Modern Plaster Mouldings - What Are They Made Of?

November 27, 2019
Gone are the days when cornice and crown ceiling mouldings are constructed of pure plaster. The material is very heavy and difficult to repair if damaged. There are companies who say wood is best because it is lightweight and easily carved. The problem with wood (pure wood or MDF) is that it always splits and cracks within one to two years because of temperature and humidity changes in the typical Canadian home.

Then there are PVC mouldings, which are made through injection, requiring the use of moulds. Like wood, the selection is limited to flat and shallow profiles to save on costs. The only way to achieve a detailed design would have to be done by layering and nailing sections together. These would eventually split due to environmental factors. Also PVC is plastic, and it looks like plastic. (It fits well in certain situations such as vinyl siding exteriors but if your façade is, for example, brick, you may want to consider our mouldings that are authentic in finish and a genuine fit on any exterior.)
Perfect Plaster Cornice Sample Laser Line - Fine Finish Wall Systems Bradford
Plaster Mouldings
Installation of PVC mouldings also requires consideration of expansion and contraction due to shifts in temperature. Manufacturers recommended leaving a 1/8” gap over 18’ spans which are then filled with caulking, leaving a visible seam.

Considering the deficiencies and drawbacks of plaster, wood and PVC, the modern solution to interior and exterior architectural mouldings is EPS – Expandable Polystyrene. For interior spaces, EPS is coated in plaster.

For exterior applications, the EPS is coated in a modified polymer cement rather than plaster. EPS is a highly durable material used in a large number of consumer products. It is environmentally friendly not only for it’s long-lasting durability and heat-insulating qualities, but EPS has never contained CFCs, HCFCs, HFCs or formaldehyde – all of which are chemicals harmful to the environment. EPS is inert and stable and does not produce methane gas or contaminating leachates. The extrusion process allows the manufacturer to create any detail and any size in one piece with no seams at an economical price point.
Because EPS mouldings are a custom product, the exact profile needed is what is produced and installed: any shape is possible! Homeowners can choose their profile from a catalogue, but if a specific profile is required, or a match to something already in your home is required, it is a simple process. A computer software automates a heated wire to cut the exact profile out of a block of EPS, which is already in its final state of hardness.

Here is a great video of the extrusion process used.

An added bonus is that once complete, EPS mouldings do not require the use of nails for installation, so the final finish will be much more consistent with no holes to patch. Ultimately, their integrity and durability are second to none and literally require no maintenance for the life of the product. We have one client who had his plaster cornice installed in 2009 (10 years ago) and we call him back every year – it’s like a running joke now, that he has “nothing to report”. He is one of our happiest customers.

If an EPS plaster moulding is damaged (from water or structural shifting or impact), then repair is easy and seamless. We simply cut out the affected area, get the profile matched, triple-coat it, wet-sand and re-paint. Voila!

It takes a skilled craftsman to install EPS mouldings properly, where the proper substrate and moisture barrier are implemented, and expert application of the finish coats. Learn more about our professional service.
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Jason Harper

Jason Harper formed Fine Finish Wall Systems after he became disillusioned with trades in the construction and renovation industry. He was tired of seeing people getting ripped-off and exploited by under-qualified and unscrupulous contractors who are only interested in getting paid. These so-called professionals fail to learn or understand the basic science behind their trade, and often leave homeowners stranded and out of pocket. Homeowners deserve excellent quality work, performed by professionals who are knowledgeable and experienced. It is Jason’s goal and mission to bring back pride, quality and purpose to the construction sector.
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