ᐅ Exterior Wall for KfW 40 (+) Standard: With or Without External Thermal Insulation Composite System (ETICS)?

In our old house from 1995, we installed better sound insulation because of the nearby Tegel airport, using thicker drywall boards under the roof.

In @pagoni2020’s case, I would suggest constructing the open roof structure as follows: roofing underlay membrane, an air gap, 40mm (1.6 inches) mineral wool insulation, vapor barrier, 15mm (0.6 inches) blue drywall panels, and possibly acoustic panels to reduce echo. The beams should extend about 10-15cm (4-6 inches) beyond the panels. Above that, insulate the roof as originally planned.

@pagoni2020

You can take a wooden beam ceiling as an example. With exposed beams, achieving soundproofing certification in a multi-family building fails.
There is a lack of insulation material for the higher frequencies (see typical fiberglass used in speaker construction) and a bending-soft shell of springs underneath.
Assuming we are talking about approved standard systems.

If you subjectively prioritize this and do not want to add a lot of mass, a combined roof insulation would be possible, such as a wood wool board or wood fiber concrete panel plus PIR/PUR foam.
This way, the rafters remain fully visible in height.

It is always necessary to check the water vapor diffusion equivalent air layer thickness, since there will be a visible sheathing on the rafters on which the vapor barrier lies.
Wood wool board under PIR could already fail this requirement.

@Nida35a

You cannot apply another insulation over mineral wool due to the water vapor diffusion equivalent air layer thickness. The new material must have an equal or better Sd value. However, the sound insulation might be improved by the moisture retention in the mineral wool,...

Franke86 schrieb:

Is this good or bad now XD

JEHOVA! 😎

But today is Friday, so grab the popcorn.

ypg schrieb:

What confuses me: is 18mm (0.7 inches) insulation enough for your KfW40?

Franke86 schrieb:

According to the developer, it is sufficient. I also have a colleague who built with KfW 40 plus using the same wall structure.

That’s enough. For KfW 55 we got by with 16cm (6.3 inches) insulation at thermal conductivity 0.032 W/(m·K) on sand-lime brick. KfW 40 isn’t much further. Since the proposed brick already has insulating properties, that seems plausible.

ypg schrieb:

It’s just plastic! ETICS is polystyrene with all its pros and cons. You can’t even drive a nail into it.

ETICS is not automatically "plastic," and you have to consider both sides of the story. Have you, for example, avoided plastic INSIDE?

What nails are you planning to hammer into the facade? Nails are outdated; you screw instead. There are excellent ETICS anchors for that. At least in "plastic ETICS," I can say they hold everything from lamps to mailboxes without issue. Heavy items are fixed with wall anchors or prepared during construction by using mounting blocks.

I have a sun sail fixed through ETICS into the intermediate ceiling using two base plates and thermally separated wall anchors. It holds even with winds up to force 8. Works fine.

WilderSueden schrieb:

Although you can also get solid masonry. Personally, I like that concept better. Being able to easily hang a mailbox and outdoor lamp everywhere is a nice bonus.

ETICS with polystyrene is obviously the cheapest option, but that means you have polystyrene on your wall. I find that absolutely outdated. And the alternatives listed by @nordanney are somewhat more expensive than polystyrene.

EPS is the insulation material of today and, for the foreseeable future, as well. If you like statistics, feel free to look it up.

Don’t get me wrong; I also find monolithic construction quite appealing and initially wanted to build that way, but for anything beyond basic energy saving regulations, it’s not practical. The bricks get thicker, crumblier, or filled (each with pros and cons). Anything above about 36.5cm (14 inches) of aerated concrete or clay blocks is economically uninteresting.

Energy standards are getting stricter, not looser. In my opinion, monolithic construction is not the future.

WilderSueden schrieb:

Polystyrene is garbage that in the end can only be burned because it’s useless for anything else. Whether it actually lasts 50 years is another question. Monolithic masonry lasts until demolition.
And the outer shell is completely independent of the heating technology 😉

When after 50 years the ETICS facade needs replacing, you tear it off and renew it with the then state-of-the-art and sensible insulation material.

What do you do in such a case with a monolithic wall? Add cladding. Have fun living in the castle.

ypg schrieb:

That’s the point: total inflexibility for creative people!

I’m still looking for inspiration for facade design based on nails. 🙂

Until then, your comment sounds quite forced to me.

ypg schrieb:

Okay then... great, but no quality. It lowers the quality of the house!

Phew, don’t tell that to neighbors with their 2-3 million € houses, all exclusively built with ETICS (with plastic).

Or the countless renovation projects, which without EPS’s unparalleled insulation effect would be left as bunkers or would have to be demolished.

Bookstar schrieb:

Unfilled clay blocks are not only bad for the outside. Noise also transmits brilliantly inside the building. You get nasty structure-borne noise, which is why it’s banned in multi-story buildings, among other things. There certainly are people like Zaba who tolerate it, but from a technical perspective it’s a bad choice of brick. Unfortunately, I was persuaded by the developer to use it too. And I know so many now who would never build with this block again.

Filled bricks and peace and quiet.

I find that a bit strange since the wall is separated by a floor slab.

However, in monolithic construction a thermal bridge lurks there (floor slab). I believe you place a few centimeters of XPS insulation in the formwork to reduce the cold bridge into the intermediate floor, right?

andimann schrieb:

That’s an old myth and repeating it won’t make it better... For some years now, no HBCD is added so it’s no longer hazardous waste and can be disposed of normally by incineration. Which by the way is what mostly happens to the carefully sorted yellow bags (recycling bins). They are all burned with the residual waste....

HBCD is only half the story since even HBCD-free EPS is hard to separate from plaster. As far as I know, there is still work to do before EPS can simply be burned together with regular recycling waste.

andimann schrieb:

My recommendation: forget about the KfW 40+ nonsense and build the house with a sturdy, preferably heavy brick. Either sand-lime brick or Poroton hollow brick. Then ETICS in front, and that’s it.

I can’t agree with that conclusion. If you build with ETICS anyway, adding 2-4cm (1 inch) thicker insulation can bring you to the next better envelope quality level. That can be very rewarding.

What doesn’t work well is achieving super high insulation values with monolithic materials—they’re quite expensive and come with the other disadvantages mentioned here.

The future belongs to ETICS and timber frame construction when it comes to thermal insulation.

Baranej schrieb:

The sound insulation to the outside is rated at 51dB for the 24cm (9.4 inches) Poroton hollow brick by Wienerberger, which is great.

For example, it is even better than a 42.5cm (16.7 inches) T7 filled with mineral wool (48.x dB).

The problem is that the 24cm (9.4 inches) Poroton hollow brick with 51dB rating is neither useful for construction with ETICS (too thick unnecessarily, sand-lime brick can do the same with 17.5cm (6.9 inches)) nor suitable as a monolithic solution (insulation is too poor). So it doesn’t really help to present this brick here.

haydee schrieb:

ETICS made of Neopor/plastic only burns once exposed to air. For example, windows explode, plaster falls off, flames break through, and after about 20 minutes the facade is burning. If everything was installed properly.

If it burns that hard, the question is what is left of the house regardless of material.

If the EPS ETICS drips off your wall, you’re either already outside for 10 minutes or have other problems.

Yes, EPS is not perfect in that regard, but we have to be realistic about what that means in practice.

Tassimat schrieb:

Not always without problems. On renovated houses, sometimes you see those 5cm (2 inch) big dots. These are the washer anchors used for fixing. If you don’t repaint the entire facade every few years, it looks really bad. Nowadays anchors are recessed deeper, and then a cover made of insulation material is applied, or no anchors are used at all on new buildings if the manufacturer allows it.

Renovation is a different case, I believe.

In new builds, you generally don’t use anchors (for EPS). I haven’t seen that in dozens of new builds here.

Tassimat schrieb:

Correct, but with mineral wool you have to drill through to the wall. Anchors do not hold in the insulation itself. Anyone clumsy will rage when trying to screw something into the facade.

I initially wanted mineral wool. Aside from the higher price (I think about 10,000€), it was discouraged because of the anchors and resulting thermal bridges. Also, mineral wool can get wet and lose its insulation properties. EPS is sandable and therefore results in smoother plaster surfaces, especially with common thin-coat systems.

Granted, I can’t say how much of that is true. But the price alone is a massive deterrent (depending on the project, we’re talking about a 50% premium for the ETICS installation, just to put it in perspective).

parcus schrieb:

Ecologically and in terms of energy efficiency, timber frame construction is an alternative even for multi-family buildings.

Yes, although sometimes you don’t want to look too closely where the wood actually comes from.

@guckuck2

That should have been installed a long time ago,... 🙂

guckuck2 schrieb:

The problem is that the 24cm (9.5 inch) hollow clay brick with 51dB is neither practical for construction with ETICS (External Thermal Insulation Composite System) since it is unnecessarily thick—calcium silicate brick can achieve the same with 17.5cm (7 inch)—nor suitable as a monolithic solution (thermal insulation is too poor). Therefore, presenting this brick here is not helpful.

The inquiry was specifically about the 24cm (9.5 inch) hollow clay brick combined with ETICS (14cm (5.5 inch)) and its sound insulation values, as this combination was offered by the building contractor (see first post); it was not meant as a recommendation. Calcium silicate brick has apparently not yet been offered by the threadstarter’s building contractor. As a side note, even a 17.5cm (7 inch) hollow clay brick provides fairly decent sound insulation (~48dB).