Price difference WDVS / energy-saving bricks, later costs, single-family house

Hello everyone,

we plan to build a single-family house. We have already spoken with various construction companies but have heard many different opinions.

We want: Kfw70 with ESZ T8 at a thickness of 36.5 cm (Lambda 0.08, overall U-value approx. 0.21 W/m²K) without WDVS (algae growth, etc.). Now we received information from one company that it makes no difference in price whether you use ESZ or WDVS. The other company says that ESZ results in additional costs of about 8,000 – 10,000 EUR compared to WDVS (EPS 12cm and perforated brick 24.5cm, overall U-value approx. 0.22 W/m²K). The house has a footprint of about 11.4 x 8.7 m and a knee wall height of about 75 cm.

As laymen, we think that the effort for WDVS is significantly greater because masonry has to be done anyway and in addition WDVS must be applied. The WDVS costs money and the labor effort is also higher. The ESZ costs more than a normal 24.5 cm brick, that is clear.

Can it really be that additional costs of the mentioned amount can arise? What are your experiences?

If more information is needed, please let us know!!!

Thanks for your help!!!

Regards Otti

Colleague, you want to insulate the facade and not the floor plan, right? Here you are just delivering the area of the knee wall and that times 2. No one can really help you like this!

Hello, we received information from a general contractor (GU) who normally builds with aerated concrete (Ytong 36.5 cm) that using T8 36.5 leads to additional costs of 8,000-12,000 EUR for a 2-story house of about 180-200 m². Interestingly, this GU's show house is built with T8 and not with the aerated concrete they normally use in their houses. Another very large GU who normally builds 17.5 cm perforated bricks (unfilled) + 16 cm ETICS has T8 and T7 bricks at their show house but could not provide any price information. "Additional costs but definitely." Usually, it will be the case that if you want special requests, GUs charge hefty surcharges, and I have not yet found a GU who regularly builds with T8 (tips for the Berlin/Brandenburg area are welcome via PM to me). Especially when it comes to fundamental things like the building envelope and you want a special feature (which we do, by the way), it is difficult with GUs. On the other hand, you do not gain anything from possible cost advantages with more individual planning and contracting with an architect when you look at their fees. Ideally, it would be to find a GU who already builds with T8 by default or at least has a lot of experience building with it.

I have inquired myself with two house construction companies in the region (B, BB) about the additional costs to be expected:

Townhouse with approx. 240 m² wall surface requirement or 88 m3 with 36.5 cm bricks. Windows are not included, but I assume there will be breakage and special bricks for roller shutters, etc., which cost extra.

So far, I have offers from three providers for the following exterior walls:

a) filled Thermopor bricks with lambda 0.09 and mineral plaster
b) unfilled Poroton Plan T10, reinforcing mesh and mineral plaster
c) aerated concrete according to static requirements 17.5 cm and WDVS 16 cm and synthetic resin plaster

a) did not specify the wall construction separately, but the final price is correct; I just do not know the difference between Thermopor, e.g., from Röben, and Poroton, e.g., from Schlagmann or Wienerberger.

b) focused on the Plan T10 and built T8 only once or twice. Result: 7.5 - 9 THOUSAND EUR extra cost. I am still in talks because the difference to the calculated additional cost is "only" about 3.5-4 THOUSAND EUR.

c) eliminated itself due to discouraging additional costs: depending on the brick, 13 to 14 THOUSAND EUR more. Apparently, the preferred shell builders cannot do it or the company earns well and does not want any special favors...

Filled bricks, regardless of the manufacturer, are very expensive. Expect at least 60-65 euros per m² equity capital just for the t9/T8 brick. Unfilled, e.g., the Poroton Plan T10 is already available for about 44 euros per m², aerated concrete is probably even cheaper.

I assume that financially it never pays off, however:

Advantages of bricks compared to WDVS: Slower facade soiling, less prone to algae and fungi (purely an optical problem, but it bothers me)
Advantage of filled bricks over unfilled: thicker web widths = less prone to cracking + easier to attach loads.

The question is:

How much more expensive is a WDVS compared to a proper mineral plaster, which might still be reinforced with mesh? For plaster, I calculate at least 30 euros per m². The prices for 1 m² WDVS vary quite a bit here "on the internet": from about 50 euros up to 100 euros per m². Everyone can estimate for their own project what costs the construction company will incur and what we are supposed to pay.

Guys, please stop with this fairy tale.
An algae problem is a problem of a low surface temperature.
And this applies to every highly insulated exterior wall! Regardless of whether it was made with an ETICS or an insulating brick.

I have recently read adventurous things about considerable surcharges for so-called "insulating bricks."
This can only be defensive offers. Possibly the standard brick manufacturer of the shell builder does not carry the desired brick, and it must be sourced elsewhere more or less without a discount.

-ks

@karliseppel That is not entirely correct. According to studies from Fraunhofer, ETICS are more susceptible to algae growth than monolithic exterior facades. One of the reasons why I personally plan in this direction, but unfortunately there is a lack of companies in this region offering this, which of course is also a disadvantage. Since I no longer want to post links here: simply search on Google for "Beitrag zum 3. Dahlberg-Kolloquium Mikroorganismen und Bauwerksinstandsetzung". There, a study from the Fraunhofer Institute explains quite well why ETICS are more susceptible to algae. When I walk through the streets here, it is also immediately obvious from the buildings which ones are monolithic and which ones have thick ETICS (namely those with the green walls). But you are right that unjustified higher prices can also simply arise from the fact that construction companies want to build with nothing other than the cheapest/most profitable building materials for them.