Does uPVC cladding need an air gap?
Yes. Fit uPVC cladding on battens so there is a ventilated cavity behind it. Typical maker guidance is a cavity of at least 19 mm, with a continuous gap of at least 10 mm at top and bottom for airflow, protected by closures that keep out insects and rodents.
What battens should installers use?
Use treated timber battens, usually at least 25 x 50 mm, fixed upright with packers on uneven walls. Keep supports to a maximum of 600 mm centres, closer in high-load areas. Fix cross-battens where boards run vertically.
Why does the cladding need a gap?
- Rainscreen cladding assumes some moisture gets behind it, which must drain and dry.
- Airflow lets the wall breathe and reduces condensation.
- The gap lets boards move with temperature.
What else matters at the base and top?
Keep the start trim clear of the ground (150 mm is a typical figure) and leave expansion allowance as the maker states. Exact figures vary by cladding system, so the manufacturer’s guide takes priority. Never block the vent gaps with trim or sealant.
MLI Building Products supplies cladding, trims and closures for installers from our Worthing trade counter.
Need a trade price? Call the trade counter on 01903 262 636 or visit us at Unit 1, Friar Walk, Worthing. We offer free delivery within 30 miles.
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