Building a hearth for a wood-burning stove

Tiles Woodburner Hearth

If you’re installing a wood-burning stove in your home you might also need to install a new hearth for it to sit upon. A hearth must be made from a non-combustible material and protect any combustible materials below. Instances in which you will need to build a new hearth for you stove are:

  • Your property doesn’t currently have a hearth
  • Your property has a hearth but the existing hearth doesn’t comply with building regulations

Building regulations in relation to hearths for wood-burning stoves

There are a few aspects of the building regulations that are relevant to your hearth. These mainly relate to the materials and dimensions of the hearth.

The regulations vary depending on the style of installation. Some can rely on the addition of any non-combustible material of suitable dimensions, while other installations will required a constructional hearth.

Constructional hearth

A constructional hearth is made from a non-combustible material (usually concrete) to protect a combustible floor from the stove. Often it will be sunk to achieve the required thickness (see more details below) at floor level, but it can also be fully or partly above floor level.

Finishing the constructional hearth level with the rest of the floor allows for the addition of a superimposed or decorative hearth on top. The thickness of this superimposed hearth can be included towards the total thickness required in a constructional hearth. The edge of the hearth must be at a different level from the rest of the floor to clearly define a safe perimeter that anyone in the property can see must be kept clear of flammable objects.

Here is a quick rundown of some of the main regulations relating to hearths.

A freestanding stove certified not to heat the hearth to more than 100ºC

  • No constructional hearth is needed
  • Minimum 12mm thick non-combustible hearth placed directly onto the floor.
  • Minimum hearth size of 840mm x 840mm.
  • Minimum gap of 150mm between the stove and the rear and side edges of the hearth.
  • Minimum gap of 225mm (ideally 300mm) between the stove and the front edge of the hearth.

A freestanding stove NOT certified not keep the hearth temperature below 100ºC

  • A constructional hearth is needed.
  • Follow instructions for hearths for fireplace recess installations below.

A stove installation into a fireplace place recess

  • A constructional hearth is needed (unless the stove is certified to not heat the hearth to more than 100ºC, in which case a 12mm hearth is sufficient).
  • Minimum projection into the room of 500mm.
  • Minimum of 150mm wider than the recess at the point it opens into the room.
  • Minimum 250mm thick (or a minimum of 125mm thick if there is then a further 50mm air gap before any combustible materials).

Click here to read the relevant building regulations in full.

MORE: Find out which hearths are suitable for woodburners.

3 thoughts on “Building a hearth for a wood-burning stove

  1. Hi. Im Hetas registered, and had a quick reminder of regs for free standing hearth dimension.. great site.
    My only concern was the hearths for fireplace recess.. I was not aware of any allowance for the hearth if the stove does’nt meet 100 degrees at the feet. Any stove in a chamber is subject to the 125mm minimum thickness and the 500mm projection and 150mm either side of opening. The only time 12mm thickness comes into play is a free standing stove..not one using a chamber..this is my understanding after many chats with Hetas, because people are always trying for an allowance of regs.. and quite a few installers ignore the 500mm rule as many hearths can be undersized for the regulations.

    • Hello, I cannot answer your question however I was wondering if you are willing to answer mine. I have a constructional hearth extending 405mm from the opening recess and only 100mm out either side of the opening. Could I still comply with regulations by overlapping my slate hearth over the constructional hearth and onto the floorboards by the required amounts?

      Thanks,

  2. My stove is inbuilt so my hearth will sit on the floor in front of the stove is there a certain thickness to satisfy building control.

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