ᐅ How are windows properly installed nowadays?

Created on: 3 Jul 2020 09:12
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Seven1984
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Seven1984
3 Jul 2020 09:12
Hello everyone,

I am currently building a KFW55 house, and a window installer told me that until a few years ago, the reveals had to be smoothed out completely, a sealing tape was installed, and so on. However, nowadays the foam has been improved, and windows are being foam-insulated again.

Is that correct?
Thanks, regards
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Tego12
3 Jul 2020 10:27
And above all, no to the same thread being posted in multiple subforums.

Edit: I see you have already deleted the content in the other one. Sorry.
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Seven1984
3 Jul 2020 10:32
Yes, exactly, it was the wrong forum, but I couldn’t delete the post itself.

What is the correct procedure according to the current state of the art?
Thank you very much!
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dab_dab
3 Jul 2020 10:35
In my opinion: smooth plaster finish in the reveal, then RAL installation – basically as your window installer supposedly did until a few years ago.
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guckuck2
3 Jul 2020 12:08
RAL installation does not exclude the use of foam at all. Likewise, a compression tape is not the ultimate solution.
As long as the products used are properly certified and correctly installed, it is absolutely fine to use foam as well.
I would even argue that using only compression tape as the middle sealing layer is unnecessarily economical. Filling cavities with foam additionally does no harm and increases the insulation value at that spot.

Neither foam nor compression tape are intended to compensate for poorly measured windows. However, both materials can be misused for poor workmanship. You effectively avoid this by informing the impatient site manager that the windows will not be ordered according to the plan but only after on-site measurement by the window manufacturer (warranty chain!). The construction may then take longer, but you will get properly fitting windows, and no one will be motivated to try to force the windows to fit in any way...
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Jann St
16 Jul 2020 14:51
Hello,

There are two proper ways to install windows correctly (this refers to installation behind the insulation layer, not within the insulation layer).

1) Using a "3-D compression tape" on three sides—right, left, and top—these are usually called Trioplex or something similar. There are tested types for driving rain, airtightness, and soundproofing (hence Trio). A standard compression tape does not have all the necessary approvals. Wedge the window at the bottom to level it and then foam it in place. Afterwards, cut away the insulation on the outside and apply a driving rain-tight tape (e.g., Würth or similar). This also applies to windows with a windowsill, which can become leaky. Attach an airtightness tape on the inside at the base point.

2) Use three-sided compression tape or foam for sound insulation, and apply driving rain-tight tape on the outside and airtight tape on the inside.

I prefer option 1. Airtightness is definitely better because installation errors are less likely (such as wrinkles not being sealed, etc.).

When using compression tapes, the joints of calcium silicate blocks do not necessarily have to be smoothed out, as the tape adapts very well to all unevenness. However, I still think it should be done. Likewise, any offsets in the masonry should be leveled—even though, in my opinion, a skilled craftsman should create a window reveal without offsets.

I can gladly demonstrate the method with the 3-D tape.

The topic of balconies or terraces involves somewhat different sealing methods for floor-to-ceiling windows on the exterior side.

Best regards,
Jann