ᐅ Is an octametric measurement system absolutely necessary?

Hello everyone,

We are currently planning our single-family home. I have learned that there is the octametric measurement system for opening sizes. However, considering the architecture of the house, we want to design some openings individually (for example, 1.59 meters (5.22 feet) instead of 1.51 meters (4.95 feet)). According to the builder, this is not a problem since the facing bricks can be cut to fit.

I keep wondering how this will actually look. The lintel above the windows is supposed to be built vertically (a vertical lintel?), and the exterior window sills will also be angled or vertical. I am not a professional, so please excuse my basic terminology.

Now the actual question: Is it generally safe to deviate from the octametric measurement system, or is that not advisable?

Good luck!

It depends on how often and at which points this occurs.
Deviations from the brick layout lead to so-called patching pockets. These are not very beneficial for the uniformity of the thermal envelope (possibly negligible with external insulation systems).
If the masons have to do a lot of cutting, they tend to get frustrated. I can't prove that this is bad, but it certainly isn’t good. If the quality of your architecture depends on a few centimeters (inches), your plan is not well designed.
Tolerances in the shell construction phase should not be expected to be within the millimeter range.

Our general contractor followed the Oktameter system exactly; the 12.5cm (5 inches) increments were always the next grid step, solid monolithic house. He said that planning in millimeters for the furniture only leads to frustration (then you have to adjust the new furniture with a jigsaw).

So, it’s about 8cm (3 inches). According to the builder, this is no problem at all, since these construction dimensions are no longer really important nowadays. I can’t say much about it, but from his perspective, it’s definitely not an issue.

In one point, you contradict yourself: the standard dimensions should probably be followed, but tolerances of a few centimeters are acceptable. Well, then 8cm (3 inches) wouldn’t really matter... right?

I didn’t understand the comparison with the furniture. This is only about 3 out of 13 windows, which were made 8cm (3 inches) larger instead of 12.5cm (5 inches).

Good luck

lars909 schrieb:

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

Oh, when exactly? – here: https://www.hausbau-forum.de/attachments/neubau-efh-platzierung-lichtschalter-542996-1-jpeg.67543 it certainly doesn’t look like that yet, and the wall sections (1.66, 2.08) also break the grid pattern. The same applies to the exterior wall thickness, where no such pattern is recognizable (would the inner leaf, the outer leaf, or neither be aligned to the grid there?).

lars909 schrieb:

Looking at the house architecture, however, we want to individually design some openings (e.g., 1.59 instead of 1.51). According to the builder, this is no problem because the facing bricks can be cut individually.

What “architecture” would argue against adjusting neatly from 1.59 to 1.635? Especially with facing bricks, I would be quite strict (or maybe not), but in any case, I wouldn’t want to cut them. On the other hand: are we even talking about standard format facing bricks here, or perhaps the Kaltenthaler monastery format? Also, this question is hard to answer without knowing the reveal details. The answer from @Tolentino – worthy of a merit badge, maybe even a saint’s picture – obviously refers to the structural wall leaf but should be seen differently for the facing layer. For the facing layer, you can also compensate a lot with an irregular bond pattern (although that doesn’t mean total disorder!).

lars909 schrieb:

The lintel above the windows should be built vertically (Grenadier lintel?!), and the exterior window sills should also be sloped/vertical.

Regarding the window sills, you probably mean a “roll layer.” The lintel also extends beyond the window opening in the facing layer, so here the module for the lintel matters more than the window opening itself. For example, if you use facing bricks in the Reich format, 1.585 is the closest fitting dimension for the window sill (but 1.51 fits just as well).

lars909 schrieb:

On one point you contradict yourself: You should follow the standard dimension, but tolerate deviations of several centimeters. Well, then 8cm (3 inches) shouldn’t matter… right?

No. Deviations already occur during construction, which is why they have no place in the planning phase.

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lars909 schrieb:

I didn’t understand the comparison with the furniture.

Nowadays, with CAD and millimeter (0.04 inch) precision planning by homeowners, there is a big difference. People plan their house and furniture down to the millimeter (0.04 inch), then get disappointed when the actual final measurements are never that exact, and hitting the centimeter (0.4 inch) mark is already considered good. When I built my first house, I adjusted brand new furniture myself using a jigsaw. Strangely, my wife still hasn’t forgotten that.