Natural Slate vs Man-Made Roofing: Carbon, Cost and What Comes Next

This piece was originally written to highlight the embodied carbon differences between common roof coverings. However, in light of recent geopolitical and economic developments, it feels appropriate to take a slightly broader view, particularly following our recent note on the situation in Iran.

It seems that nearly all acquisition teams within the construction industry are being hit by another round of price increases, with manufacturers and suppliers citing rising oil prices as the primary cause. An all-too-common phenomenon in the post-COVID world we now operate in.

Carbon is no longer just an environmental consideration; it is increasingly becoming a cost consideration as well. Carbon, energy and cost are now directly linked.

Across the construction supply chain, CO₂ production is fundamentally tied to energy use. And energy, particularly in heavy industry, is still heavily dependent on fossil fuels.

Concrete, clay and fibre cement products all rely on energy-intensive manufacturing processes, high temperature kilns, cement production, and continuous plant operation. These processes consume large volumes of fuel, most of which is oil or gas derived.

As a result, their costs are heavily influenced by:

• Rising oil and gas prices 
• Increasing environmental charges 
• Fluctuations in energy supply

We’re now in a market where energy costs are unlikely to come down any time soon. If anything, they’re more likely to keep rising.

Slate however is a product formed naturally over millions of years. Once quarried, it requires relatively minimal processing, no firing, and no chemical transformation. As a result, the energy input associated with production is significantly lower. Put simply, it is a material that is extracted and prepared, rather than manufactured.

And that leads to a simple but important point: The higher the CO₂ footprint of a product, the more exposed it is to future price increases.

Estimated CO₂ Emissions from Roofing Materials (Production Only)

The table below sets out indicative embodied carbon associated with the production phase only of each material. This includes raw material extraction and manufacturing, but excludes transport, installation, maintenance, and end-of-life impacts.

Explanation & Assumptions – To provide a consistent comparison, typical industry weight ranges per m² have been combined with widely referenced carbon intensity data (kg CO₂ per tonne) from published lifecycle assessments and environmental datasets. These have then been converted into CO₂ per m² basis, which reflects how roofing materials are specified in practice. These figures represent a global, averaged view, rather than product-specific Environmental Product Declarations (EPDs). Actual emissions will vary depending on: manufacturing processes, energy sources and fuel mix, plant efficiency and geographic location. While every effort has been made to ensure the ranges are realistic and representative of current industry understanding, they should be considered indicative rather than absolute.

Based on the figures above, clay tiles can have significantly higher associated CO₂ production, potentially up to 12x that of natural slate, per m². In simple terms, slate is less reliant on the most variable part of the cost equation, fuel.

Historically, these differences have been discussed in environmental terms. Increasingly, they are becoming financial.

If energy costs continue to rise, and if carbon regulation tightens, then:

High energy, high CO₂ products will see the greatest upward increases in pricing. Alternatively, lower energy, low CO₂ materials will remain more stable

A Practical Specification Choice

For architects, contractors and merchants, slate is a material that:

• Supports sustainability considerations
• Is less affected by energy-related price changes
• Has a longer typical lifespan than many alternatives
• Offers a cost-effective and visually appealing roof covering
• Sits comfortably within more environmentally conscious choices

Summary

Slate prices, of course, are not immune to rising oil costs and they are being affected by these increases, however they should be to a lesser extent. Overall, slate remains one of the most balanced roofing solutions available, both environmentally and commercially.

If you would like to discuss specifications, pricing, or upcoming projects, please call 01752 84 80 80 or contact us.