By insulating the building, heating costs can be reduced – this is now common knowledge. But what about consequential damage as a result of the facade insulation? Is structural damage possible? In the following, therefore, individual questions and myths will be taken up and explained.
Question: Is it true that insulation always leads to algae growth on the facade?
Sometimes you can see in buildings with external insulation that the facade changes color after years. Algae and microbial organisms colonize the facade surface.
The prerequisite for this is favorable growth conditions, such as:
- high humidity on the facade surface,
- the lowest possible drying potential of the surface due to shading of the surrounding trees and bushes,
- a high level of moisture (location near water)
- The outer wall facing the weather side or facing north with little solar radiation
Since the external surface temperatures of an insulated facade are lower (due to the lower heat transfer through the wall), facades with external insulation tend to be colonized by algae and microorganisms more frequently.
Question: Does the insulation of facades lead to an increased risk of fire?
Just like the wood in the roof structure or in the half-timbered building, the styrofoam/polystyrene is basically also combustible in a thermal insulation composite system. There are also numerous objects inside the flammable building and may also release highly toxic gases when burned. However, one should not imagine that one can simply light a thermal insulation composite system with a match.
If you want a non-combustible thermal insulation composite system, you can alternatively choose mineral wool or rock wool as an insulating material. These insulation materials are not flammable. Furthermore, a curtain wall or the additional construction of a front wall can support fire protection.
Question: Does insulation lead to moisture and mold damage?
The temperature of these external walls increases as a result of the external insulation. Since moisture always condenses at the coldest point, the exterior walls are even protected by the exterior insulation. The walls are in the warm area, and a “coldest point” can be assumed on uninsulated outer walls but no longer in insulated areas. Due to these higher wall surface temperatures, from a building physics point of view, the moisture from the (humid) room air can condense much more poorly; the wall is, therefore, drier overall. The drier the wall surface, the less likely the risk of mold growth.
Of course, this means that you must continue to ventilate.
Risk of moisture and mold damage
Moisture and mold damage could occur on insulated external walls in the event of rising dampness, water damage, or moisture penetrating from the outside due to structural damage. However, these causes of damage must always be eliminated and can lead to moisture and mold damage even on uninsulated external walls.
Question: Do woodpeckers destroy the insulation and prefer to nest in the insulation?
In the vicinity of parks and gardens, birds may occasionally build a hole in the facade insulation and nest in it. Once a bird has recognized this principle, it will try again and again. Every woodpecker is different. Therefore, some creativity is required when taking countermeasures.
Choosing another insulation material is of little help here. However, if the problem is already known before starting the insulation work, a curtain wall could be chosen as an alternative instead of a thermal insulation system. In the case of a curtain-type facade construction, a substructure made of wood or metal profiles is attached to which a facade cladding is made of a wide variety of materials (wooden formwork or panels, fiber cement panels, etc.) can be hung as protection against weather and birds. The thermal insulation is, of course, inserted between the substructure. A windproof design is always important here.
Further alternatives could be, for example:
- Choose thicker plaster, reinforce reinforcement
- choose smoother plaster
- offer alternative nesting options for the woodpecker
- test different scarecrows
- Attach metal sheets to house corners