Adding a bathroom in the attic afterwards - costs?

If you don’t need the bathroom right now, I wouldn’t do it yet.

But prepare all the pipes:
Wastewater pipes for toilet, shower, sink. Depending on whether it’s a concrete or wooden ceiling in the attic, possibly have them pulled to the expected location already. It should actually be unproblematic because you’ll have to have pipes pulled up anyway for the ventilation of the bathroom below.

Water pipe and standing water should be unproblematic if you use a circulation pump. Then there’s actually nothing else. I wouldn’t want to do without it in my own new build anyway.

Basically, it will be more expensive later, because a small construction measure means more hassle and extra trips etc. But since you’re having everything done through the general contractor, it could be significantly cheaper later if you find a tiler and plumber from the village who also installs the tiles and sanitary fixtures from the hardware store for you.

Nice topic. And we are currently in the process of expanding in the attic. Planned now: bedroom, office, no more home studio. For training, we still need a kids' room. But the bathroom is out.

Back then, we pre-installed the pipes, so we could have realized the bathroom quickly. However, we decided against it due to the costs, etc. We already have a very large bathroom upstairs, and maybe the oldest daughter will move up there. Showering was not really planned anyway, and for the rest I just go downstairs and save thousands of euros.

A few suggestions in advance, maybe it helps:

- have the window installed right away if the location of the bathroom is already fixed. I didn’t think of it anymore and took it out. Back then it would have cost us nothing. Now it would easily be €3,500.00 - €5,000.00, despite pre-installation. And we didn’t want a fan. Carefully consider the exact room layout regarding electricity, shower, toilet, sink and especially the partition wall, etc. Next door the planned wall would now be in the French door… that was probably a no-go.

- Flooring? We are laying parquet. Now I’m considering putting a cork strip in the bathroom area or new drywall wall so I could remove that area later to lay tiles. If the project unexpectedly becomes current again. Parquet in the bathroom with kids is probably not so great.

- Do you want craftsmen in the house again? The dust & dirt, etc.? My wife is already freaking out, and so far only drywall and electrical work have been done. Plastering, etc. is still to come.

I think the price is about the same, unless you arrange something directly with the craftsmen on site. They’re there anyway, material too, and are usually open to suggestions. I won’t say more about that.

Not an easy decision. Do you really need the bathroom? Do it at once with the above sentence, it won’t get cheaper. Otherwise, consider and lay pipes, get the window in.

Good luck

In the drawing where the bathroom is then included, some really thick walls are drawn, and all the sanitary facilities are installed exactly on this wall.

So far, it was only about realizing the bathroom later. Now you write as if you want to postpone the entire floor plan of the upper floor with all interior walls to some time (?)

Aside from the craftsmen and the dirt, did everything else work out? Was the decision to build it only 15 years later a good one?

For us, the decision was right; we were building the house as a couple and only realized the attic when the children were old enough to sleep on their own floor, and we moved into the attic. For us, the attic was a large room for a long time, only separated by the stairwell. We did the rest during the finishing phase. We had previously thought about where the toilet, sink, and shower should go and had the pipes laid accordingly and also had the windows installed right away. If, for example, no children had come, we wouldn't have needed the bathroom in the attic.