Electrical routing space of about 2 inches behind wall panels?

[Suhagg]

Peeked at a villa under construction and there they had about 2 inches of installation space behind drywall and OSB. The space was completely empty without insulation and was studded at cc 60.

Is it normal for it to look like this? I thought it usually had insulation in this space but maybe it's completely unnecessary since it becomes still air here that also insulates.

 

[hempularen]

The usual practice is probably to insulate there as well.

 

[noone70]

were they like that in the internal walls or/and external walls

 

[Suhagg]

were they like that in the partition walls or/or outer walls

Outer walls. In the partition walls, there was only the framework and insulation. No vapor barrier to consider. It might not be noticeable once everything is in place, but when you tapped on the wall panels, it felt like a drum. Resonance sound or hollow feeling. But as I said, it might never be noticed.

 

[Mikael_L]

I am insulating that space, but I allow myself a little sloppiness right there. Especially around pipes and junction boxes, where I don't bother to fuss too much.

 

[BigGitt]

If it is insulated, it is better. It's not about that many kronor. However, sometimes it is better to avoid insulating. However, it depends if the outer wall is made of 70mm studs. Which is rare.
Once had it uninsulated. Noticed strong draft from electrical boxes.
But maybe it doesn't matter?

 

[Suhagg]

It's gypsum, OSB, studs, plastic, etc., etc. from the inside.
There shouldn't be any moisture or air entering this space.

 

[Mikael_L]

From the inside, it's gypsum, OSB, studs, plastic, and so on.
There shouldn't be any moisture or air entering this space.

Or maybe the opposite ...
Both air and moisture probably get in there.
+ you are enclosing it as well, since it's hardly air or moisture-free there when you screw on the OSB, right?

 

[BigGitt]

It's gypsum, OSB, studs, plastic etc. seen from the inside.
Neither moisture nor air should get into this space.

Yes. You're building in the moisture.

 

[noone70]

No moisture is being built in, you only have plastic protection that prevents moisture from coming in from the outside. On the inside, there is no barrier, so you are not building in the moisture.

 

[b8q]

However, the moisture you want to prevent comes from inside the house, not outside, and the moisture barrier prevents it from condensing inside the insulation in the wall.

 

[noone70]

The important thing is that there aren't two moisture barriers with insulation in between. That would trap the moisture between the two layers.

 

[Mikael_L]

From the inside, it's gypsum, OSB, studs, plastic, etc., etc.
There shouldn't be any moisture or air coming into this space.

Sorry. I was just unnecessarily precise... :blushing:

You don't need to worry whether you insulate there or not. If insulated, I would suspect that your wall would be a bit more energy-efficient. In an air gap that's 45mm wide, I believe the air moves by convection, meaning it does not insulate like stationary air does.
But you won't have moisture problems, as long as you don't have diffusion-tight further out in the wall.

I was being a bit sarcastic, since there will obviously always be both air and moisture in all parts of the wall. But the relative humidity (rH) will be very low just behind the plastic (facing the outside, that is). Then rH slowly rises the closer you get to the outside (at least when it's cold outside).
The rH on the inside of the plastic is relatively high and is largely determined by how good your house's ventilation is.

 

[Mikael_L]

The important thing is that there aren't two moisture barriers with, for example, insulation in between. Because then you lock in the moisture between the two layers.

And the same applies without insulation as well. The insulation neither improves nor worsens this.

 

[Suhagg]

This space was exactly 28mm.
If I want to insulate this space for some extra insulation and soundproofing, what do I choose?
A 45a would be too compressed, right?

Pre-cut standing electrical/nail battens 28 mm on the inside of the outer wall
(simplifies electrical and pipe installation and to avoid unnecessary
holes in the vapor barrier).