ᐅ Rafter roof instead of a purlin roof without prior consultation

Hello,

I have the following rather bold problem:

I purchased a semi-detached house, and for some reason, the planner/structural engineer of the two units did not take the overall context into account. So, it seems they designed a purlin roof (with two main purlins) for my house, but a rafter roof for my neighbor’s.

Throughout the entire construction planning, I always agreed to a purlin roof (even though it wasn’t very important to me; I just liked the idea of having two visible purlins in the attic). By now, the roof is finished, and only recently did I notice the absence of the purlins. I was never informed about this.

So, my question is: Apart from (aesthetic) aspects, are there any other disadvantages? How should I best negotiate with the builder regarding a refund (which seems justified if the house is not built according to my expectations)? And what amount would be realistic?

Are there any further issues, possibly structural ones?

If needed, I can attach a picture of the purlin roof design.

Thanks for your help (: