Single-family house, single storey, knee wall, upper floor window

Hello, good evening!

I would like to thank all the active members and moderators here once again, because as a silent reader I have already received some good tips. However, we are currently pondering things that are not, at least for me, discernible on the WWW. The following: Planning a single-family house with very tight specifications Max house footprint: 121m2 Single-story Lower Saxony

We want a dormer on one side and narrow windows in the knee wall on the other side, if possible. Unfortunately, we encounter different statements from architects, so I would like to ask the following questions:

Which parameters still play a role in the calculation of the upper floor so that the best possible use of the knee wall height can be achieved. The Lower Saxony building code only states full storey from 2.20m clear height, 2/3 of the house footprint. Now I also know that the thickness of the gable outer wall is not included in the calculation. Are there any other things that count in favor of the upper floor area, such as stairwells, interior walls or the like? From when are narrow windows on the roof slope side in the upper floor possible, or even impossible in the case of single-story?

If further information about our project is needed in this regard, just write!

Sorry for my amateur construction terminology!

Regards Tom

It’s about the interior, if I remember correctly... stairs etc. pp. don’t matter. It depends a bit on what kind of windows you want... so a window in the stair area works – normal windows are difficult... what’s the use of a window you can’t look out of. Do you have 121 m² of floor area for the house or 121 m² of buildable area? A tip is always to add a "Wintergarten" or something else on the ground floor and thereby "artificially" increase the area on the ground floor. However, that somewhat conflicts with your 121 m². Do you have specifications for other heights? (ridge, eaves etc. pp.)?

Hey!

121m2 as plot ratio 1, for house floor area. However, we need every m² of room area, because of many children, therefore no conservatory. We really like the slightly deeper narrow windows, so we would prefer them to skylights, compared to the dormer, on the sloping roof side. There are no readable regulations for ridge, eaves, knee wall. Unless some Lower Saxony general clause says otherwise. Only single-storey and max. two units per house. Now I would like to know how to optimally use the 2/3 above.

Best regards
Tom

Regarding the windows in the knee wall: I also wanted them for the appearance. Disadvantage: with a low knee wall, you have about 30 cm of parapet height with 70 cm window height (rough construction measurement). Above that then the lintel... That leads to about 130 cm knee wall. The window would then be fixed glazing for safety reasons. What do you gain in a normal room? Less space for furniture. Additional light source in addition to another window. Otherwise nothing. We wanted it opposite the staircase in the gallery, for the view - we don’t need space for closed rooms since it’s only the two of us. My advice would be: don’t do it and rather build usable space! Regarding the single-story: achieved single-story with about 160 cm knee wall. 120 sqm buildable area results in about 80-90 sqm living area in a timber frame house, the same floor area upstairs. 160 cm knee wall is almost fully functional living space. Children can walk up to the wall, and with a wardrobe standing against the wall, even an adult can. Then you can also set the window bands higher, so that children, but also when sitting, the view outside is guaranteed. Since you usually don’t stand directly in front of a window, the lintel isn’t disturbing and generally doesn’t obstruct the view outside. The view itself is slightly directed downwards, not towards the sky. In that respect... with 160 cm... better than skylights!

Actually, the floor area ratio indicates the area that may be built upon, including access paths - but I could be wrong. Often there is still a 50% allowance for access paths; however, the terrace, for example, counts as part of the house. The longer the house, the higher the knee wall can be (but everything in between will also be narrower).

That's why I want the knee wall as high as possible.
A height of 130 would actually be too much like a submarine.
The narrow window in the knee wall is only meant for the bathroom, above the bathtub. I just don't like having to resort to roof windows.
The question now is, since we actually come to about 81m2 upstairs, how can this still 'grow'. Do you calculate 2/3 of the gross area downstairs and take the result for upstairs as the net area, meaning you distribute the result over the total floor area of all rooms upstairs!? That way you would exclude the interior walls as well as the exterior walls.
And are there other possibilities, like the stairwell or the broom closet (just thinking aloud), to expand the upper floor area!?
What do you mean, Yvonne, by using floor-to-ceiling windows with the 160 knee wall? And does BeHaElja have (or not) a dormer on the opposite side?
Exactly, the floor area ratio-2 then indicates how large the accessory buildings (garage, access paths, etc.) can be. Those would be your mentioned 50% exceedances.
For the terrace, I would consider grass! Otherwise, it won't add up!