Walls are the foundation of a building, especially exterior walls. We will have problems keeping the place intact and safe if they are weak. So the question lingers; why is limestone an excellent exterior wall? Why is it different from the other materials?

We have limestone as one of our top materials for exterior walls because of its:

• versatility in appearance
• strength (it contributes to the mechanical strength of the building)
• resistance to a lot of damaging culprits in construction
• abundance

If you want to know more about what limestone can offer a structure, especially in increasing longevity, we encourage you to read this article.

4 Qualities of Limestone as Exterior Walls

In this article, we included the following types of exterior walls.

Limestone cladding or limestone veneer. Cladding is a non–structural exterior wall that helps protect the structural fence (e.g., load bearing) from damages acquired from external elements.

We do not directly attach it to the wall for a ventilated drainage plane and water-resistive barrier (WRB).

Limestone siding. The siding is likewise a non-structural part of a building that is thinner than cladding and is directly attached to the exterior wall.

Limestone façade. This is for architectural and decorative purposes, making the building look better. Limestone cladding can also be part of the facade.

1. Versatility in Appearance

We are familiar with natural limestone slabs as a strong material for building (more on this later). Still, this stone has been on the list of the best-chosen material for external walls because of its spectacular beauty.

Colors

Let us start with the color. The color outcome of limestone depends on the minerals and other impurities present during its formation.

For example, aside from the dominant mineral calcite (CaCO3), which is a mineral form of calcium carbonate, there are also:

• dolomite
• quartz
• feldspar
• sand
• clay

Our limestone slabs come out as earthy colors that are soft and subtle (even the dark palette). Pulycort, a stone producer like us, provided a list of the colors of limestone.

Check this table out to pick a preference for your external wall, either cladding, siding, or façade.

COLOR	VARIATIONS
White Limestone	Bianco Perlino(creamy white or off-white)
Beige Limestone	Moca Cream(uniform beige)
Grey Limestone	Azul Valverde(a gray background that is quite consistent and has a touch of brown)
Black Limestone	Ebano Black(black background with white or pink streaks)

Finish

Our factory has the equipment to perform any finish. But for external walls, we advise our clients to choose between honed and tumbled limestone finish because these are the most practical stones we can use outdoors.

• Honed Finish. The surface will be smooth, even, and matte. This is also the step before polishing a limestone slab.
• Tumbled Finish. The slab’s texture will be rough but still has a uniform appearance overall. It will provide a very natural and antique external wall.

2. Strength

Out of the three external walls that we mentioned (cladding, siding, and facade), cladding is the one that contributes to the mechanical strength of the building’s actual walls.

Mechanical strength in construction is the overall capability of the material to carry a load without crumbling and bending. It is also the strength that defines a material’s capacity to withstand external forces potentially damaging, such as the weather.

So instead of these damaging factors harming the structure’s walls, the limestone cladding acts as a shield.

In this section, we will explain the mechanical properties of limestone wall cladding. While sidings and façades are also durable (more on this later), they do not contribute to the general strength of the structure.

a. Compressive Strength

This property defines the capacity of a specific material to hold weight or bear load before it starts showing signs of rupture. In stones, the standard for construction is 100 newtons per square millimeter (N/mm2) to ensure capacity.

While our limestone cladding will not carry any weight as they are non-structural, it is essential to know how vital this natural stone can be.

If you have read our previous articles, we always mention that in Sinodec, our limestone slabs—no matter the style or color—have at least 180 N/mm2. They undergo rigorous quality checking so our clients’ projects can be safe and lasting.

b. Tensile Strength

It determines the amount of stress the natural stone can handle before showing signs of stretching or breakage. This is one of the contributors to a material’s resistance to cracks, and limestone is known for the said quality.

The standard measurement for the construction material’s tensile strength—in concrete, for example—is 300 to 700 pounds per square inch (psi). Limestone has a measurement of 725 to 3 630 psi.

c. Flexural Strength

Also called transverse strength is the bending strength of a material or the amount of stress it can take until it breaks because of bending.

Don’t worry; we will not bend our limestone cladding in half. However, the measurement is 435 to 5220 psi.

d. Mohs Scale of Hardness

This scale measures the hardness of a stone which also affects its resistance to scratches.

Limestone is a soft stone that has a measurement of 3.5 on the Mohs scale. Remember that “soft” doesn’t mean less quality; in reality, this contributes to the ease of designing, such as carving, detailing, and sculpting.

3. Resistance to Damage

We have already discovered that a limestone exterior wall, such as cladding, helps improve the mechanical strength of a structure. In this section, we are going to explain the “how.”

You might also want to visit an article about limestone as a good cladding stone if you are specifically looking for quality cladding.

Weather and Temperature

What commonly damages a structure are natural elements like:

• heat
• cold
• wind
• snow
• rain

Limestone exterior walls are impervious to these elements, especially heat, as they can handle up to 300 degrees celsius before they start cracking. We are sure that no building will be subject to such temperature.

With the cold, snow, and rain, limestone can tolerate the moisture as long as we also do regular maintenance, such as cleaning or shoveling snow away from the wall.

Ultraviolet (UV) Rays

UV rays are notorious for fading marble, but this is not the case with limestone; we don’t have to worry about placing it outdoors.

We have seen and led limestone wall cladding, siding, and façade projects, which are still strong even with minimal maintenance requirements.

4. Abundance

Although this will depend on the following:

• quarry of the type of limestone and;
• availability in the market

Limestone is still more affordable than other natural stones because of its abundance. Although, we still have to be careful in selecting quality limestone slabs.

One of its largest exporters in the world is China, whose exports amounted to $3.32 million in 2020. Our factory itself continues to provide sturdy, strong, and beautiful limestones to different countries abroad, scarce ones.

Can We Use a Travertine for Exterior Walls?

Travertine is a type of limestone formed on the land, unlike the usual kinds made by marine life.

We can also use this stone for our exterior walls since it provides a variety of soft colors and it has impressive durability, which includes crack resistance.

Conclusion

Non-structural exterior walls such as cladding, siding, and façade should be appearance-wise and durable. This is why limestone is an excellent outer wall material with consideration to availability.

Aside from having aesthetic color and finishing choices, limestone wall cladding, in particular, strengthens the mechanical properties of the building that also contributes to the structure’s lifespan.

Do you have an ongoing exterior wall project for your place? Let us know in the comments which type of limestone or material you have chosen and why.