Hi everyone,
We had a really exhausting day today.
We had two meetings at the prefabricated house center in Mannheim.
In the morning, we visited Keitel-Haus, and in the afternoon, Hanse Haus.
Our problem is: after meeting with Keitel-Haus, we thought we finally had clarity. But Hanse claims exactly the opposite.
At Keitel-Haus, this was our second long discussion, and this time we went into detail with a precise written quote and detailed descriptions of the individual building materials.
Now to the different statements, and we would appreciate your opinions as well.
You have the experience and are independent.
Exterior wall:
Keitel-Haus: vapor-permeable wall WITHOUT a vapor barrier (vapor retarder).
Including:
60mm (2.4 inches) wood fiber insulation board
200mm (7.9 inches) timber frame construction
200mm (7.9 inches) mineral fiber insulation
Wall thickness 29.2cm (11.5 inches)
Hanse: vapor-permeable wall WITH vapor retarder
Including:
150mm (5.9 inches) thermal insulation, thermal conductivity class 032
8mm (0.3 inches) OSB board
125mm (4.9 inches) timber frame construction (with mineral insulation)
8mm (0.3 inches) OSB board
vapor-permeable vapor retarder fleece
12.5mm (0.5 inches) gypsum board
So,
Keitel-Haus says: We build a proper vapor-permeable wall, so without any vapor retarders. This allows moisture to really escape outside, preventing mold growth.
Hanse says: That’s nonsense, there are no houses that can "breathe". We have a vapor retarder because we want to hold back water vapor, i.e., moisture. We don’t want it to enter the wall, as it would cause damage. Without a barrier, mold would eventually develop.
What is correct here?
Topic 2
Heating technology / ventilation:
Keitel-Haus:
They considered our wishes and said that while they think controlled residential ventilation is good, they do not recommend controlled ventilation with heat recovery. I don’t remember exactly why, but there was a lengthy explanation. Anyway, probably because of underfloor heating, we wanted a heat pump.
Hanse:
They tried to persuade us to get a different kind of heat pump and insisted it would be better to have controlled ventilation WITH heat recovery.
It would save energy, and windows can still be opened (which we want, especially at night while sleeping and sometimes in summer).
If I remember correctly, I recently read only negative things about that kind of heat pump, and that it would financially disadvantage us.
Hanse says: Nonsense. If the house is built properly and the system is installed correctly, this kind of heat pump is best, and they can ensure it is the most cost-effective.
Topic 3
KfW 40/55 standards
Keitel-Haus:
KfW 55 is optimal and can be achieved without problems according to our requirements (photovoltaics, underfloor heating, heat pump, vapor-permeable wall).
KfW 40 requires too much effort and is much too expensive. The savings wouldn’t justify it.
Hanse:
KfW 40 or better yet Passive House, since from 2020 Passive House standard is mandatory anyway.
The difference from KfW 55 to KfW 40 would only be about €9000 and corresponds to additional insulation under the slab and roof. No extra technology would be needed, and the savings would be enormous!
Their walls already meet KfW 40 as standard.
Topic 4:
Exterior wall insulation
Keitel-Haus builds with wood fiber insulation board. Styrofoam (EPS) is standard but not recommended because it is vapor-tight. That’s why they offer a better "open" wall.
I know Styrofoam is extremely poor in fire performance. I don’t like it at all.
Hanse:
I had no clear answer; I couldn’t really get details. They just said Styrofoam is not so bad, and their thermal insulation contains some graphite.
It seemed to me like Styrofoam with graphite additives or something similar.
I know, lots of questions again.
I have already spent many hours reading but still don’t feel much wiser.
These topics are very complex and sometimes a bit beyond me.
From the feeling we have, we would build with Keitel-Haus.
The Hanse representative was arrogant and "aggressive." I even almost argued with him because he was unwilling to discuss most points, including providing a written offer. He said he only bothers if he knows you really want to build with them. For me, a comparison makes no sense without different offers and service descriptions to compare.
We also looked at Fingerhut, but after 6 weeks they still haven’t provided an offer. So that’s a no-go for us. The "salesperson" seems to prefer working his side job (entertainer).
Rensch-Haus gave us many verbal promises that everything would be possible (of course, for extra money, everything is possible), but 90% of what should have been standard was not in the service description.
We had a really exhausting day today.
We had two meetings at the prefabricated house center in Mannheim.
In the morning, we visited Keitel-Haus, and in the afternoon, Hanse Haus.
Our problem is: after meeting with Keitel-Haus, we thought we finally had clarity. But Hanse claims exactly the opposite.
At Keitel-Haus, this was our second long discussion, and this time we went into detail with a precise written quote and detailed descriptions of the individual building materials.
Now to the different statements, and we would appreciate your opinions as well.
You have the experience and are independent.
Exterior wall:
Keitel-Haus: vapor-permeable wall WITHOUT a vapor barrier (vapor retarder).
Including:
60mm (2.4 inches) wood fiber insulation board
200mm (7.9 inches) timber frame construction
200mm (7.9 inches) mineral fiber insulation
Wall thickness 29.2cm (11.5 inches)
Hanse: vapor-permeable wall WITH vapor retarder
Including:
150mm (5.9 inches) thermal insulation, thermal conductivity class 032
8mm (0.3 inches) OSB board
125mm (4.9 inches) timber frame construction (with mineral insulation)
8mm (0.3 inches) OSB board
vapor-permeable vapor retarder fleece
12.5mm (0.5 inches) gypsum board
So,
Keitel-Haus says: We build a proper vapor-permeable wall, so without any vapor retarders. This allows moisture to really escape outside, preventing mold growth.
Hanse says: That’s nonsense, there are no houses that can "breathe". We have a vapor retarder because we want to hold back water vapor, i.e., moisture. We don’t want it to enter the wall, as it would cause damage. Without a barrier, mold would eventually develop.
What is correct here?
Topic 2
Heating technology / ventilation:
Keitel-Haus:
They considered our wishes and said that while they think controlled residential ventilation is good, they do not recommend controlled ventilation with heat recovery. I don’t remember exactly why, but there was a lengthy explanation. Anyway, probably because of underfloor heating, we wanted a heat pump.
Hanse:
They tried to persuade us to get a different kind of heat pump and insisted it would be better to have controlled ventilation WITH heat recovery.
It would save energy, and windows can still be opened (which we want, especially at night while sleeping and sometimes in summer).
If I remember correctly, I recently read only negative things about that kind of heat pump, and that it would financially disadvantage us.
Hanse says: Nonsense. If the house is built properly and the system is installed correctly, this kind of heat pump is best, and they can ensure it is the most cost-effective.
Topic 3
KfW 40/55 standards
Keitel-Haus:
KfW 55 is optimal and can be achieved without problems according to our requirements (photovoltaics, underfloor heating, heat pump, vapor-permeable wall).
KfW 40 requires too much effort and is much too expensive. The savings wouldn’t justify it.
Hanse:
KfW 40 or better yet Passive House, since from 2020 Passive House standard is mandatory anyway.
The difference from KfW 55 to KfW 40 would only be about €9000 and corresponds to additional insulation under the slab and roof. No extra technology would be needed, and the savings would be enormous!
Their walls already meet KfW 40 as standard.
Topic 4:
Exterior wall insulation
Keitel-Haus builds with wood fiber insulation board. Styrofoam (EPS) is standard but not recommended because it is vapor-tight. That’s why they offer a better "open" wall.
I know Styrofoam is extremely poor in fire performance. I don’t like it at all.
Hanse:
I had no clear answer; I couldn’t really get details. They just said Styrofoam is not so bad, and their thermal insulation contains some graphite.
It seemed to me like Styrofoam with graphite additives or something similar.
I know, lots of questions again.
I have already spent many hours reading but still don’t feel much wiser.
These topics are very complex and sometimes a bit beyond me.
From the feeling we have, we would build with Keitel-Haus.
The Hanse representative was arrogant and "aggressive." I even almost argued with him because he was unwilling to discuss most points, including providing a written offer. He said he only bothers if he knows you really want to build with them. For me, a comparison makes no sense without different offers and service descriptions to compare.
We also looked at Fingerhut, but after 6 weeks they still haven’t provided an offer. So that’s a no-go for us. The "salesperson" seems to prefer working his side job (entertainer).
Rensch-Haus gave us many verbal promises that everything would be possible (of course, for extra money, everything is possible), but 90% of what should have been standard was not in the service description.
The savings would be huge – with 450€ annual heating costs and a 9000€ additional cost – that’s a good deal.
I’m sure that the Keitel wall manufacturer also doesn’t want the mineral wool to develop mold, so I assume the inner fiberboard is sealed as well… (I’m happy to be corrected).
By the way, if the new building develops mold after moving in, something was done wrong.
I’m sure that the Keitel wall manufacturer also doesn’t want the mineral wool to develop mold, so I assume the inner fiberboard is sealed as well… (I’m happy to be corrected).
By the way, if the new building develops mold after moving in, something was done wrong.
Mycraft schrieb:
You have concerns about the polystyrene and its fire behavior??? But you want to build a wooden house? Sorry, but you might want to check again on the fire performance of these materials. Wood actually has some of the best fire properties and a long resistance time. Polystyrene is simply very dangerous and can cause your entire house to burn down within seconds.
B
Bauexperte18 Nov 2015 10:54Hello,
The longest resistance time is achieved by concrete, provided it is not reinforced with steel. However, who would want to live in a concrete bunker?
Regards, Bauexperte
305er schrieb:That is not entirely correct; the accurate point is that a charred wood surface (not veneers, but for example roof battens) slows down the fire process.
Wood has among the best fire properties and a long resistance time.
The longest resistance time is achieved by concrete, provided it is not reinforced with steel. However, who would want to live in a concrete bunker?
305er schrieb:Certainly not in seconds, but once it is burning, it is advisable to escape from the fumes.
Styrofoam is simply very dangerous and will burn your entire house down in seconds.
Regards, Bauexperte
I can only agree with the construction expert... and it takes quite a lot for the polystyrene to catch fire... just because it burns in a lab when you hold a lighter to it doesn’t mean you’ll see the same effect on an exterior wall.
Most facade fires, by the way, are actually caused by burning trash bins...
But anyway, go ahead and build... and it’s better if you inform yourself first... Polystyrene that burns instantly (it’s probably soaked with an accelerant)... otherwise, your statement can’t be explained.
Most facade fires, by the way, are actually caused by burning trash bins...
But anyway, go ahead and build... and it’s better if you inform yourself first... Polystyrene that burns instantly (it’s probably soaked with an accelerant)... otherwise, your statement can’t be explained.
B
Bieber081518 Nov 2015 20:38305er schrieb:
He only said that styrofoam wasn’t so bad and that their thermal insulation was something with graphite.
It seemed to me like it’s styrofoam, just filled with graphite or something. He was probably referring to NEOPOR (R), a high-performance expanded polystyrene (EPS) insulation material that contains graphite particles. This insulation has a higher thermal performance at the same thickness compared to conventional EPS insulation.
In my opinion, anyone concerned about burning styrofoam should avoid graphite insulation (personally, I believe this fear is unfounded, but that is beside the point here).
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