Green tips on plasters

When deciding about what sort of wall covering we would like to have in our interiors, it is important to review and understand the different options and possibilities we have. I am not talking about wall paper or paint, but about what is underneath and what could be the feature, the plaster.

I am going to refer to one of my favourite book "Sustainable Residential Interiors" by Kari Foster, Annette Stelmack and Debbie Hindman.

Do we think about plaster as a finish? Not very often, which is a sad thing as Venetian plaster is just a wonderful finish that will give a particular identity to a home. But, we’ll talk about venetian plaster later. When we hear "plaster" what comes in mind is the finish we need to make our walls smooth so that we can add a coat of paint, wall paper or any other sort of wall covering. The role of plaster is an important one as it participate to the structure of the wall, it has thermal properties and is fireproof. A mineral based plaster with no additive is basically inert and dry and will particularly suit people with chemical sensitivities. Walls made out of plaster breath and adapt to climate changes and allows water vapours in and out, improving indoor air quality. Because plaster can breath, it is important not to add any toxic chemical additive in the plaster as these would be exhaled.

Gypsum plaster

The most known plaster is gypsum plaster. Its main component is hydrous calcium sulfate, an abundant mineral dehydrated at about 300F into powdery substance, then remixed with water for application on walls. Gypsum has to be mined and transported, which is one drawback.
There also are available synthetic gypsum or by-product gypsum. This recovered gypsum fills an eco-niche by reducing waste and landscape destruction.Gypsum plaster is only used indoor as the rain and weather would erode it.
Other minerals, including lime, can be added. Many gypsum plasters today contain harmful fungicides, setting agents and other chemicals. Specify natural gypsum plaster with no or low-VOC additive, if possible. The mineral gypsum in the plaster is not considered harmful to the environment, but chemical additivies could leach into land or water upon disposal.

Portland cement plaster

Cement plaster is made from portland cement, sand lime, and water. The most likely place to use cement plasters indoor are basements, fireplaces and masonry walls. It is not often used indoor.

Lime plaster

This is an ancient building material. Lime derives from mined limestone, crushed and fired at very high temperature (1600 to 2100F) to make quicklime which becomes with water lime putty, the main ingredient of lime plaster. Dehydrated lime putty is combined with sand and water to form the plaster. This process is lengthy and energy intensive. The positive aspect is that it will completely degrade back into limestone.
Lime plaster is inert and is a healthy option for a green home. It is the hardest and most durable of all interior finishes and can be used in very humid climates. If marble dust is added to plaster and the finish is polished it is called Venetian plaster. Natural pigment can be added to add colour. You should specify lime without synthetic additives and natural/mineral pigments. Avoid wall coverings or traditional paints on lime plaster.

Venetian plaster

It was developed in the 1500s to imitate the polish beauty of marble. It is made of lime and marble dust , applied in several thin layers then burnished, sanded or polished. In this way, the beauty of natural stone, without the weight or expense of real marble, was achieved. Traditional Venetian plaster is an earth-friendly, mineral-based option that dries to an inert, no VOC, non allergenic surface. Synthetic acrylic resins or pigments are often added, but all natural products are preferred for green homes. Avoid any binders that out gas high level of VOCs.

Earthen plaster

Earthen plaster or mud plaster is as ancient as human kind, has the permanence of rock, and yet the modern look of suede. Although more traditionally used on homes built from staw bales, cob, adobe, or rammed earth, it can also be applied over drywall.
Earthen plaster has the least embodied energy of any building material. The best recipe for durability lies in the regional soil. If the home site has suitable clay available the earthen paster can be made with it. (Before proceeding, check for any toxic contaminant). Traditional earth plaster recipe include some of the following ingredient: clay dirt, sand, straw and cooked flour paste or manure.
Commercial clay plaster may be purchased, with as primary ingredient, earth (clay) mineral pigments, and borax. Primers and sealants available from the clay mix suppliers, are specifically designed for eco-friendly homes and will usually be nontoxic, solvent free, and low or no-VOC.
Unfinished earth plasters is best suited for dry ecosystems and well-ventilated home environments, as humidity will compromise the plaster integrity. Commercial sealents sole most moisture-related problems for the purchased clay plaster veneers. As earthen plaster will completely biodegrade to its original component it is a very good example of cradle to cradle building material!

Gypsum boards

They are the prefabricated boards (plaster sandwiched between paper) that are now widely used. One of the problem these boards create is the amount of wasted boards. As the board come in sheet, it has to be cut and a lot of unused waste are piling up into landfill. The paper onto the boards are known to attract mold that contribute to a bad Indoor Air Quality. To fight against this, manufacturers use fungicides and chemicals, which are not desirable environmentally speaking, but needed to avoid the growth of molds.
When using boards, always measure precisely to avoid wastes, specify a high gypsum content, high natural material content, recycled paper sheating or no paper sheating with minimal additives, Low VOC joint compound. Avoid joint compounds with antifreeze, vinyl preservatives, biocides, or that outgas VOCs, avoid chemical additives to wallboards and wasteful drywall purchase or installation method.


Even for plaster it is important to check the ingredients and avoid the potential VOCs out gassing additives. Platers have a high embodied energy, but can be a long lasting solution and participate to the healthy indoor quality of the house. I hope that recycling solutions and habits will come into place soon, especilly for plaster boards.
I personally like Venetian plaster when used in the right setting. They really are beautiful, long lasting, a artwork piece.

Emmanuelle Lemoine


Sustainable Residential interiors - AssociatesIII - Wiley