Thermal Bluestone vs. Natural Cleft: Difference, Pros, & Cons

Bluestone is one of the best materials available for outdoor living projects. It’s timeless, sturdy, and inviting all at once. And, thanks to its different finishes, it offers versatility like no other. But for many homeowners, that diversity is overwhelming.

So today, we’re going to focus on the two most popular options. As Stamford’s No. 1 patio contractors, we’ve already pitted thermal bluestone vs. natural cleft, and we’re ready to show our findings. Continue reading to understand the pros and cons of each finish, as well as their main differences.

What Is Bluestone?

Bluestone is a dense natural stone commonly used for patios, walkways, steps, pool decks, garden paths, and other outdoor living areas. While it usually comes in blue-gray tones, it also offers various shades like brown, tan, green, rust, lilac, and charcoal.

We often recommend working with bluestone because it balances strength and style. It handles foot traffic, changing weather, and everyday outdoor use while giving a patio or walkway a stunning appearance.

To achieve that unmatched aesthetic, this natural sandstone provides a wide range of finishes. That’s where natural cleft and thermal come in. They are among the most common bluestone finishes, but due to the fabrication process, each creates different textures, thicknesses, and design effects.

What Is Natural Cleft Bluestone?

Natural cleft stone splits along its natural layers. This process creates an organic surface with subtle ridges, dips, and texture. Therefore, instead of a perfectly smooth finish, each piece carries its own character.

Natural cleft finish works beautifully for traditional patios, garden walkways, older homes, and landscapes that need a natural look. It pairs well with stone walls, planting beds, brick details, and classic New England architecture.

Pros of Natural Cleft Bluestone

• Provides strong visual character with a natural, earthy appearance.
• Offers good traction due to its textured surface.
• Hides dirt, dust, and minor wear better than smoother finishes.
• Each piece is unique, creating a custom patio or walkway.
• Complements traditional homes and garden landscapes.

Cons of Natural Cleft Bluestone

• The uneven surface makes furniture placement more difficult.
• Chairs and tables may wobble if not carefully installed.
• Thickness can vary, requiring skilled installation and leveling.
• May not suit modern designs that call for a uniform finish.

What Is Thermal Bluestone?

Thermal bluestone, also called flamed bluestone, gets cut and treated with intense heat. That heat changes the surface texture and creates a more consistent, lightly rough finish. The result feels smoother than natural cleft but still works well for outdoor walking surfaces.

A thermal finish often suits modern patios, pool areas, outdoor dining spaces, walkways, steps, and commercial-style entrances. Its clean look helps create crisp lines and a contemporary design.

Pros of Thermal Bluestone

• Provides a uniform, smooth surface ideal for placing furniture and creating clean patio lines.
• Delivers a refined, polished appearance while maintaining natural stone appeal.
• Offers dependable traction due to the heat-treated surface.
• Allows for tighter joints and a more organized layout, thanks to consistent thickness and sizing.
• Enhances patios, walkways, and pool decks with an elegant, structured look.

Cons of Thermal Bluestone

• Typically costs more than natural cleft due to additional cutting and finishing processes.
• May appear less natural because of the manufactured surface.
• Can show dirt, scuffs, and wear more easily than textured stone.
• May feel too formal for rustic landscapes or traditional home styles.

Thermal vs. Natural Cleft Bluestone: Key Differences

Texture

Natural cleft bluestone has a rougher, layered texture created by splitting the stone along natural seams. Thermal bluestone, on the other hand, has a smoother, more consistent texture created through cutting and heat treatment.

Appearance

Natural cleft bluestone creates a rustic, traditional, and earthy look. It works well with garden paths, classic patios, and natural landscapes. Thermal bluestone creates a cleaner, more refined look. It suits modern patios, pool decks, formal walkways, and outdoor kitchens.

Thickness and Installation

Natural cleft pieces can vary in thickness, so installers must level each stone carefully. Thermal bluestone usually offers more consistent sizing, which can help create cleaner joints and a flatter finished surface. Both options require proper excavation, base preparation, drainage, and joint work for lasting results.

Slip Resistance

Both finishes can work well outdoors when installed correctly. Natural cleft bluestone provides traction through its naturally textured surface. Thermal bluestone gains traction through the flaming process, which keeps the surface from feeling overly slick.

Which Bluestone Finish Should You Choose?

We’ve settled on the fact that Pennsylvania bluestone is simply a wonderful material for outdoor spaces, whether in the form of pavers or larger slabs. And that each finish offers unique benefits and drawbacks. But how can you even choose between the two?

Here’s the truth: choose natural cleft bluestone if you’re looking for a classic aesthetic with texture, variation, and old-world charm. However, if you’re not into the irregular bluestone look and prefer cleaner lines, a flatter surface, and a modern appearance, thermal finish is the winner.

If the choice still comes down to a close call, consider your home’s architecture, maintenance expectations, budget, and daily use.