An alternative to vapour control layers, which seals side lap joints on walls and roofs to reduce condensation and to maximise air tightness.


  • Can be applied in cold conditions without reduction in long term performance
  • Unique high tack adhesive for instant grab
  • Special high strength non-tear laminated film
  • Supplied in self-wound rolls for easy application
  • Service life can exceed 20 years
  • Very low moisture vapour transmission rate
  • Reduces condensation in built up metal roofing systems
  • Prevents air leakage through lap joints
  • Outstanding adhesion to coated steel and aluminium sheets without the need for primers

Polyband® is an extruded butyl tape laminated with a fixed polyester liner.

Product uses

  • A high performance Air Seal and Moisture Barrier Tape developed especially for sealing side lap joints of metal roof and wall liners to reduce condensation and increase airtightness in buildings
  • Care must be taken to seal the joints at the eaves, ridge and any pipe or service penetrations in order to provide a completely airtight building
  • Polyband® can be used as recommended in the MCRMA Technical Paper No.14 Guidance for the Design of Metal Roofing and Cladding to comply with Approved Document L2:2006
  • The use of GCA preformed butyl sealant is recommended for sealing between the end laps


Click here to download the technical data sheet


Technical Approvals

Polyband® has been independently tested by the Building Research Establishment for sealing metal liners in a built up roofing system (Report No. 16573; 4/2/00). Its performance in reducing the passage of moisture vapour was compared with transmission rates obtained for unsealed liners both with, and without a vapour barrier membrane. The tests demonstrated that when used as recommended, Polyband® was approximately 50% more effective as a barrier to the passage of moisture vapour than a conventional vapour control layer (VCL).

Polyband® conforms with the following for the sealing of side lap joints:-

MCRMA Technical Paper No. 14 – Guidance for the Design of Metal Roofing and Cladding to Comply with Approved Document L2:2006.
The report recommends that side and end laps/joints and all perimeter joints should be effectively sealed, not only to reduce air leakage to a very low level, but also to provide vapour control.

Approved Document L2:2006, Section 1, Elemental Design Method (Summary).
Thermal bridging at junctions and around openings:- 1.9 Construct the building fabric so that there are no significant thermal bridges or gaps in the insulation layer(s) within the various elements of the fabric, at the joints between elements and at the edges of the elements. 1.11 Adopt robust design practices illustrated in MCRMA Technical paper No. 14 and BRE Information Paper IP 17/01

Building Air Leakage Standards:-
1.17 Buildings should be reasonably airtight to avoid unnecessary space heating and cooling demand and to enable the effective performance of ventilation systems. 1.19a Provide reasonably continuous air barrier in contact with the insulation layer over the whole thermal envelope (including separating walls). Guidance for the design of Metal Cladding and Roofing Systems to minimise air infiltration is given in the MCRMA Technical Paper No. 14.