ᐅ Is it normal to have polyurethane foam between the sealing tape and the window?

So, now I have to chime in as well. I’m new here and came across your post by chance. I’m a master carpenter and managing director of my own company, and I regularly install uPVC windows. It’s important to know that there are several ways to install a window according to RAL standards or current industry best practices. The photos you showed are simply a disaster. What was written about them is also not entirely correct.

First of all, the RAL installation method requires that the connection joint be tighter on the inside than on the outside. The exterior side of the window must be resistant to driving rain. In the installation you showed, a triple-layer tape from Illbruck or a comparable manufacturer was used. This tape combines all three layers in one: (driving rain resistant -> insulation -> vapor tight). The joint must not exceed the manufacturer’s specifications anywhere, otherwise airtightness cannot be guaranteed (1st defect). Additionally, foam was used for the reveal because the windows were clearly measured too small (2nd defect). However, foam does NOT provide vapor tightness. This means the window would not be sealed at all, even if the tape were properly applied everywhere (3rd defect).

Furthermore, the tape was wrapped around the corners of the window frame. This should not be done because the tape cannot unfold correctly at these points. Instead, the tape must be cut and then overlapped with a slight extension on the other side to ensure a proper seal (4th defect).

Based on the photos, I can say that the windows will need to be completely removed and reinstalled fresh (and correctly). In my opinion, you don’t need an expert report for now, as these defects are MORE THAN OBVIOUS. Don’t let this get you down.

Since I am currently under a lot of work pressure and also handling the electrical planning on the side, I had pushed the window issue out of my mind.
The window installer is supposed to receive the window contacts next week, which will be additionally installed for the tilt position (replacement is not possible since they are in the wrong place). Then he also wants to finish the rest.
I had a friend who has been a construction manager for several years look at it, and he tried to downplay the issue a bit. He said that with my 1960s hollow blocks (24cm (9.5 inches)) it wouldn’t make much difference if the installation wasn’t perfect. It would be different if there was additional exterior insulation. He only used a lighter to check if any air was coming through and pointed out a few spots that are absolutely unacceptable. Unfortunately, he also communicated this to the window installer. The plan is now to just scrape out those spots and fill them fully with foam. However, everyone familiar with windows says that the installation is completely unacceptable. In my opinion, this is obvious even to a layperson; otherwise, I wouldn’t have had doubts from the very beginning.

Let’s assume it is left as is and I simply don’t pay for the installation (I doubt it would be done properly even if this company reinstalled it). What problems could I expect? Please also take the old masonry into account.

What are your reasons for wanting to keep the windows in place?
Is it just because you’re busy with work?

It probably wasn’t cheap, right? So report the defects and have the responsible contractor provide the service you paid for... period...

Since these are obvious issues, make sure to send written notices by registered mail and demand replacement and proper installation... if necessary, involve a lawyer...

What could happen? Rot, mold, etc....

As I said, I am concerned that this company will not reinstall the windows correctly or might even cause more damage. For example, not properly removing the old foam, damaging the windows, or making another mistake.

Since rot or mold is a real problem and not just a possible issue of low insulation value, I have now asked them to fix it. They want to correct all 9 windows plus the patio door in one day...

Careful removal seems more critical to me than reinstalling.

To prevent them from making mistakes again, I want to tell them exactly how to do it. I assume the best solution would be to plaster the reveals thicker and then use the sealing tape. However, this will certainly not be possible within that timeframe. Therefore, my question: in most places, there is about 3cm (1 inch) of clearance.

What would you suggest?

1.) Instead of using the Würth Vkp Trio 66/5-10 tape for the actual gap, use the Würth Vkp Trio 66/13-30 and just install it as is
(This would definitely be the worst solution)

2.) Insist on plastering for sure?
3.) Joint sealing tape: open to the outside and airtight to the inside, plus foam.

However, I do not have external thermal insulation composite system (ETICS / EIFS), and my window opening does not have the same width or height continuously. So, up to about half the depth, it is like in the pictures shown, then it narrows. The outer frame is still partly covered. What needs to be considered here?

I also have another question. He said that the lower window sill profile is only intended for aluminum window sills (I told him from the start that I want granite window sills). He wants to apply a 2cm (1 inch) silicone layer to level it out. I’m no professional, but that sounds like amateur work again.

What should he do correctly there? Change the profiles?

I would really appreciate it if you could help me with this.

Which region are you from? There might be a different window manufacturer available. Unfortunately, I’m not a professional either, but I would quickly get an expert or something similar involved BEFORE any repair or correction work begins.

Just the fact that they installed aluminum window sills instead of the requested granite ones ... well, it sounds as bad as: task failed – fail grade 6.

So ... get some help ... ask another window manufacturer, etc.

I am from the Darmstadt area. During my search for window manufacturers at that time, there were also some local ones. After the poor workmanship, I called a few to take a look and possibly fix the problem. I even offered payment for the inspection. Unfortunately, no one was willing to do it. On the one hand, no one wants to assess the work of others, nor do they want to work on windows installed by someone else.

How can I get in touch with an expert? Who should I contact for this?