ᐅ Materials for Exterior and Interior Walls (KfW 55 Standard)
Created on: 13 Aug 2021 14:16
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Baumeister86
Dear all,
After initial discussions with local general contractors and reviewing construction specifications, some questions arose regarding the wall materials (assembly).
We would like to build to the KfW 55 standard, as it doesn’t seem to deviate much from the usual practice. Additionally, we want good sound insulation (unfortunately, the air traffic from BER airport can still be heard in eastern Berlin, even though planes will not fly directly over us). Therefore, I am a bit overwhelmed by the many exterior wall options.
Monolithic construction seems advantageous to me, as masonry should last much longer than external thermal insulation composite systems (ETICS) and require less maintenance. Are there any reliable experiences with ETICS? Also, I’m a bit unsure about calcium silicate brick (best sound insulation, but I don’t want sand falling down every time I drill). How is the maintenance of facade render handled? I cannot recall my parents having that done in almost 30 years (house built in the late 1970s).
Porous concrete with a wall thickness of 36.5 cm (14 inches) should meet KfW requirements (U-value <0.2), while clay blocks require additional filling with perlite. However, from what I have researched, sound insulation of clay blocks is better than porous concrete, at least on paper. How does this compare in practice?
Lightweight expanded clay aggregate blocks were also offered to us (however, as a pre-assembled system wall). You would need a lot of ETICS on this to meet the KfW standard—how is the sound insulation in this case?
Most importantly, what are the costs of these options (calcium silicate brick + ETICS vs. porous concrete vs. insulated clay blocks) for, say, a city villa with a 10 x 10 m (33 x 33 ft) footprint? Most general contractors work only with one option or the other (and I have not yet found any insulated clay blocks).
To avoid noise transmission inside the house, regular clay block walls seem reasonable (12 cm or 24 cm [5 or 10 inches] if load-bearing). Calcium silicate bricks seem somewhat heavy (and the sand issue)?
Thank you very much for your opinions.
Stephan
P.S.: Are we really looking at 2100–2500 €/m² (195–230 $/ft²) for a “normal standard” house now in Brandenburg? Or did we consult the wrong general contractors?
After initial discussions with local general contractors and reviewing construction specifications, some questions arose regarding the wall materials (assembly).
We would like to build to the KfW 55 standard, as it doesn’t seem to deviate much from the usual practice. Additionally, we want good sound insulation (unfortunately, the air traffic from BER airport can still be heard in eastern Berlin, even though planes will not fly directly over us). Therefore, I am a bit overwhelmed by the many exterior wall options.
Monolithic construction seems advantageous to me, as masonry should last much longer than external thermal insulation composite systems (ETICS) and require less maintenance. Are there any reliable experiences with ETICS? Also, I’m a bit unsure about calcium silicate brick (best sound insulation, but I don’t want sand falling down every time I drill). How is the maintenance of facade render handled? I cannot recall my parents having that done in almost 30 years (house built in the late 1970s).
Porous concrete with a wall thickness of 36.5 cm (14 inches) should meet KfW requirements (U-value <0.2), while clay blocks require additional filling with perlite. However, from what I have researched, sound insulation of clay blocks is better than porous concrete, at least on paper. How does this compare in practice?
Lightweight expanded clay aggregate blocks were also offered to us (however, as a pre-assembled system wall). You would need a lot of ETICS on this to meet the KfW standard—how is the sound insulation in this case?
Most importantly, what are the costs of these options (calcium silicate brick + ETICS vs. porous concrete vs. insulated clay blocks) for, say, a city villa with a 10 x 10 m (33 x 33 ft) footprint? Most general contractors work only with one option or the other (and I have not yet found any insulated clay blocks).
To avoid noise transmission inside the house, regular clay block walls seem reasonable (12 cm or 24 cm [5 or 10 inches] if load-bearing). Calcium silicate bricks seem somewhat heavy (and the sand issue)?
Thank you very much for your opinions.
Stephan
P.S.: Are we really looking at 2100–2500 €/m² (195–230 $/ft²) for a “normal standard” house now in Brandenburg? Or did we consult the wrong general contractors?
We discovered the Liaplan block at a building expo.
We already had an idea of our floor plan and the specific features of the plot.
After visiting the factory in Brandenburg, we asked which companies build with this product.
We discussed the plans with three companies:
a family-run business worked really well,
a large company declined because it was too unusual,
and the third gave a defensive offer.
Now we live in the house and are confident we made the right choice.
Find a contractor you get along with and let them build with their preferred building material.
We already had an idea of our floor plan and the specific features of the plot.
After visiting the factory in Brandenburg, we asked which companies build with this product.
We discussed the plans with three companies:
a family-run business worked really well,
a large company declined because it was too unusual,
and the third gave a defensive offer.
Now we live in the house and are confident we made the right choice.
Find a contractor you get along with and let them build with their preferred building material.
Berlinho schrieb:
The remaining question is number 2 – Is there a "winner" here?
What about durability, in terms of "leaving something behind for the grandchildren" (if there will ever be any)?
Or should the deliberate omission of the answer be understood as follows:
Durability, insulation, and soundproofing are so similar for both materials that the choice of stone/brick should not determine the contractor you select, meaning you shouldn’t limit yourself when choosing a builder just because one prefers to build with sand-lime brick instead of clay brick or vice versa? I deliberately skipped that question – right here, just about 40 km (25 miles) away diagonally, a variety of houses have literally sunk or been washed away before they could be inherited – so you don’t need to worry about eight hundred years with one stone versus nine hundred with the other in a flood-free environment. Timber framing often lasts twelve hundred years.
You won’t be able to build with sand-lime brick without exterior insulation (ETICS/WDVS) due to energy regulations, so at this point, we’re back to the fundamental question of personal preference. Within the monolithic construction spectrum, the options are manageable. Only with unfilled porous bricks do I tend to disagree the least with the "preachers" against them 🙂
Berlinho schrieb:
I’m already taking away not to be too rigid, especially if you don’t really know much yourself! You can score unforgettable own goals by pushing a builder to work with an unfamiliar masonry material. Likewise, I would never try to convert a builder away from or towards exterior insulation systems. The same applies to interior walls, whether masonry or lightweight construction.
Ceterum censeo (furthermore I consider), castle wall thicknesses are nonsense. Anyone who sees wall construction as a simple rule of three, assuming everything works monolithically, and then demands ninety-three centimeters (about 37 inches) thick concrete walls based on the oracle-like prophecy of their U-value calculator, in my opinion, is seriously misguided.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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Baumeister8615 Aug 2021 22:07motorradsilke schrieb:
We are currently building in Brandenburg as well, and that estimate is pretty accurate. After the initial selection of materials and the first moderate price increase, we will end up at around 2200 €/sqm (roughly 205 sq ft), excluding additional construction costs and landscaping, but with KfW55 standard. @motorradsilke Thanks, then the first offers weren’t too far off.
Off-topic here: I read in another thread that you also had to demolish something before building? Could you roughly tell me what you demolished and what the costs were? We need to remove 64 sqm (roughly 688 sq ft) spread over 1.5 floors plus a partial basement...
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motorradsilke16 Aug 2021 06:20Baumeister86 schrieb:
@motorradsilke Thanks, then the initial quotes weren’t that far off after all.
Off-topic here: I read in another thread that you also had to demolish before building? Could you roughly tell me what you had to tear down and how much it cost? We need to remove 64 sqm (688 sq ft) spread over 1.5 floors plus a partial basement. We had our old house demolished. It was about 80 sqm (860 sq ft) plus a small basement of around 8 sqm (86 sq ft). However, we stripped it out ourselves first because the doors, windows, and metal roof covering were still useful for my sons’ sheds and animal shelters. For demolishing the remaining masonry and backfilling, we paid around 20,000 euros.
We could have done it cheaper (14,000), but we wanted the demolition done by the same contractor who is building the new house. On one hand, because we needed seamless coordination (we have to finish as quickly as possible since we’re currently living in a container on the property). On the other hand, so that in case of any problems (cracks or similar in the masonry) it wouldn’t be possible to shift responsibility from one party to another.
motorradsilke schrieb:
We are currently building in Brandenburg as well, and that estimate seems accurate. After finalizing selections and the first moderate price increase, we expect to reach around 2200 €/m² (204 sq ft), excluding additional construction costs and landscaping, but meeting KfW55 energy efficiency standards. That would be a standard specification, right? Either without many extras or a typical development like Town & Country or Heinz von Heiden? With a gas condensing boiler, no photovoltaic system, no controlled residential ventilation, as well as a fireplace and other extras, you would be looking at about 2200 to 2300 €/m² (204 to 214 sq ft). If it turns out to be a city villa rather than a bungalow, the price would match yours.
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motorradsilke16 Aug 2021 07:44Acof1978 schrieb:
But that would be a standard specification, right? Either without many extras or a typical build from Town & Country or Heinz von Heiden? With a gas condensing boiler, no photovoltaic system, no mechanical ventilation with heat recovery, as well as a chimney and other extras, the cost would be around €2,200–2,300 per square meter (approximately $205–215 per square foot). If it were to be an urban villa instead of a bungalow, it would match your price. With a small local builder. Bungalow, heat pump, chimney for the fireplace, electric roller shutters, no mechanical ventilation with heat recovery, no photovoltaic system, no KNX. We will install the fireplace ourselves.