ᐅ KfW 70 - 36 cm Ytong blocks - Ventilation system

Created on: 22 Aug 2013 18:03
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Dali
Hello everyone,

we are planning to build a single-family house with the following specifications:
- one and a half stories
- on a slab foundation
- approximately 125 sqm (1350 sq ft)
- 36cm (14 inches) Ytong blocks (without additional insulation)
- mineral-based exterior plaster
- KfW 70 energy standard
- triple-glazed windows
- heating: gas/solar; underfloor heating throughout the entire house

Regarding a ventilation system, we are unsure about which option would be the most suitable.

Our options are:
- no ventilation system (our builder believes it is not necessary)
- decentralized ventilation system
- decentralized ventilation system with heat recovery
- centralized ventilation system with heat recovery

We have already read a lot on online forums, and the more we read, the more confused and uncertain we become...

Thank you very much in advance for your support!
Mycraft31 Jan 2014 10:34
Depending on the system, the ducts need to be cleaned after 10-15 years... and all ducts before the filters every 2-3 years.

The plate valves should be maintained as needed...
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Buxel83
10 Jul 2014 08:12
Hello, I spoke with a construction company yesterday. I’m not sure if I’m allowed to mention the name, but the wall construction consists of polystyrene blocks with a concrete core.

They told me that a ventilation system is MANDATORY to meet the KfW70 standard!?!?

With another construction company using 36.5cm (14.4 inches) Ytong blocks, there was never any mention of a ventilation system!?!

So, what is correct?
B
Buxel83
10 Jul 2014 19:40
Is there anyone who can provide a statement on this???
One0010 Jul 2014 19:52
None of it is entirely true, as it always depends on the situation. Do the expanded polystyrene blocks have a concrete core?
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Buxel83
10 Jul 2014 22:53
Is there anyone who can provide a clear statement on this???
One00 schrieb:
None of it is entirely true or false, because it always depends. Do the expanded polystyrene blocks have a concrete core?

Yes, they do have a CORE.

And what does that mean now? Is there a regulation or requirement?
Putting aside the pros and cons of such a system.
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Bauexperte
11 Jul 2014 00:19
Good evening,
Buxel83 schrieb:

Hello, I spoke with a construction company yesterday. I’m not sure if I’m allowed to mention their name, but the wall structure is made of polystyrene blocks with a concrete core.
So what we call a "squeaky house" internally in the industry.
Buxel83 schrieb:

I was told that to meet the KfW70 standard, a ventilation system is MANDATORY!?!?
With another construction company using 36.5 cm (14.5 inches) Ytong blocks, there was never any mention of a ventilation system!?

So what’s correct?
There are two possibilities – either the seller is an idiot or, more likely, he simply lied to you because he couldn’t bring himself to tell the truth. There is no obligation to install a ventilation system; at least not yet. However, that doesn’t mean it’s not strongly recommended for the wall structure used by the competitor.

Regards, Bauexperte