ᐅ Survey on Gable Roof Knee Wall Height

Hangman schrieb:

Obviously not:

If necessary, the exterior walls on the upper floor might need to be better braced, since the upper floor/attic ceiling no longer serves to absorb tensile forces. This probably also depends on the position of the interior walls as supports, but that’s what structural engineers are for.

I wouldn’t call 2.65m (8 ft 8 in) a knee wall, at least not in the traditional sense. We built ours this way as well. But to me, that’s two full stories. No idea if there’s an official definition for that.

Well, I meant, for example, 2.25-2.3 meters (7 ft 5 in - 7 ft 7 in). That would then be 2 meters (6 ft 7 in) to the top edge of the window with the roller shutter box. OK, but actually not.

bauherr2019_he schrieb:

I just wanted to ask out of curiosity if there are any homeowners here who have built a gable roof but deliberately kept the knee wall lower than the maximum possible height?

Yes, we have. According to our development plan, a single-story building is required. Many families with two children (or just because of the look – many prefer the appearance of two stories) stretch the limits with an urban villa style, knee walls of around 180cm (70 inches) or so... We have 1.30m (51 inches) inside. That wasn’t difficult for me since we didn’t urgently need the space upstairs and actually preferred having less space there. So now the bed is placed beneath the sloped roof, with a roof pitch of about 22 or 26 degrees (I don't remember exactly). The dressing room is a bit restricted, but still offers more freedom of movement than others with their narrow dressing corridors. With the low roof pitch, we also didn’t fully maximize the height.

Hangman schrieb:

The traditional building style here has no knee wall, which is why a maximum of 75cm (30 inches) on the outside and a gable roof with a pitch of 35-45° is specified.

I like that and it’s my preferred building style: you get a bit more floor area on the ground floor, but still have the option to use the attic space with nice rooms and real windows. Almost anything is possible.

Deadree schrieb:

In our case, the wall goes up 2.65m (8 feet 8.5 inches).

That would be a two-story building. Unfortunately, and this probably applies to you, lot sizes are getting smaller, so the floor area ratio limits the building footprint to such an extent that the roof slopes can’t be compensated by the base area. Therefore, you have to increase the knee wall height in order to reach the required square meters, even if it’s only possible by having real headroom clearance.

bauherr2019_he schrieb:

Sorry for the silly question 😀, but what exactly do you mean by that?

I’m not to blame for you still asking a silly question ;-) (in the quoted post, I mentioned the title of the explanation, which you have to look up yourself due to the forum rules here). @face26 has already correctly summarized essential parts of it. The knee wall height creates a dividing line similar to a high jump bar: facade windows in the knee wall must duck below it, roof windows have to jump over it and might then only illuminate the top of your head. Windows positioned in height on either side of this dividing line force a dormer on the eave sides, and thus an eave and ring beam opening, or otherwise are only possible on the gable sides. The “window dividing line” knee wall is best set, considering the view, at a height where a “beam in the eye” is not disturbing: so low that the roof window sill is not at chin height (or so high that only children up to about third grade can look out from the facade windows).

Tolentino schrieb:

Is there technically any objection to going above 2m if allowed?

Similar to the window dividing line, there is a tipping point for the proportions of the cross-section—that is, the gable-parallel walls of the attic—between the positively perceived effect of high straight sides and the impression of “cut-off corners.” In my opinion, up to a knee wall height of about 1.80m (5 ft 11 in), the impression of a high knee wall prevails, but above that it tends to feel like a ceiling pushed up into the attic or a lowered roof slope resembling a cap pulled over your face. Unless you can avoid this with a roof soffit running up to the ridge. However, that can lead to very tall rooms. For roof pitches around 35°–40°, I recommend either a combination of a knee wall 100 to 140cm (39 to 55 inches) high with a ceiling, or alternatively an open ridge with a knee wall 180 to 220cm (71 to 87 inches) high paired with a relatively shallow gable roof of about 20°–25°. Unfortunately, mansard roofs hardly ever appear in the minds of garden gnome-like members of the local planning boards responsible for zoning plans almost everywhere.

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11ant schrieb:

The "window apron" knee wall is best positioned in terms of the view at a height where a "beam in the eye" is not disturbing: that is, low enough so that the roof window sill is not at chin height (or high enough so that children up to about third grade can look out of the facade windows).

Excellent and practical description; I will remember it exactly like that. To add variety to this "window apron," window arrangements can combine a full-height knee wall window with a roof window. There remains a single line, of course, but the windowsill is eliminated.

The room’s appearance can also be influenced by boxed-in areas, for example, for storage or built-in furniture.

In some development plans, it is possible to extend a room with dormers. This then depends on the described length and width proportions.

ypg schrieb:

I didn’t find it difficult since we don’t urgently need the space upstairs and actually preferred having less room up there.

Honestly, I think with a height of 1.30 m (4 ft 3 in), you are hardly limited at all when it comes to placing furniture. Almost everything fits underneath except for a large wardrobe. But for that, I still have other walls available in the rooms ;-) Our walk-in closet might be like the narrow corridor you described, but it doesn’t have any sloped ceilings because it’s located on the gable end.