How to Measure for a Bespoke Fireplace Hearth

How to Measure for a Bespoke Fireplace Hearth

A well-fitted hearth is essential for both safety and appearance, especially when you're installing a log burner or open fire. Whether your fireplace is aesthetic or active, measuring accurately is critical to ensure the hearth complies with UK building regulations and fits the design of your home.

At Dream Stone Store, we craft each hearth to order—cut precisely from natural stone like riven slate, honed slate, granite, or marble. This guide covers how to measure your hearth correctly and what rules apply when it's being used with a working appliance.

What Is a Hearth?

The hearth is the base platform that sits beneath a stove or open fire. It can be rectangular, T-shaped, quarter circle, or any custom form required. It not only adds style and contrast but also protects the surrounding flooring from heat and stray embers.

Measuring Your Hearth – Step by Step

Use a tape measure and note the following dimensions clearly. All measurements should be in millimetres for accuracy.

1. Overall Width

The total width from left to right across the front of the hearth.
Tip: It should extend beyond the fireplace opening or stove to ensure symmetry and compliance.

2. Projection (Depth)

The distance from the back wall (or chimney breast) to the front edge of the hearth.

3. Rear Width

If your hearth has a T-shape or a narrower rear section, this is the measurement of the rear segment.

4. Internal Cut-Outs or Returns

For hearths that wrap around raised fire chambers or brick recesses, make sure to measure each internal return or notch precisely.

UK Hearth Regulations for Active Fireplaces & Log Burners

If your hearth is being used with an active stove or open fire, the following minimums apply under UK building regulations:

  • 300mm projection in front of the stove or heat source

  • 150mm width on each side of the stove (minimum)

  • 12mm thickness minimum IF the stove doesn’t exceed 100°C at the base

  • For durability and practicality, we recommend a minimum thickness of 20mm, particularly for stone like slate or granite

Important:
If the stove exceeds 100°C at the base, the hearth must be constructed from a minimum 250mm thick constructional hearth, which may include a sub-base and a decorative top layer.

We focus on fabricating the decorative stone hearth only, not structural sub-bases.

Hearth Shape Examples We Offer

  • Rectangular Hearths – For simple, flat designs

  • T-Shaped Hearths – Common for recesses with protruding legs

  • Quarter Circle Hearths – For corner installations

  • Tear Drop / Pentagon – Ideal for freestanding stoves in the room

  • Split Hearths (Two-Piece) – Easier for access and larger formats

Additional Tips for Measuring

  • Always double check your dimensions before uploading.

  • Use masking tape or cardboard templates on the floor to visualise your hearth.

  • If unsure, sketch your layout by hand and upload a photo on the product page—we’ll help verify it.

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