Enough daylight in the children's rooms?

Hello,

But one more important question for the experts: We already have our "building permit" (here: approval exemption with development plan). Are window changes (e.g. for structural reasons) simply feasible without having to involve the building authority again?

It depends ...

The exterior shell – and with it the arrangement/size of the windows – is part of the building permit. A few centimeters larger/smaller do not require an amendment. For additional double casement windows, it depends on how the case officer slept the night before ;)

Rhenish greetings

@ BeHaElJa, ypg and Bauexperte: 6.5 cm widening per window side should not be a problem then :-)

Hello,

The design calls for a good 2.3 sqm of lighting area per room; legally required is ⅛ of the floor area. So the rooms are more than bright enough. I rarely understand the whole discussions about - comparatively - large window areas in relation to the floor area.

I would only install double casement windows if all other options are exhausted.

Rhenish regards

We just have no idea if the planned window areas are sufficient. It is our first and hopefully last house. Of the raw building dimensions (2.3 sqm), not the full 2.3 sqm of pure window area remain. At least the window frame is deducted. And then even just 13 cm wider windows would already be almost 15% more light area.

So, yesterday I was able to talk to the window manufacturer. A window widening (3-pane glazed, floor-to-ceiling, single sash, with fixed lower light) would be possible, but he could then not provide a warranty for the lasting functionality. The reason is that the windows would simply become too heavy and pull down too much when opened. The 1.13 m rough construction width (= 1.10 m finished width = 0.85 m clear light width) is the maximum for him.

What experiences have you had with this?

What he says does make sense - triple-glazed windows/doors are incredibly massive and heavy. You might consider a fixed part and widen the windows a bit more, if that is possible. The formulas - 1/8 of the room area should be window area, or 20% refers to the raw construction measurement.

So how about two wings? Then the triple glazing becomes lighter... despite the size...

Maybe you could consider a fixed part and widen the windows a bit more, if that is possible.

Good idea, but unfortunately that is not feasible for us. Due to our floor plans and elevations, at most the additional 13 cm suggested by Manu1976 would be possible.

The formulas – 1/8 of the room area should be window area or 20% refers to the raw construction measurement.

1/8 is 12.5%. Or is it 20% after all?

Well, how about two sashes? Then the triple-glazed windows would be lighter... despite the size...

With double-sash windows with a mullion, however, too much light area is lost due to the window frame.

@ all: Thanks for your help! But we will probably have to stick with the previous planning.