Installations should not damage the building envelope

Hello and good day,

we are currently looking for a suitable construction contractor who builds ecologically.

It is also important to us that the envelope is not pierced/damaged for the installations and then has to be sealed again afterwards. We cannot imagine that it would be as tight as the "original."

Is this only feasible with an installation level, or are there other possibilities?
One provider responded to the question about an installation level that they work with an electrical pre-installation in empty conduits.

What is meant by this, and is it recommended?

I assume that you prefer or have already looked into timber frame construction or something similar? Normally, the standard includes a vapor barrier/vapor retarder directly behind the drywall, which is, of course, penetrated by every cable and every socket.

That is why airtight boxes are used at that point and the cables are routed through conduits that are also airtight. That is probably what the mentioned provider meant; they likely do not offer an installation level.

An installation level usually involves an additional charge. In this case, another layer is added in front of the standard wall, which, for example, is filled again with mineral wool. This means you have another 6-8 cm before the actual vapor barrier/vapor retarder and do not have to worry about airtightness. With our provider, this was already included in the standard exterior wall. Optionally, we could have the layer blown with cellulose for the "ecological conscience" .

I would definitely recommend an installation level, especially because after construction you can easily add more sockets during the interior finishing if you forgot some.

And on the subject of ecological building: Please take a close look at the materials used. Wood fiber insulation and cellulose sound totally ecological, for example, but the problem is fire protection, which is why these materials sometimes have to be treated with boric acid etc., and thus are not necessarily more ecological than a fired brick .

Hello Uwe82, yes, that's right. They are prefabricated house providers.

What advantage is there besides the easier installation of the boxes during construction, or what disadvantages are there if you do without them?

Are the seals of the places that are pierced really tight?

When installing decentralized fans, you pierce the wall in any case, whether in the installation level or not, or am I wrong?

Best regards

Are the seals at the points where penetrations occur really tight?

That is exactly the question. However, since sometimes a triple-digit number of boxes are installed, the risk of leaks is relatively high. That may not be a problem in individual cases, but could become an issue over time if something loosens, e.g. due to movements caused by plugging and unplugging connectors. I didn’t want that. And nails or screws in the wall may also potentially penetrate the barrier. That is usually not a problem. If they are left in, it generally remains sealed. But the holes would have to be properly sealed again if the screws are removed.

If you install decentralized fans, you pierce the wall in any case. Whether there is an installation level or not, or am I wrong?

Absolutely correct, but that is a significantly smaller number. There are also plenty of other things that will break through the barrier (empty conduits for electric shutters, exterior lamps, intercom systems, etc.). But the fewer there are, the lower the risk and the more effort one is usually willing to invest in sealing. With 100 empty boxes, this willingness could suffer. Above all, the empty conduits have to come out somewhere on the inside again...

But here, a lot of peas are being counted. Of course, a proper sealing using a vapor barrier is important. This work is tedious and can be done well or poorly. I would find it much more important to actually check it afterwards. The nail in the wall certainly does not damage the entire envelope of the house. In theory, the vapor barrier is damaged, but this is practically not noticeable, as there are many many spots that cannot be sealed 100% and therefore weigh much more heavily.

The decentralized ventilation systems can certainly become a problem, even if one wants/must comply with KfW standards. The cross-sections are simply relatively large. Calculate the perimeter of the ventilation holes and how many small nails you can hammer into the vapor barrier for that.

But here a lot of peas are being counted.

A lot of peas also make soup for many people, that's the point. If you insert empty conduits into airtight hollow wall boxes, you'll never get those things 100% sealed, just like when the empty conduit has to go through the barrier again at the bottom on the floor. This might already cause four leak points per box, because conveniently you have two empty conduits per box.

With an installation level, I have these problems less during the construction phase and afterwards, even if I sometimes have to drill holes for hollow wall anchors to hang heavy things. After careful consideration, I wouldn't build without an installation level, because the risk would simply be too great for me if I had to think about the barrier at all those points in sum.