Our attempts with building experts to "detect" further defects were not successful; we encountered disappointing professional knowledge.
We will definitely need further expertise, that is clear, but we will first complete the ongoing process to see where we stand.
We are increasingly realizing that our own site manager, to put it mildly, was not always close to the truth, and now it is also about the question of possible negligence and, if so, in which category it should be classified.
Here, I primarily see you needing your lawyer’s expertise so that the court cannot be told similar tall tales by the experts as you were by the experts questioned so far. What exactly is an "own site manager"? – apparently, an expert was not called along the way but "posthumously."
Back to the topic of purlins, which by the way are middle purlins.
And what are the base purlins made of here?
You have already been very helpful to others in this forum, but if I may ask, where do you get your assessment regarding the square purlins?
Calling the purlins "square" because of their overall cross-section is misleading for BSH (glulam timber).
Okay, I am a layman, far from being able to really judge this. One theory was that wood gluelines rarely tear at the glue itself, but rather in the wood area. This would mean the glue joint is "stronger" than the wood itself.
At first, the horizontal "leaf spring" you mentioned makes perfect sense to me. But isn’t it so that due to the gluing, which is stronger, a “new horizontal” layer is created, naturally "interrupted" by the (stronger) glue lines?
I have been a professional for four decades and base my assessment not only on professional practice but also on having attended school long before PISA (where compulsory schooling was not only a right to stay until midday but at the same time a real learning opportunity). That is why I can correctly spell "Füsickunterricht." The image that has been successfully planted in your mind of the glue layers as a sort of metal-strong board layer in what I call a laminated package of the board stack is cute and no truer than your "site manager." The only thing true about it is that a crack more often runs between fibers than along the glue joint at the edges of the boards. My "follow-up question"
Either the applications / load cases are different, i.e., two purlins with the same orientation are functionally identical (namely the pair of base purlins), and the third is the ridge purlin, then it can make sense.
you have not answered so far.
But I only spoke up here at all so that you would not die foolish (made so). I need my time for my work as a consultant (preventatively, so that those I advise do not become victims of charlatans and swindlers and build butcher shops), therefore I decided against a career as an expert witness. I do not want negative energy from other people’s misfortune to spoil my joy in my profession.