How big does a hearth need to be for a log burner?

The visible hearth should reach at least 225 mm in front of the stove and 150 mm each side. A free-standing stove on a full constructional hearth needs at least 840 mm by 840 mm.

Can I put a log burner on a wooden floor?

Only on a proper hearth. If the stove keeps the floor below 100°C, a 12 mm non-combustible plate is enough; otherwise a 125 mm constructional hearth is needed.

Is a glass hearth safe?

Yes, if it is toughened glass at least 12 mm thick and the stove is approved for a 12 mm hearth. It must still be big enough to meet the distances.

How much does a slate hearth cost?

A ready-made slate plate is typically £150 to £400. Bespoke sizes and thicker stone cost more.

Do I need a hearth for a stove on legs?

Yes. Legs lift the stove but the floor in front still needs protecting from embers when the door opens.

Hearths for log burners

Every stove sits on a hearth, and the size and thickness are set by Building Regulations rather than taste. The hearth stops heat and falling embers reaching the floor, and marks out the space where nothing that burns should be. A ready-made glass, slate or granite plate usually costs £150 to £400; a built hearth with wall protection is more like £300 to £1,000.

From about £150 to £400 for a ready-made plate

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Typical UK prices including VAT, checked November 2026.

Which hearth you need

A thin plate on a normal floor. If the stove maker says the floor beneath will stay below 100°C, a 12 mm non-combustible plate on top of the floor is enough.
A full constructional hearth. If the stove can heat the floor above 100°C, it needs a solid hearth at least 125 mm thick, usually 840 mm square or more.
A superimposed hearth on top. The decorative top layer of slate, stone or glass that sits on the constructional hearth and shows the safe zone.
Wall protection behind. If the stove is close to a wall that can burn, such as plasterboard on studs, a non-combustible shield or the stove maker’s clearances apply.

What a hearth costs

Item	What it covers	Typical cost
Ready-made hearth plate	Glass, slate or granite, 12 mm or thicker, supplied	£150 to £400
Built hearth	Constructional hearth with a stone or slate top, wall protection	£300 to £1,000
Stove fitting with liner	If the hearth is part of a full installation	£1,000 to £1,700

Typical UK ranges including VAT, from national price guides read November 2026. Estimate your own job.

Planning a hearth around a stove you have chosen? A fitter can confirm the sizes for that model.

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The hearth rules in plain words

Approved Document J covers hearths for solid fuel stoves in England and Wales. The details are in the diagrams, but the main points are short.

Constructional hearths

Where a stove could heat the floor beneath it above 100°C, it must stand on a constructional hearth: solid, non-combustible material such as concrete or masonry at least 125 mm thick, including any decorative surface. In a fireplace recess the hearth runs back into the recess and projects into the room; a free-standing stove needs one at least 840 mm by 840 mm.

The 12 mm plate

Most modern stoves are tested so that the floor beneath stays cooler than 100°C. For these, Part J accepts a hearth of non-combustible board or sheet material, or tiles, at least 12 mm thick. That is why a glass or slate plate is all many installations need, and why the stove maker’s instructions matter. If they say a constructional hearth is required, it is.

The space in front of the stove

The superimposed hearth (the visible top) should extend at least 225 mm in front of the stove door, and at least 150 mm to each side, with a little more in front if the stove can be used with its door open. The edge should be clearly marked, for example by a change in level or material, so furniture and rugs stay off it.

Walls beside and behind

Stoves list a minimum distance to combustible material. Brick, stone and block walls are fine. Timber-framed or stud walls lined with plasterboard count as combustible, and a stove close to one needs a non-combustible shield with an air gap behind it, or a bigger distance.

Choosing a material

Toughened glass is popular because it is thin and lets the floor show through; it needs a polished edge and can scratch. Slate and granite are hard-wearing and suit most rooms. Limestone and sandstone look soft and warm but can stain. Whatever you choose, it must be wide enough for the rules above with the stove you have chosen, so pick the stove first.

Sources we used

Prices are typical ranges from national UK price guides for homeowners, read November 2026, including VAT. Rules are summarised in our own words as general information.

How it gets done

A hearth is usually fitted on the same visit as the stove. A built hearth may need a day for the base to cure.

Check the stove
Its instructions set whether a 12 mm plate or a full hearth is needed.
Measure the zone
225 mm in front, 150 mm each side, and the distance to the walls.
Lay the base
A level, non-combustible base, or the old hearth repaired.
Fit the top
Glass, slate or stone laid level with a clear edge.

Common questions about stoves

How big does a hearth need to be for a log burner?: The visible hearth should reach at least 225 mm in front of the stove and 150 mm each side. A free-standing stove on a full constructional hearth needs at least 840 mm by 840 mm.
Can I put a log burner on a wooden floor?: Only on a proper hearth. If the stove keeps the floor below 100°C, a 12 mm non-combustible plate is enough; otherwise a 125 mm constructional hearth is needed.
Is a glass hearth safe?: Yes, if it is toughened glass at least 12 mm thick and the stove is approved for a 12 mm hearth. It must still be big enough to meet the distances.
How much does a slate hearth cost?: A ready-made slate plate is typically £150 to £400. Bespoke sizes and thicker stone cost more.
Do I need a hearth for a stove on legs?: Yes. Legs lift the stove but the floor in front still needs protecting from embers when the door opens.

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Start with a postcode. A few details about the room and the chimney (or the lack of one) let a fitter give you a sensible first figure before they visit.

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