Rendering

Rendering Mouldings

Decorative external mouldings — sills, cornices, band courses and architrave profiles — in coated polystyrene and cement-based products.

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Rendering Mouldings products

Rendering Mouldings buying guide

Fixing and weathering

Mouldings must be both adhesive-fixed and mechanically fixed on anything above ground level. Every horizontal top surface needs a fall and a drip groove on the underside, or water will run back against the wall and stain the render below within a season. The drip groove is the detail most often left out and the one that causes the most visible staining.

Polystyrene versus cement mouldings

Coated polystyrene is light, easy to cut and fix, and needs no structural support — which makes it the practical choice for large cornices and band courses at height. Cement mouldings are far more impact resistant and appropriate at ground level or anywhere they may be knocked, but they are heavy enough to need real mechanical fixing and, on large profiles, structural consideration.

Jointing and expansion

Butt joints between lengths will open up as the wall and the moulding move at different rates. Leave a small gap at each join, fill it with a flexible sealant rather than render, and reinforce over the join with mesh in the base coat. Long uninterrupted runs need periodic movement joints on the same basis as the wall render itself.

Setting out

Mouldings are horizontal reference lines that the eye reads instantly, so any deviation is obvious even at a distance. Set them out from a laser or string line across the whole elevation rather than measuring up from a window head that may not be level. Check the line again once fixed and before rendering — correcting it afterwards means removing the moulding.

Frequently asked questions

Can polystyrene mouldings be rendered over?
Yes — most are supplied pre-coated and take a mesh-reinforced base coat and finish coat as part of the wall render system.
Do mouldings need mechanical fixing?
Above ground level, yes. Adhesive alone is not adequate for anything that could fall.
What is a drip groove for?
It breaks the surface tension so water drips clear of the wall instead of running back underneath and staining the render below.

stocked at both jaden services trade counters — fairfield heights and prestons — with australia-wide delivery and trade pricing for regular accounts. Get in touch