Where Do Cladding Trims Go?
A Guide For Cedral & James Hardie.
A plain-English guide to which trim goes where on a Cedral Weatherboard or James Hardie Plank installation — start profiles, corner trims, window reveals, vents and end profiles.
Five trims, five
jobs to do.
Every cladding trim on a Cedral or James Hardie installation has a specific job — kicking the first course out, protecting a cut edge, sealing a corner, or keeping insects out of the cavity while still letting it breathe. The diagram below shows roughly where each one sits on a typical elevation; the numbered guide underneath explains why.
What each trim does
— and where it goes.
Start profile (base of the wall)
Fitted horizontally along the bottom of the batten run before any boards go up. It kicks the first course of boards out slightly so it sits at the same angle as the lapped boards above — on Cedral Lap this typically creates a 21mm kick-out. You'll also need a start profile above any window or door head where a full board doesn't run across.
External corner trim (symmetric or asymmetric)
Fitted vertically at every external corner, again before the boards are installed. Symmetric corners give a neat mitred look either side; asymmetric corners (sometimes called window reveal profiles) are used where one return is narrower, such as a window reveal. Boards then butt up against the trim on each face.
Connection trim & window reveals
Around window and door openings, a connection profile is fixed vertically at the sides to hold the cut board edge in place, and horizontally above the head. Leave the gap specified for your board type between the trim and the window sill or frame — typically around 10mm — so water can drain away rather than sitting against the frame.
Perforated closure / flyscreen vent
Fitted at the top and bottom of the ventilated cavity behind the boards, and above and below window and door openings. It closes the gap against birds, insects and debris while still allowing the cavity to breathe — essential for keeping the battens and breather membrane dry over time.
End profile
Used to protect and finish any cut board edge that's left exposed — for example where cladding meets a soffit, or finishes as a single piece on a window reveal rather than returning into a corner. It caps the cut fibre-cement edge so it isn't left raw to the weather.
Trim fitting, answered.
Do trims go on before or after the cladding boards?
Before. Start profiles, corner trims and connection profiles are all fixed to the battens first, and the boards are then cut and fitted around them.
Do I need a breather membrane as well as trims?
Yes — the breather membrane sits behind the battens and boards, separate from the trims, and works alongside the perforated closures to keep the cavity ventilated and dry. We supply membrane and EPDM tape alongside our trims and screws.
Can trims be colour matched to my boards?
Yes. See our Cedral colour range and James Hardie colour range pages, or get in touch with your board colour and we'll confirm what's available.
Is this guide a substitute for the manufacturer's fixing instructions?
No — this page is a general overview to help you work out which trim you need where. Always follow Cedral's or James Hardie's official fixing guide for exact spacings, fixing centres and gaps for your specific board type before installing.
Not sure which
trims you need?
Send us a rough sketch or a few photos of the elevation and we'll confirm exactly which trims, screws and accessories to order.
Email us →