Window installation - faulty sealing tape or wait?

Hello everyone,

our general contractor actually got a Monday appointment for our windows last week. The German-speaking window installer explained to me that they install a sealing tape / swelling tape on the outside. Due to the 2-3 °C, it expands rather slowly. They started on Wednesday and by Thursday night it should have expanded. They also used a hot air blower because, according to him, they want to avoid the window installation foam applied afterwards from getting under the swelling tape. That’s why the swelling tape should be fully expanded (up to the masonry) before they can foam from the inside.

Last night I was able to take photos of two different windows (doors) on the ground floor from the outside o_O
According to the photos, it seems to me that they have also cut the swelling tape too short at their height (i.e., the part that should have expanded). You can see the curves on the surface, which should actually press against the window reveal, right? Doesn’t the window installer use a "uniform" swelling tape of the same height for this?

The swelling tape is the gray one (front, since the photo is from the outside) and behind it is the slightly differently colored violet-gray installation foam.

Should I wait until next week, when a clear temperature increase of 8-9 °C is expected, for the swelling tape to fully close and touch the window reveal everywhere? Or should I say before acceptance that I want the swelling tape fully closed everywhere? For that, they would probably have to completely reinstall the affected windows, right? Not all windows are like this. Most of the windows have swelling tapes that fully contact the reveal from the outside. I can no longer see anything inside because after the installation foam a black adhesive tape (with a cotton surface?) was applied to the joints.
What do the experts here think? I don’t want to invite unnecessary thermal bridges through such errors. Especially our window expert can certainly tell me what is going on there.

In the 3rd picture, they apparently simply cut the swelling tape too short in length, so there is about a 1 cm high swelling tape gap. It has expanded well there and presses against the window reveal. Should I just foam that small gap closed? But the waves and curves in the swelling tape surface, which unfortunately are partly significantly away from the window reveal, are outside the tolerance range, right?

Many thanks for your answers.

Have a nice weekend and in advance a Merry Christmas season.
Ann

To me it looks like the tape cannot fully expand because of the foam. Hence the differences in height. The tape comes in different heights, for different gap widths, so it is of course possible that the installers chose the wrong tape, although to me, as stated in the first sentence, it looks like the foam is in the way. The tape belongs, as far as I know, to the sealing level and must be used all around. Therefore, there should be no gap between the sections. This was explained to me by my window installer when he tore off a piece of the tape that was too short and replaced it with a continuous piece. The swelling can take a few days at these temperatures until it fully closes, almost a week in our case.

We recently had a similar discussion here, with somewhat different positions on the "Glattstrich" aspect:

It looks to me as if the tape cannot fully expand because of the foam. Hence the differences in height. The tape comes in different heights, i.e. for different joint widths; it may of course be that the installers chose the wrong tape, although to me, as written in sentence one, it looks like the foam is in the way. The tape belongs, as far as I know, to the sealing layer and must be used continuously all around. Therefore, there should be no gap between the sections. This was explained to me by my window installer when he tore off a piece of tape that was too short and replaced it with a continuous one. The swelling can take several days at these temperatures until it fully seals over the entire surface, in our case almost a week.

Yes, in the photo it really looks that way, but the tape is in front of the foam and the foam is definitely not in the way at these spots. That’s why I am also puzzled by the waves on the surface of the compressible tape. And the small piece where they were too short, how are they supposed to fix that now? Take the window out completely again and use compressible tape that is long enough? Or would it suffice to fill that small piece with mounting foam? Since the principle "inside tighter than outside" is applied when installing windows, one could say that these small spots are not so bad? Or is this actually shoddy work? thanks also for your thread reference. Unfortunately, it could not really answer my above question. There was a clean finish at my window reveals. However, at 2-3 windows the compressible tape does not adhere to the reveal at every spot. Either it will come later and it really takes a few days, or it will just stay that way. Fill with foam? Or will another tape be applied on the outside as well, like the one currently visible on the inside: Thank you very much for your opinions and greetings from the now again very icy Swabian region.

Hi,

To me, it looks a bit like the installers were not quite sure what the purpose of the tape is.

1. The tape used is of good quality (brand)
2. The tape comes in different thicknesses but it also fills the cavity even at too low a thickness because it expands up to 8cm. However, it is no longer tight enough then, which you notice by pressing it. If it feels very soft, it was the wrong tape.
3. Foam has no place in installation with sealing tapes. I have already written something about this. The tape ensures the airtightness, driving rain resistance, and thermal tightness all in one. The gaps at the joints (often also in the corners if they cut it too short) are sealed with a cartridge sealant (a sticky substance like from a silicone gun). For example, with fall-protection windows, if you also screw tabs to the masonry, you apply another tape for airtightness on the inside in addition to the sealant (which was otherwise continuous).
4. In my opinion, the tape cannot fulfill its tasks here.

Best regards, Jann

It has actually expanded a bit more in the last few days - despite temperatures around freezing point. I will also do the pressure test sometime next week. Unfortunately, I will probably only manage to get to the construction site next weekend. Can something like this be claimed even after installation? Do I have the right to repair, and is it especially possible to do this with installed windows (i.e., replace the sealing strips afterwards)?