How Does Stucco Hold Up Against Fire?

Stucco is one of the most popular home exterior materials in the country. When installed properly, stucco can protect your home against a wide variety of damage, including water, pests, blunt impacts, high and low temperatures, and even fire.

But, how good is stucco at protecting your home and its inhabitants from the destructive nature of fire? How does stucco compare to other materials frequently used for the walls of homes? And What is the fire rating of a properly installed stucco system?

This article will answer all those questions and more, to give you an accurate account of the protective qualities stucco offers.

Fire Resistance of Stucco

Stucco and stone

Stucco is a highly fire-resistant building material primarily due to the ingredients that make it up. These ingredients are portland cement, sand, limestone, water, and other additives. None of these ingredients are flammable or combustible, which leads to the same being true for stucco as a whole.

The way in which stucco is applied to walls also helps with preventing the spread of fire. It’s installed in multiple layers, with three layers being the most common. These layers provide added thickness and therefore protection to the surface of the wall.

In addition to the fire-resistant qualities stucco has itself, the material can also be used to cover other fire-resistant building materials, as well. While stucco is most commonly used on stick-built (wood frame) homes, it can also cover stone or brick. This is most frequently done when the stucco aesthetic is desired.

Comparison to Other Siding Materials

How does stucco stack up against other common siding material options in the fire-resistance department?

Compared to vinyl, wood, and manufactured wood, stucco is far more fire-resistant. Vinyl quickly and easily melts when exposed to the high temperatures associated with fire. In fact, Vinyl can even begin to melt when exposed to direct, concentrated sunlight on a hot day.

Wood and manufactured wood, meanwhile, are highly combustible and don’t provide any fire protection. While vinyl won’t protect your home from fire, at least it won’t spread the fire. The same can’t be said about wood-based siding.

Stucco is most comparable to James Hardie fiber cement siding and both stone and brick veneer. All of these siding options offer good protection against fire. The primary vulnerabilities of these materials are cracks. If there are cracks in the surface, the fire will be able to reach the wooden interior of the wall faster.

The most fire-resistant building materials are stone, brick, and metal. The difference between stone and brick and their veneer counterparts is that they are full-thickness and thus offer far more protection.

Stucco Fire Rating

The standard thickness of a stucco installation is 1-inch. To reach this thickness, there will be at least 3 layers of stucco applied to the wall. These are the scratch, brown, and finish coats. While these 3 layers are the norm, additional layers are also possible, usually to protect against specific, known environmental hazards in the region.

At 1-inch thick, stucco generally has a fire rating of 1 hour. This means that if the wall was to be exposed to flames, it would take 1 hour for the fire to breach the wall and damage the rest of your home.

1 hour is a remarkably long time to resist fire when compared to the average time for both modern and historic homes. The average time for a fire to breach the walls of a modern home is between 3 and 5 minutes. Homes built 30 years ago are able to last between 15 and 17 minutes, on average.

Stucco’s 1-hour fire rating is significant for two reasons. First, it means that you and your family have more time to escape from the building in the event of a fire. And second, it means that your home can hold out until the fire department shows up to combat the blaze.

Protect Your Home From Fire

Stucco and siding

If fire resistance is a quality you’re looking for in your home’s siding, stucco is a great option. As a mixture of non-combustible materials, stucco is able to withstand high temperatures and exposure to flames without igniting.

While vinyl siding may be the most widely used and inexpensive option, it also offers far less protection than stucco. On the other end of the scale, stone and brick offer the most protection, while also being more expensive options. Stucco falls in the middle along with stone and brick veneers, offering protection at a reasonable cost.

The protection offered by stucco comes in the form of a 1-hour fire rating, meaning it will take fire 1 hour to breach the wall on average. This is a far greater fire rating than most new homes have.

However, even with all of stucco’s fire protection, it’s important to remember that most house fires start from within the home. Stucco can’t protect your home from those fires. But it can protect it from fires originating outside your home.

Stucco Today

Stucco Today is your local stucco exterior installer. We have been in the stucco business since 1989 and have built a reputation for honest and reliable work. Contact us today for a free quote for your next stucco project.