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non-combustibility and fire-resistance

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New material for heat radiant fireplace enclosure

Grenatherm board - reliable heat radiant fireplace enclosure recommended by stove experts

Radiant construction boards developed as an alternative to conventional and storage heater enclosures

Properties of Grenatherm boards

Properties of Grenatherm boards

Grenatherm heat radiant construction boards are made of expanded vermiculite and an inorganic binder that accelerates heat transfer through the material. In addition to the special binder composition, the heat radiant effect of the boards is achieved by a higher density of 750 kg / m3.

There is no danger of shape changes or fumes during high temperature heating or firing. It is a feature of Grenatherm that the board transmitted healthy radiant heat, has high strength and can be machined with standard hand-held woodworking tools. These properties have not changed over the years and there is no degradation of the board.

The Grenatherm board allows you to construct a reliable and radiant fireplace mantel easily and economically within one day which was not possible until recently.

Reaction to fire according to ČSN EN 13501-1: A1 - non-combustible

Why the radiant hot-air fireplace?

Why the radiant hot-air fireplace?

In the first phase of heating the radiant hot-air fireplace heats the air in a classical way. Via grids it provides heat to the room. After warming the Grenatherm, the fireplace starts transmitting thermal energy by radiation through its sheathing. The ratio of transmitting the thermal power of the fireplace is therefore divided between the conventional air heating (via grids) and thermal radiation.

By various technological procedures of construction and the right choice of a fireplace insert it is possible to also reach the accumulative properties of a fireplace. The accumulative properties of fireplaces start being necessary thanks to the lower energy intensity of buildings. You will achieve a distribution of thermal power.

Advantages of radiant heat

  • Radiant heat is healthy, natural and pleasant for man. 
  • As well as the Sun it warms the surrounding area by electromagnetic radiation. This radiant heats objects, walls, people but does not heat the air between them directly. 
  • Thus the radiant heat is not possible to ventilate. 
  • Radiant materials drain the thermal energy from the hot-air fireplace which mitigates the risk of overburning the air. 
  • The radiant hot-air fireplace also reduces air drying in the heated building and temperature differences in the heated area.
When to choose Grenatherm boards

When to choose Grenatherm boards

You can use Grenatherm boards in the construction of hot-air fireplaces, where radiant heat is required and the heating capacity of the heater is not required. With the correct sizing and technical design, you will achieve the required heating of the heater within 60 minutes after heating up.

They can also be used in accumulation systems, eg for enclosures with built-in accumulation and fireplace insert or for enclosures with built-in accumulation and fireplace insert with accumulation set.

Grenatherm is a suitable choice for customers who need radiant heat as quickly as possible, do not want to wait for heating of accumulation materials and their main requirement is fast production at an affordable price. You will appreciated Grenatherm boards even in cases where it is necessary to make the enclosure in areas where high dustiness cannot occur (eg in already furnished interiors).

Machining and processing Grenatherm

Machining and processing Grenatherm

Grenatherm vermiculite boards are easily machined with conventional woodworking tools. When working with them, there is minimal dust. No protective gloves are required to handle the boards.

Depending on the conditions and requirements for the final functionality of the installation, the boards can be combined with Grenaisol and Grenalight boards.

The application of mortars and plasters is very fast and simple due to the high adhesion of the board surface. Primer is not required before the final surface finish.

We recommend using our proven Grenacoat system for final finishes. Achieve great results with it.

Advantages of Grenatherm boards

Advantages of Grenatherm boards

  • Simple and economical solution 
  • Building and heat radiant element in one 
  • Stable and high quality materiál 
  • Easy machinning 
  • Simple machining with conventional woodworking tools 
  • Fast and easy connection with glue, screws or clips 
  • Made of natural materials (Vermiculite) 
  • 100% healthy - do not contain any asbestos, glass or mineral fibers 
  • Easy surface treatment 
  • Non-combustible, resistant to thermal shocks

Construction boards for:

  • Heat radiant fireplace enclosure without added heat accumulating elements 
  • Heat radiant fireplace enclosure with abuilt-in heat accumulating element 
  • Heat radiant fireplace enclosure with built-in heat accumulating element insert with heat accumulating set 

Technical data

Basic sizes [mm]

1200 x 600 x 25

Density [kg/m3]  


Classification temperature [°C]


Heat capacity [kJ/kgK]


Thermal conductivity at 800 °C [W/mK]


Tolerances of boards:
- density ± 10%
- thickness ± 1 0,3 m3

Grenatherm in accordance with ČSN EN 13501:1, reaction to fire, class A1 - non-combustible

Weight of board (kg) No of boards (pcs) Total weight of full palet (kg) No of pallets on truck (pcs) Total weight on truck (kg) Sizes of full pallet
width – length - height  (mm)
25 750 13,5 110 1 555 15 23 325 1210 1210 1575