ᐅ New Construction: Sand-lime Brick + External Thermal Insulation Composite System = Mold?
Created on: 3 Jan 2014 23:39
E
erlHello,
a mortgage advisor discouraged us from buying a newly built semi-detached house because the exterior walls are made of sand-lime brick masonry and the facade is constructed as an external thermal insulation composite system (ETICS) using rigid polystyrene foam boards with synthetic resin render.
His reasoning: This results in an airtight building with zero breathability. Without a ventilation system inside the house, mold growth would be almost inevitable. According to him, this type of construction is only done to meet the 2009 energy saving regulations cheaply and is no longer considered state of the art.
Unfortunately, I have no knowledge about construction or modern energy-efficient building methods.
Is what he says accurate?
I would appreciate your opinions.
Thank you in advance.
a mortgage advisor discouraged us from buying a newly built semi-detached house because the exterior walls are made of sand-lime brick masonry and the facade is constructed as an external thermal insulation composite system (ETICS) using rigid polystyrene foam boards with synthetic resin render.
His reasoning: This results in an airtight building with zero breathability. Without a ventilation system inside the house, mold growth would be almost inevitable. According to him, this type of construction is only done to meet the 2009 energy saving regulations cheaply and is no longer considered state of the art.
Unfortunately, I have no knowledge about construction or modern energy-efficient building methods.
Is what he says accurate?
I would appreciate your opinions.
Thank you in advance.
N
nordanney4 Jan 2014 20:50erl schrieb:
What alternatives are there for masonry to comply with the 2009 Energy Saving Ordinance so that a "controlled ventilation system" is not required?There are various options for masonry (e.g., monolithic construction, facing brick), but the issue of an airtight building remains!!!
As mentioned before: A mechanical ventilation system is not absolutely necessary, but aside from that, the energy saving regulations set very clear requirements regarding the airtightness of the building envelope. Therefore, all houses that meet these standards (which includes all homes built nowadays) are affected equally—regardless of whether they are constructed with sand-lime brick, aerated concrete, hollow bricks, timber frame construction, or other methods.
Otherwise, you probably have to build in the USA or elsewhere.
Good luck
K1300S
Otherwise, you probably have to build in the USA or elsewhere.
Good luck
K1300S
Hello,
Best regards
erl schrieb:What professional training or qualifications, especially in the field of building physics, does this "advisor" have?
....a construction financier told us about the purchase.... Is what he is saying correct?..
Best regards
B
Bauexperte6 Jan 2014 10:59Hello,
User "K1300S" described it very well; walls don’t really breathe, but where ETICS is applied, there is absolutely no diffusion. From my subjective point of view, ventilation is mandatory here—whether central or decentralized—because, firstly, homeowners often lack the expertise to calculate it correctly (sometimes it actually works without ventilation), and secondly, they do not stick to the necessary ventilation intervals during the first years after moving in.
Furthermore, the construction financier’s further explanation is not correct. Many builders, especially more traditional ones, rely on calcium silicate bricks because they don’t have to worry at all about sound insulation, and homeowners cannot really complain about this later. Since calcium silicate bricks provide very poor thermal insulation, a thicker ETICS must be applied. Therefore, calcium silicate bricks are suitable in areas such as near railways or airports when combined with soundproof windows.
Similar considerations apply to hollow bricks, aerated concrete, or pumice blocks, which are installed with a wall thickness of 17.5cm (7 inches). Here too, ETICS must be applied for the required thermal insulation.
In my experience over recent years, ETICS is mainly used—apart from the cases mentioned above—because settlement cracks in the house disappear behind the facade. Homeowners tend to accept these cracks inside the house rather than argue with neighbors about the exterior appearance. Conversely, only a few salespeople are well trained enough to inform potential homeowners about the advantages of monolithic construction.
Best regards, Bauexperte
erl schrieb:Well, then the construction financier probably does not have much to do, since thermal insulation composite systems (ETICS) are still mostly installed.
His reasoning: This is an airtight sealed house with zero breathing. Without a ventilation system, mold would be inevitable here. This would only be implemented to meet the 2009 Energy Saving Ordinance requirements cheaply and is no longer up to date.
User "K1300S" described it very well; walls don’t really breathe, but where ETICS is applied, there is absolutely no diffusion. From my subjective point of view, ventilation is mandatory here—whether central or decentralized—because, firstly, homeowners often lack the expertise to calculate it correctly (sometimes it actually works without ventilation), and secondly, they do not stick to the necessary ventilation intervals during the first years after moving in.
Furthermore, the construction financier’s further explanation is not correct. Many builders, especially more traditional ones, rely on calcium silicate bricks because they don’t have to worry at all about sound insulation, and homeowners cannot really complain about this later. Since calcium silicate bricks provide very poor thermal insulation, a thicker ETICS must be applied. Therefore, calcium silicate bricks are suitable in areas such as near railways or airports when combined with soundproof windows.
Similar considerations apply to hollow bricks, aerated concrete, or pumice blocks, which are installed with a wall thickness of 17.5cm (7 inches). Here too, ETICS must be applied for the required thermal insulation.
In my experience over recent years, ETICS is mainly used—apart from the cases mentioned above—because settlement cracks in the house disappear behind the facade. Homeowners tend to accept these cracks inside the house rather than argue with neighbors about the exterior appearance. Conversely, only a few salespeople are well trained enough to inform potential homeowners about the advantages of monolithic construction.
Best regards, Bauexperte
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