ᐅ Slab foundation with concrete core activation. What are your thoughts?
Created on: 19 Dec 2017 12:37
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Peter L
Hello everyone,
If everything goes well, we plan to start building our own home next year, in 2018. We want to contract the trades independently and also carry out some parts ourselves. Here are some key details:
Approximately 200m² (2,150 sq ft) of living space without a basement. Underfloor heating with hardwood floors and an air-source heat pump. Ideally, a photovoltaic system will be installed on the roof and an energy storage unit in the utility room (KFW40+ standard). We are planning to use calcium silicate bricks with an external insulation system made of Multipor (cost considerations). This is just for your information and not meant to be part of the discussion.
I have spent quite some time researching ground slabs and have read a lot. It puzzles me that there are so few experience reports on Swedish slabs or similar systems. There are only one or two threads on this topic in this forum. It might be due to the tendency to report online mainly when one is dissatisfied, or perhaps people don’t realize when they are building a prefabricated house. Either way, most of the posts I found are five years or older. Often, people are unfamiliar with the Swedish slab, and what is not well known or regarded as proven tends to be viewed negatively. I was able to clarify many criticisms with some research and therefore we are still leaning towards the Swedish slab, although we are not completely certain, as I have never read a clear recommendation.
1. Costs
A frequently mentioned concern is the cost, so I will keep it brief. If you include the underfloor heating and screed in a conventional slab, the cost difference becomes less significant. The Swedish slab, however, offers significantly better insulation and thus saves money over time.
2. Speed
There was a criticism in this forum that the Futura ground slab reacts very slowly. In a building with Futura on the ground floor and a conventional underfloor heating with screed on the upper floor, the upper floor warms up within about 30 minutes, while it takes around 6 hours on the ground floor. Well, concrete is much more inert and it naturally takes longer for the heat to be noticeable. The advantage, however, is that concrete retains heat longer. Each person must decide how important it is to be able to adjust the temperature quickly. I wouldn’t necessarily consider this a disadvantage.
3. Impact noise
I read briefly that impact sound insulation might be worse. How significant is this on the ground floor? Is this really the case and are there current solutions to reduce it?
4. Maintenance
I keep reading that if something breaks, it’s hopeless. I can imagine it’s easier to break open screed than concrete, but to be honest – why would you want to do that? Isn’t it more of a theoretical problem? Suppose a pipe breaks for some unknown reason, water will continue to flow and the concrete won’t dissolve or degrade because of that, right? I don’t fully understand this criticism.
5. Time savings
No criticism here, but a Swedish slab doesn’t require drying time, which speeds up the construction process and eliminates moisture in the house.
So far, I don’t see any significant negatives, though I am not an expert and can only judge based on the information I have. I would therefore appreciate an expert opinion. Are there any mistakes one can make when pouring a Swedish slab, and are there other disadvantages I might not have considered?
What would be the advantages of a conventional slab? I imagine it can also be insulated to achieve similar benefits in that respect. Then the main difference would be the drying time for the screed. Perhaps there are other considerations when building with calcium silicate bricks plus external insulation.
I look forward to your opinions.
Peter L
If everything goes well, we plan to start building our own home next year, in 2018. We want to contract the trades independently and also carry out some parts ourselves. Here are some key details:
Approximately 200m² (2,150 sq ft) of living space without a basement. Underfloor heating with hardwood floors and an air-source heat pump. Ideally, a photovoltaic system will be installed on the roof and an energy storage unit in the utility room (KFW40+ standard). We are planning to use calcium silicate bricks with an external insulation system made of Multipor (cost considerations). This is just for your information and not meant to be part of the discussion.
I have spent quite some time researching ground slabs and have read a lot. It puzzles me that there are so few experience reports on Swedish slabs or similar systems. There are only one or two threads on this topic in this forum. It might be due to the tendency to report online mainly when one is dissatisfied, or perhaps people don’t realize when they are building a prefabricated house. Either way, most of the posts I found are five years or older. Often, people are unfamiliar with the Swedish slab, and what is not well known or regarded as proven tends to be viewed negatively. I was able to clarify many criticisms with some research and therefore we are still leaning towards the Swedish slab, although we are not completely certain, as I have never read a clear recommendation.
1. Costs
A frequently mentioned concern is the cost, so I will keep it brief. If you include the underfloor heating and screed in a conventional slab, the cost difference becomes less significant. The Swedish slab, however, offers significantly better insulation and thus saves money over time.
2. Speed
There was a criticism in this forum that the Futura ground slab reacts very slowly. In a building with Futura on the ground floor and a conventional underfloor heating with screed on the upper floor, the upper floor warms up within about 30 minutes, while it takes around 6 hours on the ground floor. Well, concrete is much more inert and it naturally takes longer for the heat to be noticeable. The advantage, however, is that concrete retains heat longer. Each person must decide how important it is to be able to adjust the temperature quickly. I wouldn’t necessarily consider this a disadvantage.
3. Impact noise
I read briefly that impact sound insulation might be worse. How significant is this on the ground floor? Is this really the case and are there current solutions to reduce it?
4. Maintenance
I keep reading that if something breaks, it’s hopeless. I can imagine it’s easier to break open screed than concrete, but to be honest – why would you want to do that? Isn’t it more of a theoretical problem? Suppose a pipe breaks for some unknown reason, water will continue to flow and the concrete won’t dissolve or degrade because of that, right? I don’t fully understand this criticism.
5. Time savings
No criticism here, but a Swedish slab doesn’t require drying time, which speeds up the construction process and eliminates moisture in the house.
So far, I don’t see any significant negatives, though I am not an expert and can only judge based on the information I have. I would therefore appreciate an expert opinion. Are there any mistakes one can make when pouring a Swedish slab, and are there other disadvantages I might not have considered?
What would be the advantages of a conventional slab? I imagine it can also be insulated to achieve similar benefits in that respect. Then the main difference would be the drying time for the screed. Perhaps there are other considerations when building with calcium silicate bricks plus external insulation.
I look forward to your opinions.
Peter L
2eps+8PUR are worse than the standard structure of the Swedish panel (according to the website).
Yes, you can also install 30cm (12 inches) beneath the screed. But depending on the building regulations or planning permission, could this cause issues with the building height?
I just want to have an open discussion, not to preach or lecture. I just find it interesting.
Yes, you can also install 30cm (12 inches) beneath the screed. But depending on the building regulations or planning permission, could this cause issues with the building height?
I just want to have an open discussion, not to preach or lecture. I just find it interesting.
wrobel schrieb:
If you have concerns about the drinking water installation, you then place it in empty conduits. Thank you for your feedback! What exactly do you mean by your last sentence?
Alex85 schrieb:
I didn’t understand what you meant by mixing EPS and XPS. Although I didn’t find the exact passage when Googling, I think there is a misunderstanding here: it probably means that you cannot mix different types of rigid foam boards within the same layer of a surface—like mixing polystyrene and extruded polystyrene in one layer. However, using one type on one side of a complete element and the other type on the opposite side should be fine in terms of construction.
Alex85 schrieb:
You don’t need a kit from Jackodur for that. With these kinds of systems, I’m always unsure whether they are meant as a helpful time saver for professionals or if they rather allow contractors to delegate “proper” installation to unskilled helpers.
toxicmolotow schrieb:
For any other underfloor heating system embedded in screed, you could also say screed core activation, or for a bathroom wall heating system, lime sand brick, plaster, and tile core activation. *big like*
Peter L. schrieb:
I used the term because I believe that the Schwedenplatte and Futura follow this concept. You can call a tissue a “Tempo” or adhesive tape “Tesa.” I think, in this case, generic terms and brand names get mixed up in everyday language. Filigran ceiling is also a term popularly used for similar products from other manufacturers. The important thing is to understand what is meant. And here, I agree with Bieber0815 whether the product name just refers simply to a lowered floor heating system.
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T
Tom_Säuer6 Oct 2019 21:07Let me revisit this interesting thread.
To me, "thermal activation of the concrete core" means that the concrete is insulated on the underside so that heating energy from the underfloor heating system can be slowly absorbed and released from the concrete core above.
Instead of "activation," you could also say "charging." After all, nothing comes from nothing. The better the insulation underneath, the fewer heat losses there are.
Personally, I’m not comfortable with the thermal inertia of this system at all. Even at temperatures as low as -20°C (–4°F) in winter, a well-insulated and airtight wooden house in Germany should not cool down too quickly even without thermal activation of the concrete core. The combination of a thermal ground slab with integrated underfloor heating and heat pump has perhaps proven itself in Sweden, where winter temperatures can drop to -60°C (-76°F).
Over the past few years, I have given this subject a lot of thought. For a long time, the last-mentioned combination (underfloor heating with heat pump) in conjunction with solar thermal or photovoltaics with energy storage was my favorite. But then I calculated and realized that the only thing that can’t break down is what you don’t have. It also can’t wear out, age, or require maintenance.
My idea is a single-story wooden house (bungalow) built to passive house standards, with generous insulation both under and over the concrete slab, without underfloor heating; wood floors and wooden walls throughout. No tiles that can radiate cold…
Most of the required heat would come from solar gains through south-facing, large window areas, supplemented if necessary by mobile radiators/convector heaters and a wood stove for any situation. The only disadvantage I see is the increased effort needed for shading in the height of summer.
By the way, I plan to produce hot water decentralized via instantaneous water heaters directly at the four points of use (two bathrooms, kitchen, utility room). This eliminates the need for a hot water storage tank with heavy insulation.
Oh right, so I’ll be dependent on electricity... Who among you isn’t?
Regards,
Tom
To me, "thermal activation of the concrete core" means that the concrete is insulated on the underside so that heating energy from the underfloor heating system can be slowly absorbed and released from the concrete core above.
Instead of "activation," you could also say "charging." After all, nothing comes from nothing. The better the insulation underneath, the fewer heat losses there are.
Personally, I’m not comfortable with the thermal inertia of this system at all. Even at temperatures as low as -20°C (–4°F) in winter, a well-insulated and airtight wooden house in Germany should not cool down too quickly even without thermal activation of the concrete core. The combination of a thermal ground slab with integrated underfloor heating and heat pump has perhaps proven itself in Sweden, where winter temperatures can drop to -60°C (-76°F).
Over the past few years, I have given this subject a lot of thought. For a long time, the last-mentioned combination (underfloor heating with heat pump) in conjunction with solar thermal or photovoltaics with energy storage was my favorite. But then I calculated and realized that the only thing that can’t break down is what you don’t have. It also can’t wear out, age, or require maintenance.
My idea is a single-story wooden house (bungalow) built to passive house standards, with generous insulation both under and over the concrete slab, without underfloor heating; wood floors and wooden walls throughout. No tiles that can radiate cold…
Most of the required heat would come from solar gains through south-facing, large window areas, supplemented if necessary by mobile radiators/convector heaters and a wood stove for any situation. The only disadvantage I see is the increased effort needed for shading in the height of summer.
By the way, I plan to produce hot water decentralized via instantaneous water heaters directly at the four points of use (two bathrooms, kitchen, utility room). This eliminates the need for a hot water storage tank with heavy insulation.
Oh right, so I’ll be dependent on electricity... Who among you isn’t?
Regards,
Tom
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