Which of the two wall constructions is "better"?

Hello,

we are currently in the exploratory phase of our basic construction method. We currently have 2 regional providers which, however, differ significantly, especially in the exterior wall structure:

Wall structure A: Fermacell / wood fiberboard (installation level) / OSB / cellulose / wood soft fiber insulation board / plaster (total wall thickness for kfw55 37cm)
Wall structure B: Fermacell / cellulose / wood fiber insulation board / plaster (total wall thickness for kfw55 31 cm)

Both manufacturers produce their walls in a closed hall including the windows and interior fittings.
I am of the opinion that if properly built, the installation level can be omitted. Additionally, this creates living space.

For us, the question remains whether wall structure B has any further disadvantages compared to wall A.
In house A, the OSB board acts as a vapor barrier. In house B, the classic vapor barrier is missing.
Does this result in an advantage or a disadvantage for me (or maybe both)? Does anyone reading this possibly live in a house with wall structure B?

I hope you can help me shed some light on my lack of knowledge :)

In this sense, thank you and Merry Christmas

donny

Hello

I have already worked with both wall constructions. I would always choose a wall construction with an installation level. The many potential sources of error are then limited to a few. Subsequent work is also easier to carry out. Furthermore, in timber construction, I would always separate weather protection and thermal insulation/exterior wall.

Olli

We currently have 2 regional providers who differ significantly, especially in the exterior wall construction:

Are you sure that these are the most significant differences and not just the ones that stand out to you the most? It is often not the parameters considered suitable "at the beginning of the journey" that ultimately drive the decision forward. Are the two providers otherwise "too" comparable (both large brands or both small carpentries, ...)?

Are you sure that these are the most significant deviations and not just the ones that catch your attention the most?

Since I am not an expert, that can't be ruled out :). My idea was exactly to work from the outside inwards. In other words, to start with the exterior wall. Do you think I am starting in the wrong place here? What would you pay special attention to?

Furthermore, in timber construction, I would always separate weather protection and thermal insulation/exterior wall.
Olli

What do you mean by that? Does one of the two walls lack weather protection?

Thanks to both of you

Hi

But a weather protection is present on both. The plaster. I would only change the wall structure in this respect, e.g. from inside to outside stud frame with insulation, wood fiber insulation board, air layer, plaster carrier board, plaster

Olli

My idea was to work from the outside in at first. That means starting with the exterior wall. Do you think I'm starting off on the wrong foot here? What would you particularly pay attention to?

So I guessed right: you simply picked a thread from the knot of facts to pull on first :-)
"Wrong" well - it is an understandable intuitive approach, and you are in good company with it. But not so effective in terms of results.

I would "pay particular attention" initially not to anything parametric, but I recommend you to start by creating your wishlist. For example, with a qualified room list. That could start with "living room" and be qualified with "approx. 30 sqm, includes dining, but cooking separate, possibly fireplace."

Personally - but this is no universal recipe - I would always begin my own home planning with my current apartment - i.e., with the question why I would not simply replicate it 1:1; and then describe the places that would have to be different. Then rooms might have to be added (for children that are still planned, or for desired separable functions - e.g., closet out of the bedroom). Then comes the fundamental question: split the room list or bungalow, for example.

What is already settled: plot found, house exhibitions visited, ...?

I would only change the wall structure to the extent

However, one would need to know what kind of providers these are: for requests to change wall structure, small carpenters will go along, but with large brands it will mean choosing a different one.