ᐅ Cement screed with underfloor heating not drying any further?!
Created on: 14 Dec 2017 09:00
C
Cara-SolHello,
I am a client from Schleswig-Holstein and absolutely desperate.
Apart from having very little knowledge about screed, I want to reach out to you with my problem:
Since summer, we have been building a small detached house (135 sqm (1453 sq ft), solid construction).
On October 17, 2017, our cement screed was installed (6 cm (2.4 inches) thick). We have underfloor heating throughout the house.
After 2 days, we were allowed to walk on the screed, and after one week, we started ventilating (opening windows fully for 10 minutes every morning and evening).
Since November 15, 2017, the underfloor heating’s drying program has been running, and every time we ventilate, we wipe the moisture from the windows, concrete ceiling, and doors with towels.
Since November 16, 2017, a large construction dryer has been running, and since November 23, a second smaller construction dryer (one on the lower floor, one on the upper floor).
On December 4, 2017, residual moisture in the screed was measured at 2.8% (unfortunately only in one spot). This was a CM measurement. After that, we started painting and plastering the walls (which may have introduced moisture again?).
On December 11, 2017, measurements were taken again, using the same method in several rooms on both floors, showing varying values between 2.7% and 3%.
We are so desperate! We have to leave our apartment by the end of December, and we have already had to postpone kitchen and staircase installation until early January. This means we will probably move in on December 31, 2017, without a staircase, kitchen, or flooring.
On the upper floor, carpet will be installed (with adhesive/fixation), and downstairs vinyl flooring (with leveling compound/adhesive), which we will do ourselves.
But we will never reach 1.8%!!! Many say it should have been dry by now... The screed installer told us this is strange and advised us to close everything for three days soon, keep the construction dryers and heating on, and not enter the house.
Could the screed have suffered a so-called “capillary break”? We are very afraid of this!
What have you done, how did you dry it, and what were your moisture measurements?
I would be grateful for any small help or advice!
Best regards,
Cara
I am a client from Schleswig-Holstein and absolutely desperate.
Apart from having very little knowledge about screed, I want to reach out to you with my problem:
Since summer, we have been building a small detached house (135 sqm (1453 sq ft), solid construction).
On October 17, 2017, our cement screed was installed (6 cm (2.4 inches) thick). We have underfloor heating throughout the house.
After 2 days, we were allowed to walk on the screed, and after one week, we started ventilating (opening windows fully for 10 minutes every morning and evening).
Since November 15, 2017, the underfloor heating’s drying program has been running, and every time we ventilate, we wipe the moisture from the windows, concrete ceiling, and doors with towels.
Since November 16, 2017, a large construction dryer has been running, and since November 23, a second smaller construction dryer (one on the lower floor, one on the upper floor).
On December 4, 2017, residual moisture in the screed was measured at 2.8% (unfortunately only in one spot). This was a CM measurement. After that, we started painting and plastering the walls (which may have introduced moisture again?).
On December 11, 2017, measurements were taken again, using the same method in several rooms on both floors, showing varying values between 2.7% and 3%.
We are so desperate! We have to leave our apartment by the end of December, and we have already had to postpone kitchen and staircase installation until early January. This means we will probably move in on December 31, 2017, without a staircase, kitchen, or flooring.
On the upper floor, carpet will be installed (with adhesive/fixation), and downstairs vinyl flooring (with leveling compound/adhesive), which we will do ourselves.
But we will never reach 1.8%!!! Many say it should have been dry by now... The screed installer told us this is strange and advised us to close everything for three days soon, keep the construction dryers and heating on, and not enter the house.
Could the screed have suffered a so-called “capillary break”? We are very afraid of this!
What have you done, how did you dry it, and what were your moisture measurements?
I would be grateful for any small help or advice!
Best regards,
Cara
N
nightdancer14 Dec 2017 09:28Dehumidifiers only help if there is one placed in every room. During this time, plastering and painting are definitely not possible.
Hello,
for me, it took about 6 weeks until the screed reached 2% moisture. The only thing that really helps is ventilation, ventilation, ventilation. Regular construction dryers just don’t remove enough moisture from the house. I placed humidity meters in every room and whenever the indoor humidity rose above 60%, I opened the windows. After airing out, the humidity briefly dropped to around 40%. That way, you can actually see the drying progress.
You can only get rid of the moisture if the air is nice and dry. And right now, conditions are perfect since it’s cold outside.
for me, it took about 6 weeks until the screed reached 2% moisture. The only thing that really helps is ventilation, ventilation, ventilation. Regular construction dryers just don’t remove enough moisture from the house. I placed humidity meters in every room and whenever the indoor humidity rose above 60%, I opened the windows. After airing out, the humidity briefly dropped to around 40%. That way, you can actually see the drying progress.
You can only get rid of the moisture if the air is nice and dry. And right now, conditions are perfect since it’s cold outside.
C
chand198614 Dec 2017 17:48I see it the same way as Nordlys. It’s probably due to the weather. The extended duration now simply clashes with your very tight schedule.
There’s really not much help for you here. Just reassure yourselves that it will get better.
Is it possible to use a temporary room and store the furniture for a month?
Moving in and then partially moving out again for follow-up work is very inconvenient.
There’s really not much help for you here. Just reassure yourselves that it will get better.
Is it possible to use a temporary room and store the furniture for a month?
Moving in and then partially moving out again for follow-up work is very inconvenient.
Hello,
as long as the temperature outside is <= 5°C (41°F) and inside it is 20°C (68°F), rain is not a problem. That’s why it’s called relative humidity. If I take 5°C (41°F) cold air and assume it has 100% humidity, the same air at 20°C (68°F) will only have about 40% relative humidity. This is because warmer air can hold more water vapor.
Air at 5°C (41°F) holds a maximum of 6.9 g/m³ of water = 100%, while air at 20°C (68°F) can hold 17.3 g/m³ = 100%. So if I bring cold air into the house (even if it is raining, it can’t be more than 100%), I actually dry out the house.
A simple calculation: a room measuring 25 m² (269 ft²) has a volume of 62 m³ (2,190 ft³). At 20°C (68°F) and 100% relative humidity, that is about 1 liter (34 fl oz) of water in the air. If I completely replace the air once with 5°C (41°F) cold air at 100% humidity, then there is only about 0.43 liter (15 fl oz) of water left in the air. If I then warm this air up to 20°C (68°F) using geothermal heat, it can absorb another half liter (17 fl oz) of water from the surroundings such as walls and floor.
That’s why it is important to ventilate, even when it’s raining, as long as the outside air is colder than inside. In summer, it is much worse because the effect is reversed.
Many people get this wrong. I have this discussion every year with my tenants. They think they should ventilate the basement in summer and wonder why it becomes damp.
Even better is when it’s freezing outside, below 0°C (32°F). Then the effect is even stronger.
This is also how a construction dryer works. It’s basically a reversed refrigerator. It has a cooling plate over which warm air is blown. Cooling the air reduces its capacity to hold water vapor, so water condenses on the plate and drips into a container. Then the air is warmed again and can absorb moisture once more, and so on.
But cold outdoor air has the advantage that you get it for free and don’t need to cool it down first with a construction dryer.
So ventilate, ventilate, ventilate...
as long as the temperature outside is <= 5°C (41°F) and inside it is 20°C (68°F), rain is not a problem. That’s why it’s called relative humidity. If I take 5°C (41°F) cold air and assume it has 100% humidity, the same air at 20°C (68°F) will only have about 40% relative humidity. This is because warmer air can hold more water vapor.
Air at 5°C (41°F) holds a maximum of 6.9 g/m³ of water = 100%, while air at 20°C (68°F) can hold 17.3 g/m³ = 100%. So if I bring cold air into the house (even if it is raining, it can’t be more than 100%), I actually dry out the house.
A simple calculation: a room measuring 25 m² (269 ft²) has a volume of 62 m³ (2,190 ft³). At 20°C (68°F) and 100% relative humidity, that is about 1 liter (34 fl oz) of water in the air. If I completely replace the air once with 5°C (41°F) cold air at 100% humidity, then there is only about 0.43 liter (15 fl oz) of water left in the air. If I then warm this air up to 20°C (68°F) using geothermal heat, it can absorb another half liter (17 fl oz) of water from the surroundings such as walls and floor.
That’s why it is important to ventilate, even when it’s raining, as long as the outside air is colder than inside. In summer, it is much worse because the effect is reversed.
Many people get this wrong. I have this discussion every year with my tenants. They think they should ventilate the basement in summer and wonder why it becomes damp.
Even better is when it’s freezing outside, below 0°C (32°F). Then the effect is even stronger.
This is also how a construction dryer works. It’s basically a reversed refrigerator. It has a cooling plate over which warm air is blown. Cooling the air reduces its capacity to hold water vapor, so water condenses on the plate and drips into a container. Then the air is warmed again and can absorb moisture once more, and so on.
But cold outdoor air has the advantage that you get it for free and don’t need to cool it down first with a construction dryer.
So ventilate, ventilate, ventilate...
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