ᐅ Cost Difference Between External Thermal Insulation Composite Systems (ETICS) and Energy-Efficient Bricks, Future Expenses, Single-Family Home

Hello everyone,

we are planning to build a single-family house. We have already spoken with several construction companies, but have heard many different opinions.

We want: KfW 70 standard with ETICS T8, 36.5 cm (14 inches) thick (lambda 0.08, overall U-value approx. 0.21 W/m²K) without external thermal insulation composite system (ETICS) due to concerns about algae growth, etc. One company told us that the cost is about the same whether you choose ETICS or ETICS-free. Another company says that using ETICS would result in additional costs of around 8,000 – 10,000 EUR, based on ETICS with 12 cm (5 inches) EPS insulation and 24.5 cm (10 inches) hollow bricks, with an overall U-value of approx. 0.22 W/m²K. The house has a footprint of about 11.4 x 8.7 m (37 x 29 feet) and a knee wall height of about 75 cm (30 inches).

As laypersons, we think that ETICS is much more complex since masonry work is necessary either way, and then ETICS has to be applied on top. ETICS costs money and also involves more labor. Using ETICS-free hollow bricks costs more than standard 24.5 cm solid bricks, which is clear.

Is it really possible that additional costs of this magnitude can occur? What are your experiences?

If you need more information, please let us know!!!

Thanks for your help!!!

Best regards,
Otti

Mate, you want to insulate the facade, not the floor plan, right? Here, you’re only providing the area of the knee wall, and then doubling it. No one can really help you with that!

Hello, we received information from a general contractor (GC) who usually builds with aerated concrete blocks (Ytong 36.5 cm (14.4 inches)) that using T8 bricks 36.5 cm (14.4 inches) would lead to additional costs of about 8,000 to 12,000 EUR for a two-story house of approximately 180-200 m² (1,938-2,153 sq ft). Interestingly, this GC’s show home is built with T8 bricks rather than the aerated concrete blocks they normally use in their houses. Another very large GC, who typically builds with 17.5 cm (6.9 inches) hollow bricks (unfilled) plus 16 cm (6.3 inches) external thermal insulation composite system (ETICS / external wall insulation), had T8 and T7 bricks on display in their show home but could not provide any price information. “Additional cost for sure,” was their comment. Generally, if extra demands are made, GCs tend to charge hefty surcharges, and so far, I haven’t found a GC who routinely builds with T8 bricks (any recommendations for the Berlin/Brandenburg area are welcome via private message). Especially when you want something specific like a different building envelope (which we do), working with GCs becomes difficult. On the other hand, any potential cost advantages with more individual planning and subcontracting through an architect vanish when you consider their fees. Ideally, it would be best to find a GC who already standardly builds with T8 bricks or at least has significant experience working with them.

I have contacted two local house building companies in the region (B, BB) to inquire about the expected additional costs:

A townhouse with approximately 240 m² (2583 ft²) of wall surface area or 88 m³ (3105 ft³) with 36.5 cm (14.4 inches) bricks. Windows are not included, but I assume there will be waste and special bricks for roller shutters, etc., which cost extra.

So far, I have received quotes from three suppliers for the following exterior walls:

a) insulated Thermopor bricks with a lambda value of 0.09 and mineral render
b) non-insulated Poroton Plan T10 with reinforcing mesh and mineral render
c) aerated concrete according to structural requirement 17.5 cm (6.9 inches) with ETICS 16 cm (6.3 inches) and synthetic resin render

a) did not provide a detailed wall build-up separately, but the final price is correct; however, I 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 only built T8 once or twice. Result: an additional cost of 7,500 to 9,000 euros. I am still in discussions, as the difference compared to the calculated extra cost is “only” about 3,500 to 4,000 euros.

c) ruled itself out due to intimidating additional costs: depending on the brick type, 13,000 to 14,000 euros more. Apparently, the preferred shell builders cannot do this, or the company makes good profit and does not want to accommodate special requests...

Insulated bricks, regardless of the manufacturer, are very expensive. Expect at least 60 to 65 euros per m² (5.60 to 6.00 USD per sq ft) of personal capital just for the t9/T8 brick. Non-insulated options, e.g., Poroton Plan T10, are available for about 44 euros per m² (4 USD per sq ft), while aerated concrete is likely cheaper.

I assume this financially never pays off, however:

Advantages of bricks compared to ETICS: slower facade soiling, less prone to algae and fungi (purely an aesthetic issue, but it bothers me)
Advantage of insulated bricks compared to non-insulated: thicker webs = less prone to cracking + easier to fix loads.

The question is:

How much more expensive is ETICS compared to a proper mineral render, possibly reinforced with mesh? For render, I estimate at least 30 euros per m² (2.80 USD per sq ft). Prices for ETICS vary widely “on the internet” here: from around 50 euros up to 100 euros per m² (4.60 to 9.30 USD per sq ft). Everyone can assess for their own project what costs the builder incurs and what we have to pay.

Everyone, please stop with these fairy tales.
An algae problem is caused by low surface temperatures.
This applies to any highly insulated exterior wall, whether it is constructed with an external thermal insulation composite system (ETICS) or an insulated masonry unit.

Lately, I have read some unbelievable claims about significantly higher costs for so-called "insulated masonry units."
These can only be defensive offers. Possibly, the standard brick manufacturer of the shell builder does not carry the desired brick, so it must be sourced elsewhere, often without much discount.

- Kalksandstein

@karliseppel That’s not entirely correct. According to studies by the Fraunhofer Institute, ETICS (External Thermal Insulation Composite Systems) are more prone to algae growth than monolithic exterior walls. This is one reason why I personally plan in that direction, but unfortunately, there is a lack of companies in this region offering this, which is naturally a disadvantage. Since I don’t want to post links here anymore, simply search on Google for "Contribution to the 3rd Dahlberg Colloquium Microorganisms and Building Maintenance." In that study by the Fraunhofer Institute, it is well explained why ETICS are more susceptible to algae. When I walk through the streets here, it’s also easy to see which buildings have monolithic walls and which ones have thick ETICS applied (the latter are the ones with the green walls). But you are right that unjustified higher prices can also result from contractors wanting to build with nothing but the cheapest or most profitable materials for them.