ᐅ Facing bricks directly on aerated concrete blocks?

Created on: 19 Apr 2014 20:36
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baschti
Hello,

we are planning to build soon. Since we are constructing a KfW 70 house with 30 cm (12 inches) Ytong exterior blocks and therefore will not add any insulation to the facade, my question is whether I can lay the brick veneer directly onto the Ytong or if I need to leave a 1-2 cm (0.4-0.8 inches) gap?

My concern is that if I use brick slips, they are glued directly to the Ytong, but standard 11.5 cm (4.5 inches) brick units are usually laid with a certain gap. Unfortunately, I only find this advice when insulation is involved, which I do not want, as I have read a lot of negative things about that, like mold, moisture, etc.

So should the brick be glued directly to the Ytong or installed with a gap?

I hope someone can help me!
emer20 Apr 2014 22:12
How do you achieve KfW70 with that?
emer20 Apr 2014 22:45
I have a possibly naive question. I also received a calculation from my structural engineer based on the same DIN standard as in the document. It results in a primary energy demand of 68 kWh/(m2•a) (6.3 kWh/(ft2•year)). For compliance with the energy saving regulations for new buildings, 73.30 would be required. Your primary energy demand is stated as 79.7. To me, this would not even comply with the energy saving regulations??? I’m confused. Could someone please clarify this for me?
emer20 Apr 2014 22:50
I will try again in German *g*

My calculated primary energy demand = 68.
On the document from my structural engineer, it says I need 73.30 to comply with the energy saving regulations.

On baschti’s document, it says 79.7.

Both are based on the same DIN standard.

That is higher than the 73.30 for the energy saving regulations given by my structural engineer (so above "KFW 100"?).

How can this be explained?
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baschti
21 Apr 2014 09:21
Maybe this is related to the floor area, type of energy, etc. When I search for energy performance certificates on Google Images, the maximum values according to the energy saving regulations always appear different.
emer21 Apr 2014 09:34
Yes, but energetically speaking, there is a significant difference between 100 and 73.
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Bauexperte
22 Apr 2014 08:50
Hello,

I was actually expecting €uro to respond here; he is probably still enjoying a well-deserved Easter holiday.
baschti schrieb:

I was wrong, sorry, it’s only 24cm (9.5 inches) of roof insulation...
I would have been surprised too, but 240 mm (9.5 inches) is already very good.
baschti schrieb:

Unfortunately, I can only find info on the slab like concrete quality C25/30
That is standard at first, since the structural engineer has a say in the slab thickness—based on the soil report. But I’m not aware of any supplier who voluntarily offers a thicker slab.

Is that not the certification for your bungalow?

KfW 70: The decisive factor is the annual primary energy demand Qp. Here, the maximum value for a building may, for example, be up to 70% of the reference building’s value (100%) according to the 2014 Energy Saving Ordinance. And the transmission heat loss H’T must not exceed 85% of the reference building’s value according to the 2014 Energy Saving Ordinance. With a primary energy demand of 79.7%, you will not achieve the desired KfW 70 rating; at least not without additional measures.

Regards, Bauexperte