ᐅ Planning a Guest Bathroom in a New Build – What Is the Minimum Size? (Building Standards?)

We also had a small guest toilet in our first self-built house. About 1.20 x 1.80 meters (4 x 6 feet), the door opened outward. It works well.

Thanks for the explanation of terms, 11ant. A general contractor has almost been found. We expect to decide between two offers next week.

We are planning the semi-detached house together with our neighbors. However, they are planning a shower bathroom on the ground floor and therefore need more space anyway. We will forgo the shower and be content with the smallest guest toilet imaginable.

The plans are not professionally drawn yet, and I actually wanted to spare everyone here my amateur sketch from Roomsketcher. Just for orientation, here is the draft for the hallway corner plus guest toilet. Roomsketcher only provides measurements for a fee.

What you see should be taken with caution:
- Guest toilet measuring 1.95 x 1.00 m (6.4 x 3.3 ft), door 76 cm (30 inches), position of toilet and sink not final
- Staircase width 2.13 m (7 ft)
- Entrance door on the right
- Door to the living area on the left
- Door to the utility room at the top
- Door swing directions are not final and have not yet been discussed with professionals
- Sizes of hallway, bathroom, and utility room are not final
- Bottom wall is the neighbor’s wall

Basic information: The conditions on the plot are complicated. The house will be small (105-110 m², 1130-1184 sq ft). My main concern here is to find out whether a bathroom must have a minimum width.

T-i-m-m schrieb:

The question is whether you can freely decide on the room dimensions in a new build or if you have to follow a certain DIN standard.

There is no DIN standard specifying how large a room should be; there are guidelines for clearances. For example, 60cm (24 inches) in front of a toilet, 25/30cm (10/12 inches) beside it, and 20cm (8 inches) beside washbasins.

T-i-m-m schrieb:

we want to keep non-living rooms small and give the gained space to the living areas instead.

The relationship is missing here! I agree if you reduce a 3sqm (32 sq ft) toilet to make a rather small living-dining room (or whatever) more practical to furnish. But if, for example, 50sqm (540 sq ft) are available for the open-plan area, you can easily take away 1sqm (11 sq ft) from that to make a 2sqm (22 sq ft) toilet more comfortable.
Therefore, you cannot just give fixed dimensions outright.

T-i-m-m schrieb:

Conclusion: 1 meter width and 2 meters length are more than enough.

90 x 130cm (36 x 51 inches) can also be sufficient.
But those are finished dimensions. On drawings, you deal with raw structural dimensions.

There is also the difference between a slim young man standing while urinating who doesn’t need much width next to the toilet versus a visiting overweight mother-in-law who needs more space next to her for hygiene purposes.
Some people are fine with a small hand basin, others find that inadequate.
Do you expect many children washing hands together, or are you just two adults often using the toilet alone?

T-i-m-m schrieb:

Are you not allowed to plan a 1-meter-wide guest WC in a new build?

See above.

T-i-m-m schrieb:

In our case, the door would be on the short wall, the toilet opposite the door, and the washbasin on the long wall.

Better to have the door on the wider side.

So you see: the topic of room sizes is very complex. It only takes a small concession not to use the full 2 meters. I would always plan something like this as a whole floor, as part of a house.
If you present your entire design here for discussion, you will gain valuable feedback 😉

T-i-m-m schrieb:

What you see should be taken with caution:
- Guest toilet measuring 1.95 x 1.00 m (6.4 x 3.3 ft), door 76 cm (30 inches), position of toilet and washbasin not final

There aren’t many other options here. However, you will have the washbasin right in front of your face while sitting, and there is no freedom of movement when standing up.
The room as such (toilet) is very poorly usable.

T-i-m-m schrieb:

- Staircase 2.13 m (7 ft) wide
- Entrance door on the right

Apparently, the other semi-detached house is located at the bottom of the plan.
The design of the upper floor is interesting given this staircase position!

The WC door definitely needs to open outward, and the sink should be moved further toward the top of the plan. As it is, using the WC is really inconvenient.

Looking at this type of hallway, I see about 5 to 6 square meters (54 to 65 square feet) of walking space without any practical use. There’s no real place for cabinets or similar storage. I would also recommend posting the overall floor plan. However, please do this in the section https://www.hausbau-forum.de/forums/grundrissplanung-grundstuecksplanung.237/ while observing the guidelines at https://www.hausbau-forum.de/threads/grundriss-planung-unbedingt-vor-beitrag-erstellung-lesen.11714/.

In my opinion, it would be better to make it wider and therefore shorter. We have 1.25x1.40m (4.1x4.6 ft), with the toilet along the shorter side. With a reasonably sized sink, 1 meter (3.3 ft) in width would be too tight for me...

Especially since, as the electrician nicely put it to me: "You have three women at home, so this will be your bathroom..."