Is an octametric measurement system mandatory?

Hello everyone,

we are currently planning our single-family house. I have learned that there is the octametric measurement system for the opening dimensions. With regard to the architecture of the house, however, we want to plan some openings individually (e.g., 1.59 instead of 1.51). According to the builder, this is no problem because the facing bricks can be cut individually.

I just keep wondering how that might look. The lintel above the windows should be built vertically (Grenadier lintel?!), and the exterior window sills should also be angled/vertical. I am not a professional, so please excuse my amateur language.

Now the actual question: Can one deviate from the octametric measurement system without any concerns, or is that not advisable?

Best regards

Depends on how often and at what points. Deviations from the stone grid lead to so-called botch pockets. These are not very conducive to the uniformity of the thermal envelope (possibly negligible with ETICS). If the masons have to cut a lot, they get into a bad mood. Whether that's bad I can't prove, but it's certainly not good. If the quality of your architecture depends on a few centimeters, your plan is not good. Tolerances in the shell construction should not be sought in the millimeter range...

Our general contractor followed the Oktameter system exactly, the 12.5cm was always the next grid step, solid house monolithic. He said, planning to the millimeter when furnishing only leads to tears (then it’s off to the new furniture with the jigsaw).

So it's about 8cm here. According to the construction contractor, no problem at all, since these construction dimensions are no longer really important nowadays. I can't say much about it, but from his point of view, it's no problem.

You contradict yourself in one thing: One should probably adhere to the standard measurement, but tolerate tolerances of a few centimeters. Well, then it doesn't matter about the 8cm... or?

I didn't understand the comparison with the furniture. It's only about 3 of 13 windows that have been made 8cm larger instead of 12.5cm.

Best regards

we are currently planning our single-family house. I have learned that there is the octametric measurement system for opening dimensions.

Oh, when then? - here: it certainly does not look like that yet, the wall sections (1.66, 2.08) also break the grid, likewise nothing like that can be seen in the exterior wall thickness (would the inner shell or the outer shell or even none of both be in the grid there?).

With regard to the architecture of the house, however, we want to plan some openings individually (e.g. 1.59 instead of 1.51). According to the builder, no problem since the facing bricks can be cut individually.

What kind of "architecture" should argue against going cleanly from 1.59 to 1.635 instead? Especially with facing bricks, I would be particular on the one hand (or not), in any case I wouldn’t want to cut them there. On the other hand: are we even talking about standard size facing bricks here, or possibly even the Kaltenthaler monastery format?
Also, the question is difficult to answer without knowledge of the reveal details.
The answer from - basically deserving a merit badge, maybe even a little saint’s picture - apparently refers to the structural wall shell but would have to be differentiated for the facing shell. With the facing shell, you can also compensate a lot with a wild bond (but that does not mean anarchy there either!).

The lintel above the windows is to be built vertically (Grenadier lintel?!), the exterior window sills also angled/vertical.

By the window sills you probably mean a "roll layer". The lintel is also wide beyond the window opening in the facing layer, so the rhythm for the lintel counts more here than for the window opening itself. For example, if you use Reichsformat facing bricks, 1.585 would be the next suitable dimension for the window sill (1.51 would also fit).

In one thing you contradict yourself: One should probably stick to the standard dimension, but tolerate tolerances of some centimeters. Well, then the 8 cm do not matter after all… or?

No. Tolerances already arise during execution; all the more they have no place in planning.

I did not understand the comparison with the furniture.

In times of CAD, planning to the millimeter by builders exists. House and furniture, and then long faces when finished dimensions are never that exact, and the centimeters were hit by skill. I myself adjusted brand new furniture with a jigsaw in the first house. Strangely, my wife does not forget that.