How To Stucco

In order to understand how to stucco, it’s important to gain a good understanding of the stucco structures and the reason why it has been successfully used for so many years in residential and commercial construction.

The term ‘Stucco’ is used to describe a type of exterior plaster applied as a two or three part coating directly onto masonry, or applied over wood and metal lath.

Traditional, or three-coat stucco, which is often also referred to as conventional stucco, is known as three-coat because it’s installed in three separate layers. Stucco is applied directly, without lath, to masonry substrates such as brick, stone, concrete or hollow tile. On wood structures, stucco, like its interior counterpart plasters, must be applied over lath in order to obtain adequate properties to enhance adherence to the wall.

If installed over a wood frame structures, stucco may be applied to wood or metal lath nailed directly to the wood frame. It may also be placed on lath that has been attached to furring strips. The furring strips are laid over building paper covering the wood sheathing.

The Stucco system starts with a simple drainage plain based on building paper over framing members of a structure. Building codes call for two layers of Grade D building paper, which consists of virgin wood fiber, saturated with tar. This paper serves to drain water and protect the wood frame against condensation and moisture caused by the difference of outside/inside temperature. The paper and flashing has to overlap each other in a way that creates a solid shingle effect. Over the paper and flashing, metal lath is attached to the wall with wad nails and/or staples. Metal lath serves the crucial purpose of holding the cement base coat in place.

With conventional stucco, the base coat is comprised of a 3/8-inch initial application, referred to as a scratch coat and a second 3/8-inch application known as a brown coat. The finish or color coat is a thinner application of only approximately 1/8-inch making a total system thickness of about 1 inch, including the paper and lath. The plasters system itself equates to only 7/8-inch. This is basically how to stucco in the conventional format.