ᐅ Basic Questions About Floor Plan Design (Wall Thickness, etc.)

Created on: 16 Dec 2018 06:52
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Didadu
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Didadu
16 Dec 2018 06:52
Hello,

we are at the very beginning of planning a floor plan for a single-family house. We have not yet had any discussions with a builder or architect. However, before these talks, we would like to create an initial design to see if our ideas are generally feasible in reality. It wouldn’t help to plan with overly thick concrete or drywall partitions, as this would create a very distorted impression of the floor plan. Our online research and various guides have not provided us with a satisfactory result. We understand that every house is unique, but we believe there must be a standard or common practical guideline.

What “standard” thicknesses for exterior and interior walls should we use in our designs? How much wall length do we need for a 90 cm (35 inch) wide door or window? Do we need to allow extra space in the wall for door or window frames?

Best regards, hoping for helpful answers.
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kbt09
16 Dec 2018 07:07
If you read through some threads in this forum section where you started your own thread (https://www.hausbau-forum.de/forums/grundrissplanung-GrundstĂŒcksplanung.237/), you will find many floor plans from which you can learn.

Generally speaking:
Exterior walls 36.5 to 45 cm (14 to 18 inches)
Interior walls 11.5 to 24 cm (4.5 to 9.5 inches)
On both sides of doors (consider the handle when the door is opened at 90°) about 10 to 12 cm (4 to 5 inches).

Your own apartment can also provide many useful measurements, both dimensions that frustrate you and you would like more space in the future, as well as those you find satisfactory. You can easily walk around with a tape measure for this as well.

The most important first step is to create a written room program, ideally noting what you want to fit into each room. If you have existing furniture or items, note their measurements too. You can cut these pieces out of paper to scale.

Then, once you have the room program, start sketching. You can move the cut-out furniture pieces around on the sketches to get a good sense of whether the room sizes work.
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Didadu
16 Dec 2018 09:28
Yes, we have used floor plans as a reference, but unfortunately most of them either lack dimension details or are not to scale (exterior walls with a thickness of less than 25cm (10 inches)).

Our own apartment cannot be used as a reference because it is a very old building, with some walls insulated and others not insulated at all.

However, we can use your information as a guideline, thank you!
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ypg
16 Dec 2018 10:43
Don’t focus too much on exact wall measurements. First, even when working with design software, as a non-professional you should stick to rough sketches. Second, walls will still be covered with plaster.

Third, it is the responsibility of professionals—such as draftsmen and architects—to determine the required wall thickness. Wall thickness also depends on the type of bricks or wall materials used. For example, if a load-bearing wall is needed, a 12 cm (5 inches) wall will not be sufficient.

To create a room where a 3-meter (10 feet) wardrobe is planned, an exact interior dimension of 3 meters (10 feet) is not enough. Adding about 10–15 cm (4–6 inches) to your measurements will give a more realistic result.

As mentioned before, stick to rough sketches and mark walls with furniture. Architects and draftsmen are experienced and understand that a house requires space for furnishings as well as door frames.
11ant17 Dec 2018 18:54
Didadu schrieb:
It’s no use planning with bunker-like or paper-thin walls,

Actually, plan with paper-thin walls (just simple lines, since as non-professionals you won’t be able to tell which “type” of wall is needed where), and add about 1.20 m (4 feet) to the total width and depth of the house as a safety margin.
ypg schrieb:
To create a room for a 3-meter (10 feet) wardrobe, an internal dimension of exactly 3 meters (10 feet) is not enough.

You have to account not only for plaster and baseboards but also for tolerances in measurement, flatness, and perpendicularity. Don’t think in single centimeters.
Didadu schrieb:
How much wall length do we need for a 90 cm (35 inches) wide door or window (do we also need space in the wall for door/window frames etc.)?

Several dimensions need to be considered here. Starting with the example measurement of 90 cm (35 inches): 87.5 cm (34.5 inches) is the nearest "standard dimension," which with the joint gap results in a rough opening of 88.5 cm (35 inches). The interior door frame (jamb) is usually around 6.5 to 7 cm (2.5 to 2.75 inches) per side, covering roughly half the wall thickness and thereby reducing the clear opening. A light switch requires a clearance of about 12 cm (5 inches) from the frame’s midpoint, and lintels are generally 15 to 25 cm (6 to 10 inches) wider than the openings. But don’t memorize these details, especially not the half-centimeter increments—I’m just sharing them to give non-professionals some insight.

ANY plan that would work based on “precise calculations” alone simply DOES NOT work in practice!

So don’t worry about the “ones” digit in centimeters; feel free to think in more familiar steps of 10 or 5 centimeters (4 or 2 inches) for non-professionals—and always round tolerances up generously to about 5 cm (2 inches), even if the real value might only be 2 cm (0.8 inches). A professional planner can convert this into an eighth-meter grid if needed.

With that in mind, you can roughly calculate interior walls as 20 cm (8 inches) thick and exterior walls as 40 cm (16 inches) thick—without obsessing over exact measurements anywhere, it will all add up in the end.

Also, take advantage of your non-professional status and consider rough sketches “good enough.”
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ypg
17 Dec 2018 19:51
11ant schrieb:
Yes, plan with paper walls (just simple lines, since as non-professionals you won’t be able to tell which “type” of wall is needed where), and simply add about 1.20 m (4 feet) to the total of the room widths for the overall house width and depth.

I have to disagree with you as an active drawer both on graph paper and on screen – THAT approach doesn’t work. You can’t just remove something in the middle and add it on the outside when more than one wall is involved.