ᐅ Which type of hollow wall boxes are the right choice?

Hi,
I am currently planning my interior finishing.
Now I am wondering which flush-mount boxes are the right ones:

When should I use airtight flush-mount boxes and when are “normal” ones sufficient? Or can I generally skip the airtight ones?
My wall structure (interior wall) consists of 10/12 cm (4–5 inches) KVH framing + 15 mm (0.6 inches) OSB + 12.5 mm (0.5 inches) drywall – OSB and drywall obviously on both sides.
The exterior walls have a 6 cm (2.4 inches) installation cavity + 15 mm (0.6 inches) OSB + 12.5 mm (0.5 inches) drywall.

With this wall setup, would you generally recommend boxes with a depth of 61/62 mm (2.4 inches) or are 47 mm (1.9 inches) boxes sufficient?
I tend to prefer the deeper boxes, but am I overlooking any disadvantages here?

Thanks and best regards
Chris

You should always use the deep boxes. I wouldn’t use the shallow ones now. Most electricians prefer the deep boxes.

Basically, you don’t need airtight boxes; these are only necessary with Poroton blocks because of the air chambers in the blocks. I foam-insulated the boxes anyway, so they are airtight regardless.

But you also need the cavity boxes in orange.

Airtight boxes should always be used whenever you penetrate an airtight layer, for example drywall on an external wall. They are meant to prevent drafts. Whenever possible, use deep boxes. The electrician will appreciate it, and you will have the option to retrofit devices like Shellys later on.

Hi, thanks for your answers. I will focus on the ~61mm (2.4 inches) deep boxes. Since I am only working indoors (installation level or interior walls), the airtight version is not necessary.

One thing to consider in special locations is multimedia boxes, like the Kaiser 1068, which allow you to incorporate some electronics inside. I placed these next to the indoor door opener station as well as in other locations relevant to the door opener. A PoE-powered SBC fits inside, and the display is essentially recessed into the wall.

If you are 100% sure that the vapor barrier is protected outside of the installation layer (or if you don’t have one at all because the OSB board is designed to be airtight/vapor-retardant), you can use standard electrical boxes.

But do those extra 30-40 cents per piece really make a difference? I would always go for the airtight ones, as they also serve well as a mini dust barrier.

And only use deep boxes – even those are, speaking as a layperson, quite tricky to wire neatly. I would have been seriously frustrated if I had to connect the sockets in standard boxes.

Electrical boxes designed for electronics could be an option if you want to install flush-mounted devices (or Wago connectors, etc.). However, you need to make sure they are mounted so that no beam is in the way – the electricians from Genius at my place managed to install several in a way that made the electronic components unusable...