Calcium Silicate Boards – All Material Information & Prices

Calcium Silicate Boards – All Material Information & Prices

Calcium silicate boards are used when it comes to interior renovation. They require a high level of manual skills and are much more expensive than polystyrene panels as insulating material. However, their installation can be carried out very quickly. In addition, calcium silicate is a completely harmless insulating material in terms of building biology, which makes it far superior to polystyrene panels. The main application for calcium silicate boards is mold control.

Good insulation, excellent breathing

Calcium silicate panels are mineral insulating materials made from silicon dioxide, calcium oxide, water glass and cellulose. Like sand-lime bricks or aerated concrete, they are hardened with hot steam. At 0.053-0.07 W/mK, calcium silicate panels have a sufficiently good insulating value to be recognized as an insulating material by the EnEV.

However, the greatest strength of calcium silicate boards lies in their capillarity. These panels absorb room and spot humidity extraordinarily well and release it again in a controlled manner. The result is always sufficiently dry walls that no mold can form on them. This is what makes the calcium silicate boards so interesting for the renovation of old buildings with listed facades.

Rescue for historic buildings

Due to their breathability, calcium silicate panels are particularly suitable for interior insulation . This makes them interesting for the renovation of buildings that have a facade that is worth protecting. The measures triggered by the EnEV have a high energy saving effect. However, the thermal insulation composite system usually attached to the outer wall usually consists of plastered polystyrene panels. As a result, more and more houses look exactly the same from the outside, which has already led to massive criticism. So that the cities and streets don’t lose their face completely, more and more interior insulation is now being used. This does not even apply exclusively to houses that are listed buildings. Calcium silicate boards are ideal for this for several reasons:

Advantages and disadvantages

… of calcium silicate panels

+ Simple processing (which, however, requires knowledge and care)
+ Boards can be drilled through without heat loss
+ High PH value, also contributes to resistance to mold
+ Rooms are heated directly, there is no need to warm up the outer walls (warm wall effect)
+ As a result, the interior rooms heat up more quickly
+ Non-critical in terms of building biology
+ Excellent fire protection
– Danger of “barrack climate”
– Thermal conductivity is not optimal
– No load-bearing capacity
– Expensive
– Challenging in terms of the coating
– Loss of room area due to thick insulation boards

Calcium silicate boards can easily be cut to size with a hand saw. Full-surface gluing with a notched trowel is recommended for assembly. With a full-surface gluing, an accumulation of moisture behind the panel is effectively avoided. Calcium silicate is one of the alkaline minerals. In contrast to clay plaster, this makes it particularly resistant to mold growth. With external insulation, a heating system must first heat up the external wall before an even feel-good climate is created in the room. This does not apply to internal insulation with calcium silicate panels. The interior also heats up much faster than with exterior insulation. This makes interior insulation made of calcium silicate panels particularly suitable for rooms that are only used for a short time. Good landfillability is an enormous advantage of calcium silicate. Massive problems and cost increases for owners of houses insulated with polystyrene are to be expected here. With calcium silicate insulation, homeowners can therefore be relaxed when it comes to disposal costs.

Calcium silicate panels are also clearly superior to polystyrene panels when it comes to fire protection. As mineral insulating materials, they are completely non-combustible. The topic of fire hazard is becoming increasingly virulent with polystyrene panels. Calcium silicate panels are not only non-flammable, but they also reliably shield sources of fire from the outside. Forest or road fires, therefore, have a much harder time spreading to the house with calcium silicate panels.

The “barrack climate”describes a phenomenon in which the air inside buildings “stands still” due to massive insulation. This occurs above all when there are large temperature differences from the inside to the outside. The reason for this is the lack of heat buffers, in which a certain exchange of air takes place. The slab itself is unsustainable. Dowels for hanging cabinets and pictures, therefore, have to be particularly long, since the calcium silicate board has to be completely drilled through. Compared to other insulating materials, which are also significantly cheaper, calcium silicate has to accept compromises in the insulating effect. The price is still the biggest snag when installing calcium silicate panels across the board. However, if you add the disposal costs, the additional price for calcium silicate compared to polystyrene plates is somewhat offset.

The whole breathable effect of calcium silicate boards can be negated if a diffusion-tight paint (eg latex paint) is used. Calculated for the whole house, several m² of living space are lost due to the use of thick insulation boards made of calcium silicate.

Processing calcium silicate boards

The following tools are required to process these insulation boards:

  • Hacksaw (approx. 12 euros)
  • Fuchsschwanz (Ca 15 Euro)
  • Drill with stirring rod and drill bit (approx. 120 euros or 15 euros for rental)
  • Mortar trough (approx. 12 euros)
  • scale (approx. 5 euros)
  • Glättspan (Ca 8 Euro)
  • Notched spatula (approx. 18 euros)
  • Tassel (approx. 5 euros)
  • Painting set (paint roller, brush, extension stick) (approx. 12 euros)
  • Rubber hammer (approx. 15 Euro)

Handling glue and plaster is a very messy business. Wearing suitable clothing is therefore urgently required.

The calcium silicate board is also called “climate board”. It ensures a balanced room humidity in the room. If it is used to combat mold, existing mold must first be completely removed. Remove wallpaper and loose paint before coating. Spraying the shell wall with a mold killer before gluing it with calcium silicate panels creates additional security. An additional primer improves the adhesion of the adhesive.

The plates must be prepared with millimeter precision. Socket holes can be made with a core drill attachment and a normal drill. The work here is also very precise. The panels are coated with a special primer using a brush. The calcium adhesive is then mixed and generously applied with a smoothing chip. After application, the layer of adhesive is given a defined structure and thickness with a notched trowel. Only now is the panel firmly pressed against the wall with the primed side. It must be glued to the wall over its entire surface. The plate easily withstands light hits with a rubber mallet. Corners, edges and especially gaps should definitely be avoided. Slight overhangs can be smoothed out with a float.


The price for calcium silicate panels depends on their dimensions and the quantity purchased. A standard dimension for these insulation panels is 1.00 m wide and 1.22 m long. Due to the low density, these large panels can also be easily processed by a single worker.

Recommended prices per m²

2.5 cm thick = EUR 25.50
3 cm thick = EUR 30.50
4 cm thick = EUR 36.90
5 cm thick = EUR 42.50
6 cm thick = EUR 46.90
7 cm thick = EUR 48.00
8 cm thick = EUR 50.00

For a normal room wall without windows, you have to calculate with 70-125 euros for the insulation boards per meter length (room height 2.75 m). The thicker the insulation board is chosen, the better it protects against the outside temperature. But a lot does not necessarily help a lot, especially in thermal insulation. Above a certain value, the increase in the insulating effect is only minimal with each additional structure. The size of this value depends on the existing building structure. A precise calculation provides information about which heat protection is desired and makes sense. This is best done with the help of an energy consultant.

There are extra thin and narrower calcium silicate panels for window reveals. These leave enough space for a pre-assembled radiator to ensure ideal air circulation. The panels, which are almost 2 cm thick, measure 0.5 mx 0.24 m and cost just under 7 euros each.

The adhesive for calcium silicate boards costs about 1.50 – 1.70 euros per kg. You can count on approx. 3-4 kg/m². The amount depends on the thickness of the panel and the unevenness of the subfloor. Primer costs about 5 euros per liter. However, the primer is very productive. One liter is sufficient for approx. 3-10 m², depending on the absorbency of the substrate. It is a matter of taste for the user whether the climate panel is plastered over or smoothed out to a mirror-smooth finish.

Breathable and excellently workable lime filler for climate boards costs approx. 1.60 per kg. Approx. 3 kg filler is required per m² for a 2 mm thick layer. Air conditioning plaster is apparently cheaper at 1.30 euros per kg. However, a thickness of 10 millimeters is required for correct plastering, which corresponds to approx. 10 kg of ready-mixed mortar per m². This solution is therefore significantly more expensive than lime putty. A reinforcement fabric for approx. 2.50 euros per m² effectively prevents cracking when plastering or filling.

Finally, paint has to be on the wall. It is strongly discouraged to wallpaper a wall made of calcium silicate boards. Latex paints are also unsuitable for climate panels. A liter of paint for calcium silicate panels costs around 5.60 euros. It is sufficient for approx. 6.5 m².

In summary, the following costs result for one m² of wall covered with a climate panel:

  • Climate plate: 25.50-50 euros
  • Primer: 0.5 euros
  • Glue: 5 euros
  • Spatula: 5 euros
  • (plaster: 12 euros)
  • Reinforcement fabric: 2.50 euros
  • Color: 1 euro
  • Together: 43.50 – 76 euros, depending on the thickness of the climate panel and the type of cladding

But you have to consider: The maximum thickness of 8 cm is really necessary and sensible in the rarest of cases. Climate panels with a thickness of 3-8 cm are used for normal applications. In any case, the use of climate panels has done the maximum possible to prevent mold infestation. However, this only applies to mould, which is caused by a poor indoor climate and thermal bridges. Even the best climate panel is powerless in the case of massively damp walls due to a damaged exterior plaster or a damaged water pipe.

Calcium silicate panels are ideal for renovating basements. With the help of these panels, a fully usable space can be created from a previously damp, musty vaulted cellar. The increase in living value and thus also the increase in value of the house should be taken into account given the initially high costs of this renovation measure. However, the prerequisite for this is absolutely dry external walls.

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Tips for speed readers

  • Calculate panel thickness with Energy Advisor
  • Always prime boards
  • Always coat boards so that they are open to diffusion
  • Plaster fabric prevents cracks
  • Refurbished basements increase the value of the house