ᐅ KfW40 standard, heat pump / solar system, timber frame / solid construction?
Created on: 25 Feb 2009 16:42
A
AzaleeHello, forum!
The question above naturally comes up again and again. In general, there is an overwhelming amount of information on the topic of construction methods. Our problem with this is that the information and/or experience reports are often "biased," meaning they usually come from timber construction or masonry suppliers directly or from their agents.
After extensive research, we have the impression that both construction methods have their pros and cons, but we (so far) do not feel able to make a decision for ourselves. We want a house that meets KfW40 standard, is very well insulated, heated with a heat pump, equipped with a solar system for at least hot water, and has a mechanical ventilation system with heat recovery. Not least because of the planned location on a gentle north-facing slope, many and large windows are important (floor-to-ceiling where possible).
Here is what I hear/read about timber / masonry:
Masonry houses (brick or block construction, stone on stone)
+ tend to retain their value better for resale, are more value-stable,
+ provide better sound insulation, which in timber construction is only achieved with special additional effort (to what extent is this now standard?),
+ stay cooler longer in summer,
- have a longer construction time, need drying.
Timber houses (mainly timber frame construction)
+ generally "healthier" (indoor climate, natural materials...),
+ require thinner walls for the same insulation,
+ are built faster,
- heat up quickly in summer,
- are more prone to noise transmission.
The list could go on, but these points (along with price) are particularly important to us.
What matters to us:
It would be great if you could give us advice based on this on which construction method would be more suitable for us. Certainly, both timber and masonry can meet our requirements, but perhaps more investment or specific considerations and optimizations are needed with one method than with the other.
If any important information is missing, I’ll be happy to provide it.
Thanks and best regards
Christiane
The question above naturally comes up again and again. In general, there is an overwhelming amount of information on the topic of construction methods. Our problem with this is that the information and/or experience reports are often "biased," meaning they usually come from timber construction or masonry suppliers directly or from their agents.
After extensive research, we have the impression that both construction methods have their pros and cons, but we (so far) do not feel able to make a decision for ourselves. We want a house that meets KfW40 standard, is very well insulated, heated with a heat pump, equipped with a solar system for at least hot water, and has a mechanical ventilation system with heat recovery. Not least because of the planned location on a gentle north-facing slope, many and large windows are important (floor-to-ceiling where possible).
Here is what I hear/read about timber / masonry:
Masonry houses (brick or block construction, stone on stone)
+ tend to retain their value better for resale, are more value-stable,
+ provide better sound insulation, which in timber construction is only achieved with special additional effort (to what extent is this now standard?),
+ stay cooler longer in summer,
- have a longer construction time, need drying.
Timber houses (mainly timber frame construction)
+ generally "healthier" (indoor climate, natural materials...),
+ require thinner walls for the same insulation,
+ are built faster,
- heat up quickly in summer,
- are more prone to noise transmission.
The list could go on, but these points (along with price) are particularly important to us.
What matters to us:
- very good insulation ("insulate first, then heat")
- good soundproofing, especially inside the house, because we (and later probably the children) make a lot of music
- the house stays pleasantly cool in summer (noticeably cooler than outside, though this probably also depends on the ventilation; however, we do not want air conditioning)
- a floor plan tailored to our plot (gentle north-facing slope, careful room and terrace orientation important for the layout, e.g., a slanted living/dining area conceivable, one or two balconies upstairs, large windows, one or two bay windows, etc.)
- at least a partial basement (built into the slope), though preferably a full basement
- our saltwater aquarium. Several liters of water evaporate daily and reportedly a minimal salt content builds up in the air with saltwater, even though it’s predominantly pure water that evaporates at first.
It would be great if you could give us advice based on this on which construction method would be more suitable for us. Certainly, both timber and masonry can meet our requirements, but perhaps more investment or specific considerations and optimizations are needed with one method than with the other.
If any important information is missing, I’ll be happy to provide it.
Thanks and best regards
Christiane
I think both approaches are possible.
What I find more important is building with vapor-permeable materials. This means that moisture can circulate relatively freely and balance out.
As a relative layperson in construction and someone currently building a timber house, I would recommend a vapor-permeable timber construction or a brick option with natural insulation made from zeolite or wood fiber.
Personally, I don’t like systems with polystyrene. I believe you can feel the difference—not in the show homes of prefab manufacturers, as those are always well ventilated. More likely in the houses of those who have to make savings somewhere.
Solid houses (masonry)
+ tend to retain their value better for potential resale, are more durable in terms of value. That is true, but this may change in 10 years.
+ have better sound insulation, which in timber houses can only be achieved with additional special measures (to what extent is this standard now?).
Timber houses are generally worse in this regard due to having less mass.
+ stay cooler in summer. That doesn’t have to be the case—it depends on the insulation.
- have longer construction times and need to dry. Correct.
Timber houses (mainly timber frame)
+ are generally "healthier" (indoor climate, natural materials, etc.). (I hope so.)
+ require less wall thickness for the same insulation. Yep.
+ are built faster. (But not planned faster.)
- heat up quickly in summer (see above).
- have less sound insulation. (Certainly somewhat more so—if sensitive, acoustic ceilings and other measures can help.)
Regarding moisture evaporation—how about a clay plaster that can absorb and release a lot of moisture? At night, without lights, less evaporation occurs, allowing moisture levels to balance out again.
Otherwise, perhaps consider a controlled mechanical ventilation system—it keeps every room dry.
However, I would inquire further about how this interacts with salt.
Does that help you a little?
Personally, I would have liked to build with brick filled with zeolite and natural additional insulation—but that would have become somewhat expensive.
What I find more important is building with vapor-permeable materials. This means that moisture can circulate relatively freely and balance out.
As a relative layperson in construction and someone currently building a timber house, I would recommend a vapor-permeable timber construction or a brick option with natural insulation made from zeolite or wood fiber.
Personally, I don’t like systems with polystyrene. I believe you can feel the difference—not in the show homes of prefab manufacturers, as those are always well ventilated. More likely in the houses of those who have to make savings somewhere.
Solid houses (masonry)
+ tend to retain their value better for potential resale, are more durable in terms of value. That is true, but this may change in 10 years.
+ have better sound insulation, which in timber houses can only be achieved with additional special measures (to what extent is this standard now?).
Timber houses are generally worse in this regard due to having less mass.
+ stay cooler in summer. That doesn’t have to be the case—it depends on the insulation.
- have longer construction times and need to dry. Correct.
Timber houses (mainly timber frame)
+ are generally "healthier" (indoor climate, natural materials, etc.). (I hope so.)
+ require less wall thickness for the same insulation. Yep.
+ are built faster. (But not planned faster.)
- heat up quickly in summer (see above).
- have less sound insulation. (Certainly somewhat more so—if sensitive, acoustic ceilings and other measures can help.)
Regarding moisture evaporation—how about a clay plaster that can absorb and release a lot of moisture? At night, without lights, less evaporation occurs, allowing moisture levels to balance out again.
Otherwise, perhaps consider a controlled mechanical ventilation system—it keeps every room dry.
However, I would inquire further about how this interacts with salt.
Does that help you a little?
Personally, I would have liked to build with brick filled with zeolite and natural additional insulation—but that would have become somewhat expensive.
H
Honigkuchen26 Feb 2009 09:10Hello Azalee and Joerg, I am replying (in dark red) directly to Joerg’s comments (in blue) regarding your questions (in black).
Sure, both are always possible, but timber construction is almost always more expensive.
Hmm, you should have a well-insulated building envelope; the indoor climate then becomes particularly important, and especially for KfW40 or better houses, it is definitely recommended to install a controlled ventilation system. This removes moisture and creates a comfortable living environment.
I don’t know zeolite yet, but I agree with you on polystyrene. Please also avoid mineral wool. Anything harmful or potentially harmful—whether when installing the insulation or afterward through off-gassing or similar—should not be used.
Or with polystyrene: If you roughly lean your bike against the exterior wall, you get a dent in the polystyrene exterior insulation… no, no…
There are also monolithic construction methods, meaning a single solid block without vulnerable external insulation systems (ETICS—External Thermal Insulation Composite Systems), but very thick and highly insulating.
So, now it’s getting colorful
Solid Houses (masonry)
+ tend to retain their value better if resold; they are more durable in value.
That’s probably true, but this might change in 10 years.
Architects and banks say this is very likely to remain the case.
This is because solid houses are generally easier to sell. Exceptions are probably solid timber houses with a great view of mountains or lakes—that fits again.
+ have better sound insulation, which requires special additional effort in timber houses (to what extent is this now standard?)
Timber houses are usually worse due to having less mass.
Unfortunately, that’s correct. However, I don’t know how it is with solid timber houses—whether they also have good sound insulation. But solid timber houses are very expensive anyway, so that probably wouldn’t be an option.
+ stay cooler in summer
That doesn’t have to be the case—it depends on the insulation.
Not only on the insulation, but also on the windows; fundamentally, wood is a poor conductor of heat. Sound transmission also depends on fiber direction. Generally, in southern regions, in houses probably not built according to energy saving regulations, I felt more comfortable heat-wise in masonry houses than in timber houses.
- have a longer construction time and need to dry
True
Not (always) true.
There are now also solid prefabricated houses; parts are prefabricated in the factory and dry there already. Depending on the material and whether there is a basement, the construction time of a solid house can be only a few days (!) or 3–4 months with some providers. With traditional masonry, yes, it can take 6 months, but when I read what problems some people have with their timber-frame prefab house provider, causing delays that can extend the process to a year...
Because you have a controlled ventilation system with heat recovery (if it’s worthwhile relative to the electricity used) in such a well-insulated house, any remaining moisture from construction will be vented out; so you don’t have to worry about disadvantages from that.
Timber Houses (mainly timber frame)
+ are generally "healthier" (indoor climate, natural materials...)
(I hope so)
Yes, that’s basically true—provided the wood hasn’t been treated with harmful substances...
But there are also bricks claiming to create a healthy indoor climate.
+ need thinner walls for the same insulation
Yep
For the same U-value, yes, that's correct.
+ are built faster
(But not planned faster)
As noted, they are not always faster to build.
- heat up quickly in summer
(see above)
Apart from that, if you choose a heat pump: it can heat and also cool...
- are noisy inside
(Surely somewhat more – if you’re sensitive, you can also use acoustic ceilings, etc.)
Timber-frame houses are not just somewhat but much noisier; there have been numerous independent tests.
As for acoustic ceilings… hmm… you would need to do that for the walls as well. After all, you don’t just hear noise from above but also from the sides.
That’s very good advice, I fully support that.
As mentioned, that should now be mandatory in well-insulated houses.
Unfortunately, I don’t know about that.
Best regards
Honigkuchen
JOERG24 schrieb:
I think both options are possible.
Sure, both are always possible, but timber construction is almost always more expensive.
JOERG24 schrieb:
More important, I think, is that they build with vapor-permeable materials. That means moisture can circulate and balance relatively freely.
Hmm, you should have a well-insulated building envelope; the indoor climate then becomes particularly important, and especially for KfW40 or better houses, it is definitely recommended to install a controlled ventilation system. This removes moisture and creates a comfortable living environment.
JOERG24 schrieb:
As a relative construction layperson and current timber house builder, I would recommend a vapor-permeable timber construction or a brick variant with natural insulation like zeolite or wood fiber.
Personally, I don’t like systems with polystyrene. I think you can also feel the difference. Not in the show homes of prefab manufacturers, as they are always well ventilated. More in the houses of those who have to save somewhere.
I don’t know zeolite yet, but I agree with you on polystyrene. Please also avoid mineral wool. Anything harmful or potentially harmful—whether when installing the insulation or afterward through off-gassing or similar—should not be used.
Or with polystyrene: If you roughly lean your bike against the exterior wall, you get a dent in the polystyrene exterior insulation… no, no…
There are also monolithic construction methods, meaning a single solid block without vulnerable external insulation systems (ETICS—External Thermal Insulation Composite Systems), but very thick and highly insulating.
So, now it’s getting colorful
Solid Houses (masonry)
+ tend to retain their value better if resold; they are more durable in value.
That’s probably true, but this might change in 10 years.
Architects and banks say this is very likely to remain the case.
This is because solid houses are generally easier to sell. Exceptions are probably solid timber houses with a great view of mountains or lakes—that fits again.
+ have better sound insulation, which requires special additional effort in timber houses (to what extent is this now standard?)
Timber houses are usually worse due to having less mass.
Unfortunately, that’s correct. However, I don’t know how it is with solid timber houses—whether they also have good sound insulation. But solid timber houses are very expensive anyway, so that probably wouldn’t be an option.
+ stay cooler in summer
That doesn’t have to be the case—it depends on the insulation.
Not only on the insulation, but also on the windows; fundamentally, wood is a poor conductor of heat. Sound transmission also depends on fiber direction. Generally, in southern regions, in houses probably not built according to energy saving regulations, I felt more comfortable heat-wise in masonry houses than in timber houses.
- have a longer construction time and need to dry
True
Not (always) true.
There are now also solid prefabricated houses; parts are prefabricated in the factory and dry there already. Depending on the material and whether there is a basement, the construction time of a solid house can be only a few days (!) or 3–4 months with some providers. With traditional masonry, yes, it can take 6 months, but when I read what problems some people have with their timber-frame prefab house provider, causing delays that can extend the process to a year...
Because you have a controlled ventilation system with heat recovery (if it’s worthwhile relative to the electricity used) in such a well-insulated house, any remaining moisture from construction will be vented out; so you don’t have to worry about disadvantages from that.
Timber Houses (mainly timber frame)
+ are generally "healthier" (indoor climate, natural materials...)
(I hope so)
Yes, that’s basically true—provided the wood hasn’t been treated with harmful substances...
But there are also bricks claiming to create a healthy indoor climate.
+ need thinner walls for the same insulation
Yep
For the same U-value, yes, that's correct.
+ are built faster
(But not planned faster)
As noted, they are not always faster to build.
- heat up quickly in summer
(see above)
Apart from that, if you choose a heat pump: it can heat and also cool...
- are noisy inside
(Surely somewhat more – if you’re sensitive, you can also use acoustic ceilings, etc.)
Timber-frame houses are not just somewhat but much noisier; there have been numerous independent tests.
As for acoustic ceilings… hmm… you would need to do that for the walls as well. After all, you don’t just hear noise from above but also from the sides.
JOERG24 schrieb:
Regarding their moisture evaporation—how about clay plaster, which can absorb and release a lot of moisture? At night, without lamps, not much evaporates and it can balance out.
That’s very good advice, I fully support that.
JOERG24 schrieb:
Otherwise, maybe a controlled ventilation system—it dries every room.
As mentioned, that should now be mandatory in well-insulated houses.
JOERG24 schrieb:
As for how it reacts with salt, I would inquire.
Unfortunately, I don’t know about that.
Best regards
Honigkuchen
Just a small additional note...
I would avoid cooling in the summer – somehow, I can’t get comfortable with the idea of cooling using electricity. After all, that’s what the heat pump requires.
A ventilation system is a double-edged sword. Some consultants and building biologists advised against it. In the end, we decided not to install one either. Everyone warned us to be cautious if we are sensitive to dry air. The heat exchanger necessary for heat recovery inevitably removes moisture from the air.
So, the air may need to be artificially humidified. By now, I know one or two people who manage this with hydroponic plants and frequent watering.
I’m simply a person who prefers natural ventilation. Now and then, I have to fling open a window. It doesn’t even have much to do with stale air. At least in winter, I’d have to restrain myself a bit to fully benefit from the energy-saving effect.
Maybe I’m somewhat biased. I once dismantled a ventilation system. The amount of buildup inside was alarming. Usually, you can’t properly clean these systems. Everything that grows and thrives inside then spreads throughout the entire house. The thought of that just doesn’t sit well with me. By the way, this is also why I don’t like central vacuum systems.
One more small point: these systems are never completely draft-free, and they also create an acoustic connection between the rooms.
Economically, however, they are certainly sensible.
I would avoid cooling in the summer – somehow, I can’t get comfortable with the idea of cooling using electricity. After all, that’s what the heat pump requires.
A ventilation system is a double-edged sword. Some consultants and building biologists advised against it. In the end, we decided not to install one either. Everyone warned us to be cautious if we are sensitive to dry air. The heat exchanger necessary for heat recovery inevitably removes moisture from the air.
So, the air may need to be artificially humidified. By now, I know one or two people who manage this with hydroponic plants and frequent watering.
I’m simply a person who prefers natural ventilation. Now and then, I have to fling open a window. It doesn’t even have much to do with stale air. At least in winter, I’d have to restrain myself a bit to fully benefit from the energy-saving effect.
Maybe I’m somewhat biased. I once dismantled a ventilation system. The amount of buildup inside was alarming. Usually, you can’t properly clean these systems. Everything that grows and thrives inside then spreads throughout the entire house. The thought of that just doesn’t sit well with me. By the way, this is also why I don’t like central vacuum systems.
One more small point: these systems are never completely draft-free, and they also create an acoustic connection between the rooms.
Economically, however, they are certainly sensible.
H
Honigkuchen26 Feb 2009 09:44JOERG24 schrieb:
I would avoid cooling in the summer – Somehow, I can’t get comfortable with the idea of cooling powered by electricity. After all, the heat pump requires power.I personally haven’t warmed up to heat pumps either – I basically don’t like them.
JOERG24 schrieb:
A ventilation system is a double-edged sword. Some consultants and building biologists advised us against it. In the end, we didn’t install one either. Everyone advised us to be cautious if we are sensitive to dry air. The heat exchanger necessary for heat recovery inevitably removes moisture from the air.At the same time, fresh air is supplied from outside; with a simple air conditioner, you’re right, the air does get dry. But with a modern, high-tech ventilation system with heat recovery, that’s simply not true.
JOERG24 schrieb:
If necessary, the air must be artificially humidified again. By now, I know one or two people who have managed this with hydroponics and frequent watering.As you rightly pointed out: Clay plaster also regulates humidity very well, if needed.
Untreated wood, which can absorb moisture, in damp rooms like the bathroom, also takes up water and releases it back into the room.
JOERG24 schrieb:
I’m simply someone who appreciates fresh air. From time to time, I need to throw the window wide open. It’s not necessarily about stale air. At least in winter, I would have to control myself to fully benefit from the energy savings.With the system, you save a significant amount on heating costs.
In summer, my windows and patio doors would definitely be open too; but for allergy sufferers (I’m allergic to dust and some pollen), such a system is a blessing.
JOERG24 schrieb:
Maybe I’m a bit biased. I once dismantled a ventilation system. You wouldn’t believe what accumulated inside. Normally, you can’t clean it. Everything that grows there then spreads throughout the whole house. The thought just doesn’t sit well with me.Then it was a really poor and cheap ventilation system, either without a filter or with one that wasn’t checked and replaced annually as recommended, and perhaps not even installed professionally by experts.
All three architects we contacted (with between 10 and 25 years of experience) strongly recommend such a system to us.
Today’s systems don’t accumulate dirt inside; everything is caught in the filter, which you replace regularly.
Of course, it depends on the system, but we will definitely make sure to install a system with relevant quality certifications that has been thoroughly tested by various independent bodies, consumer organizations, etc.
We are also contacting families who have been living with such systems for several years; we have contact details of architects and will ask them about their experience in terms of cleanliness, filters, and so on.
JOERG24 schrieb:
By the way, this is also why I don’t like central vacuum systems.I consider them unnecessary and too expensive for hard floors (tiles/wood).
If you have underfloor heating and a controlled ventilation system, there is hardly any dust; a weekly damp mop is enough.
There are also small, handy vacuum cleaners available, so carrying them between floors wouldn’t be a problem if you have a carpet in just one room that needs vacuuming.
JOERG24 schrieb:
One more small point: these systems are never completely draft-free, and they create an acoustic connection between rooms.It really depends on the system and how the supply and exhaust ducts are designed; there are very different types regarding how air comes in and goes out, and which rooms are involved.
Do your research—there are incredible differences, so you have to be very careful and selective when choosing. All the potential weaknesses you mentioned should be clarified in advance and verified through appropriate tests, expert reports, and user feedback.
Best regards,
Honigkuchen
+ stay cooler for longer in summer,
That’s not necessarily true – it depends on the insulation.
Not just the insulation, also the windows; but basically wood is a poor conductor of heat. The sound transmission also depends on the grain direction. Generally, in southern regions, with houses definitely not built according to energy-saving regulations, I felt more comfortable in stone houses than in wooden ones during heat.
Roller shutters are the magic word. For me, they are simply summer heat protection. Nice ones made of aluminum and insulated so the heat doesn’t come in as much.
The grain direction detail is correct – nice technical detail, I like it.
I think the question about construction time is pointless – it always depends on the supplier. Looking at the Massivbau AG example, the same issues appear everywhere. Whether solid construction, prefabricated, timber, or developer-built.
Building is one of the last true adventures.
Often, I think homeowners themselves are not adequately prepared and some decisions need to be corrected quite late.
I was truly shocked when many advisors said that we had dealt with the topic extraordinarily intensively. Many seem not to engage with the important technical details at all.
That’s not necessarily true – it depends on the insulation.
Not just the insulation, also the windows; but basically wood is a poor conductor of heat. The sound transmission also depends on the grain direction. Generally, in southern regions, with houses definitely not built according to energy-saving regulations, I felt more comfortable in stone houses than in wooden ones during heat.
Roller shutters are the magic word. For me, they are simply summer heat protection. Nice ones made of aluminum and insulated so the heat doesn’t come in as much.
The grain direction detail is correct – nice technical detail, I like it.
I think the question about construction time is pointless – it always depends on the supplier. Looking at the Massivbau AG example, the same issues appear everywhere. Whether solid construction, prefabricated, timber, or developer-built.
Building is one of the last true adventures.
Often, I think homeowners themselves are not adequately prepared and some decisions need to be corrected quite late.
I was truly shocked when many advisors said that we had dealt with the topic extraordinarily intensively. Many seem not to engage with the important technical details at all.
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