Hearth Regulations

The Building Regulations concerning hearths can be an area of confusion for some with the different thicknesses required for combustible or non-combustible floors and terms such as constructional and superimposed. By breaking these regulations down to what is relevant to you, we hope this simple guide clears the mystery surrounding hearths.

So, what is the purpose of a hearth? It is basically a clearly defined protective area around and under your stove to prevent it setting fire to the fabric of your home and furnishings and to prevent people getting accidentally burnt. For obvious reasons it is constructed from a non-combustible material and must be of suitable dimensions (as dictated by the Building Regulations) to catch any hot ash or sparks that may escape from the fire.

Constructional Hearth

Traditionally, stoves are installed in existing fireplaces and therefore sit on what is known as a constructional hearth. The term constructional simply means it is built into the floor or is part of the construction of the building. This is probably the most common place hearth in UK homes and there are three measurements to consider:

  • At least 150mm (6”) of hearth either side of the stove
  • At least 300mm (12”) of hearth in front of the stove
  • If the floor is combustible then the hearth must be at least 250mm* (10”) deep OR this can be reduced to 125mm (5”) deep if you have an air space or air gap of 50mm underneath

*The measurement of 250mm may seem big however, bear in mind this is a constructional hearth and so some of this is built down into the structure of the floor.

Hearth Depths

Cool Hearth rated These are the exception to the rule. Some modern stoves do not exceed 100oC at their base and have received a cool hearth rating. These are the only models of stove suitable for 12mm superimposed hearths which are manufactured from glass or slate for their decorative as well as protective qualities.

Glass Hearth TearGlass Hearth CircleGlass Hearth CurvedGlass Hearth Semi

Free Standing Hearth Contemporary convection stoves can be positioned anywhere in the room but still require a hearth. These tend to be of the superimposed variety but the regulation here is they must measure at least 840mm by 840mm. Please click here to view our Hearths.

Hearth Widths

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15 thoughts on “Hearth Regulations”

  1. Hi
    Can you tell me if the Oylmpus 10kw requires a constructional hearth or is it ok just with 25mm decorative hearth ?

    1. Thanks very much for your enquiry. I have passed this on to our Customer Services Team who will respond to you directly.

  2. Hi, i am looking at getting a fre standing stove. It is rated so i can use a 12mm hearth. Does the hearth need to be 840 x 840 or just 150mm each side as i have been told different things. Thank you

  3. I want a double fronted open fire, the fire cradle is 55cm x 25cm the hearth will be 90cm wide and 90 cm deep. It will sit upon a brick construction (3 bricks high). The cradle will sit exactly in the middle.

    What thickness hearth would I require please?

    1. Regretably, as we primarily deal with closed heating appliances and their requirements, this is not something that we would be able to answer. I feel your best option for the most accurate advice would be to contact info@hetas.co.ukhttp://www.hetas.co.uk and they should be able to provide the answers to your questions.

  4. I was looking to purchase the FLAVEL ARUNDEL 4.9KW DEFRA MULTIFUEL STOVE but don’t know what Hearth I need to build for it? Works are underway on my house and tiles are ready (obviously will use fireproof cement!) but it’s a Victorian house with a shallow fireplace void and original wooden flooring. I know I need to raise up from floor level before tiling, but unsure how much.

    Thank you!

    1. A stove such as the incredibly popular Flavel Arundel has not been ‘Cool Hearth rated’ meaning it must be sited on the traditional full-depth hearth (known as a constructional hearth) as opposed to a decorative 12mm hearth (such as only glass or slate for example). We have an article explaining the regulations surrounding hearths (https://www.glowing-embers.co.uk/blog/hearth-regulations/) but basically it can be 125mm deep only if there is a 50mm air gap beneath that. Otherwise, it must be 250mm full depth.

  5. Thank you so much for the swift reply!

    Ideally we’d just raise up from wooden floor and then use heatproof cement to apply the zellige tiles we plan to use. We do not need a very big stove at all, and our fireplace void is quite shallow, so the stove will project into the room. Do you have a stove you sell and that you would recommend that may fit, and be able to sit on such a hearth? (We live in Zone 2, London).

    Thanks again,


  6. Hi, Im looking at your smaller sized log burners, however will need to get a new hearth. Am I able to install a hearth so thats its flush with the flooring? My floor is wooden floorboards with a wood tiles.


    1. Unfortunately you would be (or should be) unable to install a hearth that is flush with the floor as besides from being a non-combustible plate for your burner to sit on, one of the primary purposes of the hearth is to designate a clear, raised, safe area around the burner.

  7. Hi, I have read your blog and am more confused, can you help please? I am looking to buy either a Loft or Huntington balanced flue gas stove. Your site says I need to install a 5″ thick hearth underneath. Another stockist told me its 2.5″ and another stockist told me I don’t need to have one at all. So who is right? Thanks in advance.

    1. The hearth regulations within this article are concerned with solid fuel stoves only which burn at far higher temperatures than gas stoves. For the regulations concerning installing gas burners, please seek the advice of a Gas Safe registered engineer.

  8. Hello,
    This may sound silly but we urgently need a new fireplace as we are not able to replace our bricks inside the fire box as they don’t make them anymore. Our hearth is raised about 20cm off the ground, it currently does not fit with any fireplace out there to be acceptable with the measurements most fireplaces need from the door to the edge of the hearth. My question is, are we able to get a steel floor tile to screw down into the floor below the current hearth but flush up hard against it to get to the acceptable measurements to fit a new fireplace? Or do we need to take the current one out to put a new one in?
    Thank you

    1. Hard to say I’m afraid as in theory that would work as you are extending a non-combustible base to the required distance in front of a bunrer but there are depths that need to be considered also, which are probably more important than the forward distance. I would strongly advise asking a local HETAS installer to conduct a survey at your property who will be able to answer this and any other questions you may have. I will advise however, moving forward, opting for a cool hearth rated stove if the size of the hearth may cause an issue. You can then sit the stove on a decorative hearth. Options we stock are glass, granite or sandstone https://www.glowing-embers.co.uk/fireplaces/hearths

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