why do they put rocks on roofs

2 min read 06-12-2024

Roofs are essential for protecting homes and buildings from the elements. But sometimes, you see more than just shingles or tiles up there. Why do they put rocks on roofs? The answer isn't as simple as you might think. It depends on the type of rock, the style of roofing, and the overall purpose. This article explores the various reasons why rocks might be found on a roof.

Different Types of "Rocks" on Roofs

The term "rocks" is quite broad. What might appear as rocks on a roof can actually encompass several different materials and applications:

1. Gravel Roofing: The Classic Application

This is the most common reason you'll see rocks on a roof. Gravel roofs, typically found on flat or low-sloped roofs, utilize small, smooth stones spread over a layer of roofing felt. This method is particularly popular for:

Protection: The gravel protects the underlying membrane from the sun's UV rays, preventing degradation and extending the roof's lifespan. It also provides a layer of protection against impacts from debris.
Ballast: The weight of the gravel acts as ballast, holding the roofing membrane in place, especially important in windy conditions. It prevents the membrane from lifting or being damaged by wind uplift.
Waterproofing: The gravel layer helps to prevent water ponding, which can cause damage to the roof membrane.

2. Decorative Stone: Aesthetic Appeal

In some cases, rocks are used purely for aesthetic purposes. Larger, more decorative stones might be incorporated into roof designs for a unique architectural look. This is more common with custom-built homes or buildings aiming for a specific design style. Think of it as landscaping, but for the roof.

3. Rock-Covered Tiles: A Blend of Form and Function

Some roofing tiles, particularly in certain architectural styles, are designed with a textured surface that resembles rock. These tiles offer both the aesthetic appeal of rock and the protective qualities of traditional roofing materials. They are often made from concrete or clay.

4. Accidental Debris: Not Intentional

Finally, it's worth noting that rocks can sometimes end up on roofs accidentally. Strong winds can carry debris, including stones, onto a roof. This isn't a planned application, but it can still be found on roofs occasionally.

Choosing the Right Roofing Material: Factors to Consider

The choice of roofing material, including whether to use gravel or other materials, depends on several factors:

Climate: Areas with extreme weather conditions might benefit from a more robust roofing system, like a gravel roof.
Building Style: The overall architectural style of the building will influence the suitability of different roofing options.
Budget: Different roofing materials come with varying costs.
Maintenance: Some roofing systems require more maintenance than others.

Conclusion: Beyond Just "Rocks"

While the term "rocks on roofs" might seem simple, it encompasses a variety of materials and applications. From the functional protection of gravel on flat roofs to the aesthetic appeal of decorative stones on sloped roofs, the use of rocks in roofing is diverse. Understanding the reasons behind this practice provides a deeper appreciation for the intricate design and construction of buildings. Next time you see a roof with what appears to be "rocks," consider the broader context and the various roles these materials might play.