Aged

 

W1

W1

 

W1

W1

 

W1

W1

Water vapour transmission (Sd) (m)  0.029 0.029 0.029
Vapour resistance (MN.s.g-1)  0.145 0.145
0.145
 Fire Properties (EN 11925-2 : 2002)  Class D, d2 Class D, d2   Class D, d2

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