ᐅ Basement and Wall Construction in New Builds – Experiences
Created on: 14 Feb 2012 12:02
B
Bauender1977B
Bauender197714 Feb 2012 12:02Hello everyone,
I have been reading this forum for a long time since we decided to build a single-family house with an architect. During our initial research phase, many questions arose that resolved themselves through extensive reading. However, there are still some questions left open. I would like to post them here and get your opinions/comments. If this is posted in the wrong forum, please feel free to move it.
- Basement topic:
Since the groundwater on our plot begins at a depth of about 3 meters (10 feet), and considering that the open-pit mine in our region (VIE) had to end groundwater lowering measures sometime around 2016, we need to build a basement with a "white tank" (watertight concrete). According to a quote, a roughly 100 m² (1,076 sq ft) insulated (KFW 55) waterproof prefabricated basement costs about €50,000 plus excavation costs around €20,000. If I want to create several additional rooms (including windows, insulation, and underfloor heating) on the ground floor and/or upper floor, I roughly calculate that I could get about 40 m² (430 sq ft) for the same price, assuming a cost of about €1,400 per m². Could that be correct, or have I missed something in my calculation?
Building plot: 15 m wide x 24 m long (49 ft x 79 ft)
Building envelope: 9 m wide x 15 m long (30 ft x 49 ft)
- Wall construction topic:
As I have read here and elsewhere, there is no perfect solution for wall construction. It depends on many factors. Since we will be building near a railway line (up to 60 dB during the day), we have decided on a calcium silicate block wall construction with a central mechanical ventilation with heat recovery system. Since we want to heat relatively little, we do not want a thin standard wall but rather a bit more insulation. How much more expensive is it to install 240 mm (9.5 inches) of mineral wool insulation instead of 160 mm (6.3 inches) on the house?
Wall construction:
1.5 cm (0.6 inches) gypsum plaster
17.5 or 24 cm (7 or 9.5 inches) calcium silicate blocks (bulk density class 1.2)
24 cm (9.5 inches) mineral wool insulation, thermal conductivity 0.032 W/(m·K)
1.5 cm (0.6 inches) cement plaster
Thank you very much in advance for your answers.
Best regards,
Sebastian
I have been reading this forum for a long time since we decided to build a single-family house with an architect. During our initial research phase, many questions arose that resolved themselves through extensive reading. However, there are still some questions left open. I would like to post them here and get your opinions/comments. If this is posted in the wrong forum, please feel free to move it.
- Basement topic:
Since the groundwater on our plot begins at a depth of about 3 meters (10 feet), and considering that the open-pit mine in our region (VIE) had to end groundwater lowering measures sometime around 2016, we need to build a basement with a "white tank" (watertight concrete). According to a quote, a roughly 100 m² (1,076 sq ft) insulated (KFW 55) waterproof prefabricated basement costs about €50,000 plus excavation costs around €20,000. If I want to create several additional rooms (including windows, insulation, and underfloor heating) on the ground floor and/or upper floor, I roughly calculate that I could get about 40 m² (430 sq ft) for the same price, assuming a cost of about €1,400 per m². Could that be correct, or have I missed something in my calculation?
Building plot: 15 m wide x 24 m long (49 ft x 79 ft)
Building envelope: 9 m wide x 15 m long (30 ft x 49 ft)
- Wall construction topic:
As I have read here and elsewhere, there is no perfect solution for wall construction. It depends on many factors. Since we will be building near a railway line (up to 60 dB during the day), we have decided on a calcium silicate block wall construction with a central mechanical ventilation with heat recovery system. Since we want to heat relatively little, we do not want a thin standard wall but rather a bit more insulation. How much more expensive is it to install 240 mm (9.5 inches) of mineral wool insulation instead of 160 mm (6.3 inches) on the house?
Wall construction:
1.5 cm (0.6 inches) gypsum plaster
17.5 or 24 cm (7 or 9.5 inches) calcium silicate blocks (bulk density class 1.2)
24 cm (9.5 inches) mineral wool insulation, thermal conductivity 0.032 W/(m·K)
1.5 cm (0.6 inches) cement plaster
Thank you very much in advance for your answers.
Best regards,
Sebastian
B
Bauexperte14 Feb 2012 12:24Hello Sebastian,
No, that roughly matches the cost of the basement; a basement is always a very expensive storage area, especially since additional waterproofing measures are required—WU concrete alone is not sufficient. Why does your architect estimate excavation costs at €20,000?
Given this plot size and considering the soil conditions and open-cast mining, why do you want to build a basement at all? Are the zoning plan (building permit/planning permission) requirements so restrictive that you can only build a single story without knee walls? If not, I would discuss alternative solutions with your architect that would likely be significantly more cost-effective.
I can’t answer that without knowing the building’s dimensions. What does your architect or structural engineer say?
You should also consider that the more insulation you add, the smaller the interior spaces become—since you must stay within the building plot dimensions. It always sounds minor when people say “just 8 cm more.” Calculate it continuously around the perimeter on each floor.
Hmm... I’m not sure if I would recommend calcium silicate blocks; railway proximity aside. The sound insulation is excellent, but you compromise on thermal insulation—not to mention heat storage capacity.
Kind regards
Bauender1977 schrieb:
According to a quote, a waterproof prefabricated basement of about 100 m² insulated to KfW 55 standard costs around €50,000 plus excavation worth about €20,000. If I want to create several additional rooms (including windows, insulation, and underfloor heating) on the ground floor and/or upper floor, I get roughly 40 m² for this price (at about €1400 per m²). Could that be correct, or did I miss something in my calculation?
No, that roughly matches the cost of the basement; a basement is always a very expensive storage area, especially since additional waterproofing measures are required—WU concrete alone is not sufficient. Why does your architect estimate excavation costs at €20,000?
Bauender1977 schrieb:
Building plot dimensions: 10 m wide x 16 m long
Given this plot size and considering the soil conditions and open-cast mining, why do you want to build a basement at all? Are the zoning plan (building permit/planning permission) requirements so restrictive that you can only build a single story without knee walls? If not, I would discuss alternative solutions with your architect that would likely be significantly more cost-effective.
Bauender1977 schrieb:
Because we will be building near a railway line with noise levels up to 60 dB during the day, we opted for a load-bearing wall structure made of calcium silicate blocks with a central mechanical ventilation system with heat recovery. Since we don’t want to heat much, we prefer more insulation instead of a thin standard wall. How much more expensive is it to apply 240 mm mineral wool insulation instead of 160 mm to the house?
I can’t answer that without knowing the building’s dimensions. What does your architect or structural engineer say?
You should also consider that the more insulation you add, the smaller the interior spaces become—since you must stay within the building plot dimensions. It always sounds minor when people say “just 8 cm more.” Calculate it continuously around the perimeter on each floor.
Hmm... I’m not sure if I would recommend calcium silicate blocks; railway proximity aside. The sound insulation is excellent, but you compromise on thermal insulation—not to mention heat storage capacity.
Kind regards
B
Bauender197714 Feb 2012 13:59Hello building expert,
thank you for your reply. I didn’t expect a response that quickly.
To clarify my question, we are currently in the initial discussions with the architect, and we just wanted to roughly estimate how many square meters of basement space you can get if you build above ground.
We don’t want to use the basement just as a “large storage area” but also as a fully functional office and hobby/media room. For this reason, it should have a ceiling height of 2.5 meters (the increase is included in the quote for about 2,500 euros) and feature underfloor heating. Of course, the basement will also house building services (central controlled ventilation system, buffer tank, gas boiler with pre-installed connections/openings for a brine heat pump, distribution, possibly building automation), storage rooms, and laundry facilities. A rough calculation of the basement rooms gives us around 50 m² (540 sq ft).
This price (50,000 euros) already includes insulation and construction as a “white tank” (watertight concrete structure).
The open-pit lignite mine is quite a distance from us. However, they are significantly lowering the groundwater level by pumping out groundwater in our area. According to the zoning plan, the current groundwater level is about 3 meters (10 feet) below ground level.
I don’t know if the regulations are very strict. I took the following data from the zoning plan:
Eaves height: 4.5 meters (15 feet)
Gable roof pitch: 38°-42°
Two storeys
Site coverage ratio: 0.4
The architect immediately said he would build without a basement. We simply wanted to estimate what would be more cost-effective and what advantages it would bring. As a building novice, it seems like above-ground costs are higher than underground ones. But since you also recommend this, there must be some truth to it.
I understand that by not excavating you have fewer issues with groundwater, but you know basements from the past, from your parents’ house...
Of course, we see that the living space will get smaller, but it’s only about estimating when extra insulation will pay off. If 160 mm (6.3 inches) of insulation costs X €/m² and 240 mm (9.5 inches) costs twice as much, it’s not worthwhile to build better than KfW 70 standard right now.
The specified decibel value is from the zoning plan. When we spent a night near the railway line, we barely heard the trains when it was quiet. Also, we plan to install a controlled ventilation system in the house, so we will hear even less.
Best regards
Sebastian
thank you for your reply. I didn’t expect a response that quickly.
To clarify my question, we are currently in the initial discussions with the architect, and we just wanted to roughly estimate how many square meters of basement space you can get if you build above ground.
Bauexpert schrieb:
No, that’s about right for the basement; a basement is always a very expensive storage area, with additional waterproofing measures required, especially since WU (waterproof) concrete alone is not enough. Why does your architect estimate excavation costs at 20,000 euros?
We don’t want to use the basement just as a “large storage area” but also as a fully functional office and hobby/media room. For this reason, it should have a ceiling height of 2.5 meters (the increase is included in the quote for about 2,500 euros) and feature underfloor heating. Of course, the basement will also house building services (central controlled ventilation system, buffer tank, gas boiler with pre-installed connections/openings for a brine heat pump, distribution, possibly building automation), storage rooms, and laundry facilities. A rough calculation of the basement rooms gives us around 50 m² (540 sq ft).
This price (50,000 euros) already includes insulation and construction as a “white tank” (watertight concrete structure).
Bauexpert schrieb:
Why do you want to build a basement in this building area and considering the soil conditions and open-pit mining? Are the zoning plan restrictions so tight that you are only allowed to build a single storey without knee walls? If not, I would recommend discussing another solution with the architect, which could be significantly more cost-effective in the long run.
The open-pit lignite mine is quite a distance from us. However, they are significantly lowering the groundwater level by pumping out groundwater in our area. According to the zoning plan, the current groundwater level is about 3 meters (10 feet) below ground level.
I don’t know if the regulations are very strict. I took the following data from the zoning plan:
Eaves height: 4.5 meters (15 feet)
Gable roof pitch: 38°-42°
Two storeys
Site coverage ratio: 0.4
The architect immediately said he would build without a basement. We simply wanted to estimate what would be more cost-effective and what advantages it would bring. As a building novice, it seems like above-ground costs are higher than underground ones. But since you also recommend this, there must be some truth to it.
I understand that by not excavating you have fewer issues with groundwater, but you know basements from the past, from your parents’ house...
Bauexpert schrieb:
I can’t answer that without knowing the volume of the building. What do your architect or the structural engineer say?
Bauexpert schrieb:
You must also consider that the more insulation you add, the smaller the interior rooms become – as you have to stay within the building limits. People often say “it’s just 8 cm (3 inches) more” but calculate that all around per floor.
Hmm... I’m not sure I would recommend sand-lime bricks; railway line or not. The sound insulation is excellent, but you pay for poor thermal insulation and there’s no benefit in terms of thermal mass.
Of course, we see that the living space will get smaller, but it’s only about estimating when extra insulation will pay off. If 160 mm (6.3 inches) of insulation costs X €/m² and 240 mm (9.5 inches) costs twice as much, it’s not worthwhile to build better than KfW 70 standard right now.
The specified decibel value is from the zoning plan. When we spent a night near the railway line, we barely heard the trains when it was quiet. Also, we plan to install a controlled ventilation system in the house, so we will hear even less.
Best regards
Sebastian
B
Bauexperte14 Feb 2012 20:30Hello Sebastian,
Then I have to—regretfully—correct my initial response. For a residential basement—regardless of the building services/technology—built as a "white tank" (this term is actually incorrect but unfortunately widely used; I believe I understand what you mean) 50,000 Euro will not be sufficient. Even if I assume it is only a waterproof concrete basement (WU concrete), it won’t be enough.
That still does not explain the 20,000 Euro budgeted for earthworks.
If two storeys are allowed, 4.5 meters (14 feet 9 inches) eaves height makes no sense, as this height is typically for a one-storey building with a corresponding knee wall. I assume the zoning permits up to two storeys and you just forgot to mention the ridge height here; it should be somewhere between 9.00 and 10.00 meters (30 to 33 feet); anything else would not make sense.
Also from Viersen or the surrounding area?
Then save your money on additional soundproofing—regarding the extra cost for KfW 55 certification, I would reconsider as well (the monthly energy savings compared to KfW 70 don’t really amortize when looking at the investment cost); after all, it is a sum in the approximate range of 25,000 Euro—and consider a monolithic 36.5 cm (14.4 inch) wall construction. That way, the basement won’t hurt the budget quite as much.
Best regards
Bauender1977 schrieb:
We want to use this basement not only as a "large storage area" but also additionally as a fully functional office and hobby/media room. For this reason, it should have a ceiling height of 2.5 meters (8 feet 2 inches) (the increase is included in the offer for approx. 2,500 Euro) and feature underfloor heating. Of course, the basement will include building services (central controlled residential ventilation, buffer tank, gas boiler with prepared connections/openings for a brine heat pump, distribution, possibly home automation), storage room, and laundry room. We roughly calculated the basement rooms at 50 m² (540 ft²). The price (50,000 Euro) already includes insulation and construction as a waterproof concrete structure ("white tank").
Then I have to—regretfully—correct my initial response. For a residential basement—regardless of the building services/technology—built as a "white tank" (this term is actually incorrect but unfortunately widely used; I believe I understand what you mean) 50,000 Euro will not be sufficient. Even if I assume it is only a waterproof concrete basement (WU concrete), it won’t be enough.
Bauender1977 schrieb:
The lignite open-pit mine is quite a distance from us. However, they lower the groundwater level significantly by pumping out groundwater. According to the development plan, the groundwater distance from the surface is currently about 3 meters (10 feet) below ground level.
That still does not explain the 20,000 Euro budgeted for earthworks.
Bauender1977 schrieb:
I don’t know whether the requirements are too strict. I took the following data from the development plan: eaves height: 4.5 meters (14 feet 9 inches), pitched roof 38°–42°, two storeys, site coverage ratio: 0.4
If two storeys are allowed, 4.5 meters (14 feet 9 inches) eaves height makes no sense, as this height is typically for a one-storey building with a corresponding knee wall. I assume the zoning permits up to two storeys and you just forgot to mention the ridge height here; it should be somewhere between 9.00 and 10.00 meters (30 to 33 feet); anything else would not make sense.
Bauender1977 schrieb:
The architect .....
Also from Viersen or the surrounding area?
Bauender1977 schrieb:
This specified dB value is from the development plan. When we spent a night near the railway line, we could barely hear the trains when we were quiet. Also, we will install a controlled residential ventilation system in the house, so we will hear even less.
Then save your money on additional soundproofing—regarding the extra cost for KfW 55 certification, I would reconsider as well (the monthly energy savings compared to KfW 70 don’t really amortize when looking at the investment cost); after all, it is a sum in the approximate range of 25,000 Euro—and consider a monolithic 36.5 cm (14.4 inch) wall construction. That way, the basement won’t hurt the budget quite as much.
Best regards
B
Bauender197715 Feb 2012 12:16Hello Construction Expert,
thank you for answering our questions. In this thread, we have made more progress than in conversations with sellers of solid (masonry) houses. Some even got irritated when technical questions and questions about the wall construction were asked. Sad, but true. And this is how they want to sell a house... not with us! There are many sayings about “being friendly” for a reason.
What I meant was indeed a prefabricated waterproof concrete basement. This additionally has insulation between the two outer walls to meet KfW energy standards in the basement. However, I must also mention that the cost of EUR 50,000 (about USD 54,000) refers only to the bare basement without any fittings. Additional costs for utility lines, wallpaper, flooring, and heating are added on top. The excavation costs were just my rough estimate as a layperson. In the meantime, I am wiser and now see the costs rather at EUR 6,000 to 8,000 (about USD 6,500 to 8,600).
To be honest, you are confusing me now. Everyone we talked to said it is a 1.5-story house (whatever that means).
In the development plan it says the following:
WA = General residential area
0.4 = Floor area ratio
EH 4.5 m (14 ft 9 in) = Eave height 4.5 meters
SD 38-42° = Gable roof 38-42 degrees
I can gladly send you the link to the development plan via private message.
Surrounding area, but easily accessible. Why do you ask?
We already considered that it might be economically better to build only to KfW 70 standards. But as non-experts we couldn’t prove it. Because when you hear passive house builders talk about monthly heating costs of 50 euros, that sounds very good. But if I then take additional costs of EUR 25,000 (about USD 27,000) as a basis, the money – without maintenance costs and interest – is only paid back in around 30 years at best, which is not so great anymore. -->So our suspicion has been confirmed that it currently does not pay off to build better than KfW 70. And that only for the low-interest loan.
The only “luxury” we want to afford here is underfloor heating and a centralized controlled ventilation system with heat and moisture recovery. But you have to be a little uneconomical sometimes and support the German industry.
What do you mean by saying that with a monolithic wall the basement won’t hurt as much? Do you mean either to omit it or to include the costs within the budget?
What material should this monolithic wall ideally be made of?
T8/T9 or even T7?
Aerated concrete (Ytong Planblock W PP)?
Regards
Sebastian
thank you for answering our questions. In this thread, we have made more progress than in conversations with sellers of solid (masonry) houses. Some even got irritated when technical questions and questions about the wall construction were asked. Sad, but true. And this is how they want to sell a house... not with us! There are many sayings about “being friendly” for a reason.
Bauexperte schrieb:
Then I have to - as sorry as I am - correct my initial reply. For a basement - regardless of the house connections/technology - built as a “white tank” (this term is actually incorrect but unfortunately has become common; I think I know what you mean) EUR 50,000 (about USD 54,000) will not be enough. Even if I assume it is just a waterproof concrete basement without additional insulation, no.
Bauexperte schrieb:
That still does not explain the EUR 20,000 (about USD 21,600) set for excavation work.
What I meant was indeed a prefabricated waterproof concrete basement. This additionally has insulation between the two outer walls to meet KfW energy standards in the basement. However, I must also mention that the cost of EUR 50,000 (about USD 54,000) refers only to the bare basement without any fittings. Additional costs for utility lines, wallpaper, flooring, and heating are added on top. The excavation costs were just my rough estimate as a layperson. In the meantime, I am wiser and now see the costs rather at EUR 6,000 to 8,000 (about USD 6,500 to 8,600).
Bauexperte schrieb:
If two-story construction is allowed, then a 4.50 m (14 ft 9 in) eave height makes no sense, as this is actually the height for a one-story house with a corresponding knee wall. I assume that up to two stories are allowed in the building zone and that you simply forgot to add the ridge height here; it should be somewhere between 9.00 and 10.00 m (29 ft 6 in to 32 ft 10 in); anything else would not make sense.
To be honest, you are confusing me now. Everyone we talked to said it is a 1.5-story house (whatever that means).
In the development plan it says the following:
WA = General residential area
0.4 = Floor area ratio
EH 4.5 m (14 ft 9 in) = Eave height 4.5 meters
SD 38-42° = Gable roof 38-42 degrees
I can gladly send you the link to the development plan via private message.
Bauexperte schrieb:
Also from Viersen or the surrounding area?
Surrounding area, but easily accessible. Why do you ask?
Bauexperte schrieb:
Then save your money on additional insulation – I would reconsider the extra cost for KfW 55 as well (the monthly energy savings compared to KfW 70 do not really pay off when you consider the investment); it is after all an amount in the range of EUR 25,000 (about USD 27,000) – and consider a monolithic wall construction with 36.5 cm (14 inches) wall thickness. Then the basement won’t hurt as much anymore.
We already considered that it might be economically better to build only to KfW 70 standards. But as non-experts we couldn’t prove it. Because when you hear passive house builders talk about monthly heating costs of 50 euros, that sounds very good. But if I then take additional costs of EUR 25,000 (about USD 27,000) as a basis, the money – without maintenance costs and interest – is only paid back in around 30 years at best, which is not so great anymore. -->So our suspicion has been confirmed that it currently does not pay off to build better than KfW 70. And that only for the low-interest loan.
The only “luxury” we want to afford here is underfloor heating and a centralized controlled ventilation system with heat and moisture recovery. But you have to be a little uneconomical sometimes and support the German industry.
What do you mean by saying that with a monolithic wall the basement won’t hurt as much? Do you mean either to omit it or to include the costs within the budget?
What material should this monolithic wall ideally be made of?
T8/T9 or even T7?
Aerated concrete (Ytong Planblock W PP)?
Regards
Sebastian
B
Bauexperte15 Feb 2012 18:14Hello Stefan,
No need to thank me; I’m happy to do it, especially since it makes it harder for the "sellers/providers" you described to push their “trade” onto the builders; the same applies, of course, to the flip side of the coin.
That makes sense to me.
This estimate is realistic if your soil falls into classes 3-5; if your soil has other classifications (e.g., clay or similar), you should expect additional foundation costs up to around 8,000 euros.
*Chuckles* – 1.5 stories is colloquial; technically, there are only 1-, 2-, or 3- (or more) story buildings. In our work, we always refer to full floors. Regarding the data you provided:
"The development plan states: WA = general residential area, 0.4 = floor area ratio, TH 4.5 m = eaves height 4.5 meters, and SD 38–42 degrees = pitched roof 38–42°"
this clearly refers to 1 full floor (ground floor) plus knee wall (dormer wall) up to an eaves height of 4.50 m (4 ft 11 in) measured from the finished floor level or average street level (xyz is specified in the text regulations).
In your reply yesterday, you listed the following data: “Eaves height: 4.5 meters, pitched roof 38°–42°, two stories, floor area ratio: 0.4”
If a true two-story building is allowed, the eaves height of 4.50 m would not fit at all, because this means the roof’s eaves over the ground floor plus knee wall must not exceed 4.50 m. A true two-story building usually has an eaves height of at least 6.00 m (19 ft 8 in) (two full stories with a clear room height of at least 2.50 m (8 ft 2 in) plus 1–2% tolerances from the reference point – finished floor level or street level). If the building authority instead allows a calculated two-story building, it’s different, and you end up with one full story plus a maximally used knee wall up to an allowed eaves height of 4.50 m.
In my answer yesterday, I assumed you were allowed to build a genuine two-story house and just forgot to specify the ridge height. There are building areas where both one- and two-story houses are permitted close together; that’s why both the eaves and ridge heights are usually specified.
Just curious; you live and are building in my sales area. Recently, I have frequently met architects from the Bergisches Land and towards Siegerland in a similar situation, and I have always wondered what motivates homeowners to hire architects whose offices are located so far from the construction site.
You don’t have to “prove” that as a layperson—a good salesperson will explain that to you without you even having to ask.
You can assume—if all planners involved in the new build do their job properly—that with a KfW 70 energy-efficient house (equipped with an air-to-water heat pump and controlled ventilation system with heat recovery), you will have operating costs for heating and hot water of around €600–800 (depending on shower habits). A KfW 55 energy-efficient house would probably cost around €500, while a genuine passive house may only consume 15% of external energy! Now you can easily calculate for yourself if and when the additional investment for a solidly built KfW 55 or even passive house pays off.
That’s no luxury; underfloor heating is now standard, and controlled ventilation is, in my opinion, an indispensable must-have.
Yep, the latter.
Oh – that’s a “Jehovah topic,” and I wouldn’t dare give a recommendation here. Every material has its pros and cons; if you ask our builders, two will swear by hollow bricks, two by sand-lime bricks, two by lightweight concrete, and two by aerated concrete, and so on. If you ask in this forum, the majority will praise the advantages of an external thermal insulation composite system (ETICS) – even within my family, my partner and I discuss the meaningfulness of ETICS. I personally dislike that stuff because I wouldn’t want to live inside a plastic wrap; at that point, I might as well sell prefabricated houses, which is not my thing for various reasons.
Kind regards
Bauender1977 schrieb:
Thank you for answering our questions....
No need to thank me; I’m happy to do it, especially since it makes it harder for the "sellers/providers" you described to push their “trade” onto the builders; the same applies, of course, to the flip side of the coin.
Bauender1977 schrieb:
But I must also point out that the cost of 50,000 euros refers only to the bare basement without any fittings. Additional costs for wiring, wallpaper, floor coverings, and heating will be added.
That makes sense to me.
Bauender1977 schrieb:
I only estimated the earthworks as a layman. By now I’m wiser and see the costs rather in the range of 6,000 – 8,000 euros.
This estimate is realistic if your soil falls into classes 3-5; if your soil has other classifications (e.g., clay or similar), you should expect additional foundation costs up to around 8,000 euros.
Bauender1977 schrieb:
Honestly, you are confusing me now. Everyone we talked to said it would be a 1.5-story house (whatever that means).
*Chuckles* – 1.5 stories is colloquial; technically, there are only 1-, 2-, or 3- (or more) story buildings. In our work, we always refer to full floors. Regarding the data you provided:
"The development plan states: WA = general residential area, 0.4 = floor area ratio, TH 4.5 m = eaves height 4.5 meters, and SD 38–42 degrees = pitched roof 38–42°"
this clearly refers to 1 full floor (ground floor) plus knee wall (dormer wall) up to an eaves height of 4.50 m (4 ft 11 in) measured from the finished floor level or average street level (xyz is specified in the text regulations).
In your reply yesterday, you listed the following data: “Eaves height: 4.5 meters, pitched roof 38°–42°, two stories, floor area ratio: 0.4”
If a true two-story building is allowed, the eaves height of 4.50 m would not fit at all, because this means the roof’s eaves over the ground floor plus knee wall must not exceed 4.50 m. A true two-story building usually has an eaves height of at least 6.00 m (19 ft 8 in) (two full stories with a clear room height of at least 2.50 m (8 ft 2 in) plus 1–2% tolerances from the reference point – finished floor level or street level). If the building authority instead allows a calculated two-story building, it’s different, and you end up with one full story plus a maximally used knee wall up to an allowed eaves height of 4.50 m.
In my answer yesterday, I assumed you were allowed to build a genuine two-story house and just forgot to specify the ridge height. There are building areas where both one- and two-story houses are permitted close together; that’s why both the eaves and ridge heights are usually specified.
Bauender1977 schrieb:
Surroundings, but quickly accessible. Why do you ask?
Just curious; you live and are building in my sales area. Recently, I have frequently met architects from the Bergisches Land and towards Siegerland in a similar situation, and I have always wondered what motivates homeowners to hire architects whose offices are located so far from the construction site.
Bauender1977 schrieb:
We ourselves already considered that it might be economically better to build only to KfW 70 standard. But as non-experts, we couldn’t prove it.
You don’t have to “prove” that as a layperson—a good salesperson will explain that to you without you even having to ask.
Bauender1977 schrieb:
Because when you hear passive house builders talk about monthly heating costs of 50 euros, that sounds great. But if I take additional costs of 25,000 euros as a basis, the money, excluding maintenance and interest, will at best be paid back in around 30 years. That’s not so great. -->So our assumption is confirmed that it currently doesn’t pay off to build better than KfW 70. And that only applies with low-interest loans.
You can assume—if all planners involved in the new build do their job properly—that with a KfW 70 energy-efficient house (equipped with an air-to-water heat pump and controlled ventilation system with heat recovery), you will have operating costs for heating and hot water of around €600–800 (depending on shower habits). A KfW 55 energy-efficient house would probably cost around €500, while a genuine passive house may only consume 15% of external energy! Now you can easily calculate for yourself if and when the additional investment for a solidly built KfW 55 or even passive house pays off.
Bauender1977 schrieb:
The only “luxuries” we want in this regard are underfloor heating and a central controlled ventilation system with heat and humidity recovery. But a little economic inefficiency is acceptable if it supports the German industry.
That’s no luxury; underfloor heating is now standard, and controlled ventilation is, in my opinion, an indispensable must-have.
Bauender1977 schrieb:
What do you mean when you say that with a monolithic wall, even the basement doesn’t hurt as much anymore? Leaving it out or including the cost in the budget?
Yep, the latter.
Bauender1977 schrieb:
Which material should the monolithic wall ideally be made of? T8/T9 or even T7? Aerated concrete (Ytong Planblock W PP)?
Oh – that’s a “Jehovah topic,” and I wouldn’t dare give a recommendation here. Every material has its pros and cons; if you ask our builders, two will swear by hollow bricks, two by sand-lime bricks, two by lightweight concrete, and two by aerated concrete, and so on. If you ask in this forum, the majority will praise the advantages of an external thermal insulation composite system (ETICS) – even within my family, my partner and I discuss the meaningfulness of ETICS. I personally dislike that stuff because I wouldn’t want to live inside a plastic wrap; at that point, I might as well sell prefabricated houses, which is not my thing for various reasons.
Kind regards
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