7 minute read -
Cutting and Fitting uPVC Cladding: How to Tackle It
uPVC cladding is made of rigid plastic, so you cut it with a fine-toothed carbide-tipped circular saw blade, ideally on a mitre saw or with a circular saw run along a guide. You fit the panels to straight battens over a breathable membrane, start at the bottom with a starter trim and screw each panel through the centre of its slotted holes so it can expand.
Always follow the manufacturer's fitting instructions for spacings, gaps and trims. This guide explains the method and the points where cladding goes wrong most often.
What will you learn in this article?
- What is uPVC cladding and why does it need its own approach?
- What do you need?
- First: removing old cladding
- Step 1: Fit the breathable membrane
- Step 2: Fit the battens
- Step 3: Fit the starter trim
- How do you cut uPVC cladding panels?
- Step 4: Fit the panels
- Working safely with long panels
- Common mistakes
- Maintenance: cleaning uPVC cladding
- Frequently asked questions about uPVC cladding
- In short: cutting and fitting uPVC cladding
What is uPVC cladding and why does it need its own approach?
uPVC cladding comes as rigid plastic boards, with a woodgrain or smooth finish. Well-known brands include Keralit, but the method is much the same for most systems. The panels are light and low-maintenance. Plastic does, however, expand in the heat and shrink in the cold. That is why you do not screw the panels down tight, but through slotted holes with room to move. You also leave space at the trims at each end. Forget this and the panels will bow outwards in warm weather.
What do you need?
- Breathable, waterproof membrane
- Timber battens for the framework, treated or naturally durable
- Starter trim, end trims, corner trims and, if needed, a ventilation trim
- Cladding panels and the screws the manufacturer specifies
- Mitre saw or circular saw with a fine-toothed carbide-tipped blade
- Drill driver, spirit level, tape measure, pencil and sliding bevel
- Safety glasses, ear defenders and work gloves
A mitre saw and drill driver from the Maxxpack 18V range are handy on scaffolding or in the garden, because you do not need to run cables.
First: removing old cladding
Does old cladding need to come off before you fit the new panels? Find out what it is made of first. In the UK, asbestos was banned in 1999, so flat or corrugated cement sheets on buildings built or refurbished before 2000 may contain asbestos. Do not cut, break or drill them yourself. Have the material tested and, if necessary, removed by a licensed asbestos contractor. Your local council can tell you how asbestos waste must be disposed of.
Step 1: Fit the breathable membrane
Fix the membrane to the wall or the timber backing structure, underneath the battens. The membrane keeps out rain and wind but lets water vapour from inside the house escape. Lay the strips like roof tiles, with the upper strip over the lower one, so water runs off to the outside.
Step 2: Fit the battens
The battens decide how flat your cladding will be. Fix them vertically if you are fitting the panels horizontally, so air can flow from bottom to top behind the cladding.
- Check every batten with a spirit level and a long straight edge. Pack out any unevenness with packers.
- Space the battens at the centres given in the manufacturer's instructions.
- Add extra battens at corners, windows and doors, and wherever panels end or a trim is fitted.
- Leave a ventilation gap at the bottom and top, if needed with a ventilation trim to keep out pests.
Where a trim such as an aluminium starter trim is fitted, you can plane the batten down slightly so the trim sits flush and the panel above does not tilt. The instructions for your trim will give the exact amount.
Step 3: Fit the starter trim
The starter trim goes at the bottom, level across the full width. This is your reference line: if the starter trim is out of level, every row above it will be too. Measure from a fixed point and set out the line with a spirit level or laser.
How do you cut uPVC cladding panels?
Cut the panels with a standard fine-toothed carbide-tipped circular saw blade. Coarse teeth tear the plastic edge.
- Mitre saw: the easiest option for square cuts to length. Lay the panel with the face side up, because the blade enters the material from above.
- Handheld circular saw: cut along a guide. The blade cuts from below upwards, so lay the face side down or use a rail with an anti-splinter strip.
- Jigsaw: only for cut-outs, for example around an outside light or a pipe. Use a fine blade for plastic.
Cut steadily and let the saw do the work. If you push too hard, the plastic heats up and the cut becomes ragged. Support long panels along their full length so they do not sag while you cut.
Cutting to length and leaving room
Measure each panel separately. Order panels a few centimetres over length and cut them square to size. At end trims and corners, leave the expansion gap given in the fitting instructions. If you cut in cold weather, bear in mind that the panel will get longer when it warms up.
Avoiding a repeating woodgrain pattern
With woodgrain panels, the same pattern soon shows up if you fit panels from one pack side by side. Mix panels from several packs for a more natural look.
Step 4: Fit the panels
- Clip the first panel into the starter trim.
- Screw it in place with the specified screws through the slotted holes along the top edge. Put each screw in the centre of the slot.
- Drive the screw until the head touches the panel, but do not tighten it down. The panel must still be able to slide.
- Keep to the screw spacing given in the fitting instructions for your panel type.
- Clip the next panel onto the previous one and repeat. Check every few rows that everything is still level.
- Finish the top, corners and window reveals with the matching trims.
Working safely with long panels
- Work with at least two people. Cladding panels are long and sag or swing round if you carry them alone.
- Use a stable scaffold tower or ladder, set up on level ground.
- Keep the work area clear of offcuts so you do not trip.
- Wear safety glasses and ear defenders when cutting. Take the battery out of the saw when you change a blade.
Common mistakes
- Battens not checked, so the cladding ripples
- Starter trim not level
- Screws driven fully home, so the panel cannot expand
- No expansion gap at end and corner trims
- No ventilation gap at the bottom and top
- All panels from one pack side by side, so the woodgrain pattern repeats
Maintenance: cleaning uPVC cladding
uPVC cladding is low-maintenance, but not maintenance-free. Once or twice a year, check for green deposits, dirt or loose trims. Clean the cladding with lukewarm water, a mild all-purpose cleaner and a soft brush or sponge. Do not use abrasive cleaners, solvents or a stiff brush, because they damage the surface. If you use a pressure washer, keep the nozzle well back and do not spray into the joints.
Frequently asked questions about uPVC cladding
Which saw should you use to cut uPVC cladding?
Use a mitre saw or handheld circular saw with a fine-toothed carbide-tipped blade. A jigsaw with a fine blade is handy for cut-outs. Coarse blades leave a ragged edge.
Should you screw cladding down tight or leave room?
You screw the panels through the slotted holes, but not tight. The panel must be able to move as it expands in the heat. Leave room at the end and corner trims as well.
Do you need a breathable membrane behind uPVC cladding?
Yes. A breathable, waterproof membrane behind the battens protects the wall from rain that gets behind the panels, while moisture from inside the house can still escape. Make sure there is ventilation behind the panels too.
Can you fit uPVC cladding yourself?
With a straight wall, good tools and a second person, it is a very doable DIY job. Bring in a professional for a high wall that needs scaffolding, or if your old cladding may contain asbestos.
In short: cutting and fitting uPVC cladding
Start with a membrane, straight battens and a level starter trim. Cut the panels with a fine-toothed carbide-tipped blade, ideally on a mitre saw, and leave room for expansion. Screw the panels through the centre of the slotted holes without tightening them down, work with two people and follow the manufacturer's instructions for every measurement.