How to properly ventilate cladding

August 19, 2020 at 12:06 PM

After speaking to various customers and installers over the last year or so, it has become apparent that there is a need for advice around how to properly ventilate cladding.

Our Technical Manager, Dave Osborne has recently given his thoughts on this, with a step by step guide and some useful hints and tips along the way:

Before we start, I would like to highlight the key difference between white and colour/foil installations, particularly given the development of darker colours (Anthracite Grey, for example) as an increasingly popular choice within the marketplace. Our white cladding is more forgiving but if you don’t follow the exact guides for colour/foil installations then you will encounter problems. We do, however, recommend that you follow these guidelines for both white and colour/foil to ensure that you get the best possible installations.

For all installations, preparation is key! New projects require sound substrate, good quality battens (suitable treated timber), insulation (if required) and a vapour membrane. Replacement of existing cladding requires removal of the old material, checked and repaired substrate to ensure sound location for battens, good quality battens, insulation and vapour membrane, as for new projects.

Below is my step by step guide for both white and colour/foil installations:


  • We recommend using 25mm x 38mm battens (19mm x 38mm min)
  • Install battens with appropriate fixings for the substrate. Do not install horizontal bottom batten as this will block ventilated air-path
  • Fix battens at max 600mm centres
  • Ensure battens are fixed around the door and window openings to allow plank ends to be nailed
  • If required, or where insulation is inserted, always install a vapour breathable membrane behind the cladding battens to ensure the air path is not obstructed
  • Fix rigid perimeter trims first using 25mm A4 stainless steel ring shank pins. Where 2 pt. trims are being used, only fix the back part
  • Locate first cladding plank in starter trim and nail to battens using 30mm A4 stainless steel ring shank pins. Ensure all plank ends are fixed to a batten
  • Interlock subsequent planks, fully engaging tongue and groove detail, and fix to battens
  • Joints in long runs must be made over a batten to ensure plank ends are fixed
  • Once the total area is clad, finish perimeter trims by snap fitting front part of any 2 pt. trims


  • We recommend using 50mm x 50mm battens – NO COMPROMISE - if 25mm x 38mm battens are used because of restrictions on available space, this will NOT be covered by our guarantee
  • Install battens with appropriate fixings for the substrate. Do not install horizontal bottom batten as this will block ventilated air-path
  • Fix battens at max 400mm centres
  • Must ensure that the 50mm air-path is open both at the base and the top edge of the cladding to create a clear draw of air directly behind the cladding. This can be covered with a suitable vent trim to stop insect ingress
  • Follow same installation procedure as for white

Dave Osborne is the Technical Manager for Cellular PVC cladding specialists Swish Building Products. For more detailed guidance, we also recommend readers to refer to the Swish Design and Specification Guide and to the Plastics Industry Code of Practice, available from The British Plastics Federation.

If you have any questions for Dave or the team, please use the following contact details to get in touch: