We realized after 12 days that our installer had set the wrong drying program. It has been running constantly at 30 degrees Celsius (86°F) for 12 days. This is an electrically powered external device, not the heat pump.
The installer is coming tomorrow. What do you recommend? I will have the screed moisture measured today. However, my main concern is the expansion. If I increase the temperature from 30 to 40 degrees Celsius (86 to 104°F) tomorrow, then from Friday to Saturday to 50 degrees Celsius (122°F), and keep it there for two days until Monday, will that be sufficient?
We have already scheduled all subsequent work steps with all contractors after the drying program. It would be a disaster if we had to extend the program.
The installer is coming tomorrow. What do you recommend? I will have the screed moisture measured today. However, my main concern is the expansion. If I increase the temperature from 30 to 40 degrees Celsius (86 to 104°F) tomorrow, then from Friday to Saturday to 50 degrees Celsius (122°F), and keep it there for two days until Monday, will that be sufficient?
We have already scheduled all subsequent work steps with all contractors after the drying program. It would be a disaster if we had to extend the program.
W
Wintersonne3 May 2020 16:16Why avoid drafts? Is it because the surface dries faster while it remains damp underneath? Or does drafts cause cracks?
With CAF, you are supposed to ventilate at the latest after the third day, if I understand correctly.
With CAF, you are supposed to ventilate at the latest after the third day, if I understand correctly.
bauenmk20203 May 2020 16:16Okay, thanks! No, drafts do not occur because all windows are on the east and north walls and the rooms are not connected.
@bauenmk2020. I would strongly recommend using dehumidifiers. I tried to save money by not renting one for my screed, but I deeply regretted it! Once the functional heating started, I had to ventilate at least every hour to keep the moisture under control. I have wood-aluminum windows installed, which didn’t make things any easier.
By the way, the heating program with the electric heater cost me about 1000 euros in electricity, plus the drying heat required before laying the floor covering.
By the way, the heating program with the electric heater cost me about 1000 euros in electricity, plus the drying heat required before laying the floor covering.
"Why no drafts? Because the surface dries faster while underneath it remains damp? Or do drafts cause cracks?"
Answer @ "Wintersonne":
Exactly! Besides crack formation, two other negative effects can be expected:
1. The screed (cement, CA + CAF) loses the water it needs too early for the chemical reaction on the surface (resulting in insufficient hardness), and
2. Cement screeds then tend to deform.
-----------------
"With CAF, one should ventilate at the latest after the third day, if I understood correctly."
Answer:
That is only partially correct. You CAN start cross-ventilating with CAF after the third day—but you don’t have to!
----------------
The advice from "rastlos" is also not a mandatory measure but involves certain risks.
Anyone trying to save money through forced drying methods (condensation drying machines) has fundamentally misunderstood the purpose!
Forced drying methods are intended to accelerate the readiness for covering of a screed that has already sufficiently hardened, which either has a very thick layer or is a poorly drying CAF with a very dense structure.
In new buildings, however, moisture comes not only from the screed but also from the wall plaster and masonry.
Here, intensive ventilation after the 21st day is usually completely sufficient.
Electricity costs for forced drying are actually significant.
If you calculate over a longer period, for example over 3 years, the use of a forced drying device can indeed pay off.
This is because the dwelling no longer has to be “lived in damp,” which in winter always means higher heating costs (humid indoor air with the same temperature inevitably contains more energy than dry indoor air).
So please don’t compare “apples and oranges,” but consider the overall picture. Certainly not easy for a layperson, admittedly!
Best regards: KlaRa
Answer @ "Wintersonne":
Exactly! Besides crack formation, two other negative effects can be expected:
1. The screed (cement, CA + CAF) loses the water it needs too early for the chemical reaction on the surface (resulting in insufficient hardness), and
2. Cement screeds then tend to deform.
-----------------
"With CAF, one should ventilate at the latest after the third day, if I understood correctly."
Answer:
That is only partially correct. You CAN start cross-ventilating with CAF after the third day—but you don’t have to!
----------------
The advice from "rastlos" is also not a mandatory measure but involves certain risks.
Anyone trying to save money through forced drying methods (condensation drying machines) has fundamentally misunderstood the purpose!
Forced drying methods are intended to accelerate the readiness for covering of a screed that has already sufficiently hardened, which either has a very thick layer or is a poorly drying CAF with a very dense structure.
In new buildings, however, moisture comes not only from the screed but also from the wall plaster and masonry.
Here, intensive ventilation after the 21st day is usually completely sufficient.
Electricity costs for forced drying are actually significant.
If you calculate over a longer period, for example over 3 years, the use of a forced drying device can indeed pay off.
This is because the dwelling no longer has to be “lived in damp,” which in winter always means higher heating costs (humid indoor air with the same temperature inevitably contains more energy than dry indoor air).
So please don’t compare “apples and oranges,” but consider the overall picture. Certainly not easy for a layperson, admittedly!
Best regards: KlaRa
The suggestion about using dehumidifiers was not intended to save money. Of course, running dehumidifiers adds a significant amount to the electricity bill.
My main issue was that despite ventilating every hour, I was unable to remove enough moisture from inside. Without using the dehumidifiers, I would likely have had serious mold problems. The wood-aluminum windows also cannot withstand such high humidity over time.
However, my screed had enough time to cure properly before the heating was turned on. Unfortunately, the heating unit was still in use at another construction site and only arrived late at mine. I suspect this is why my screed does not have any curling issues at all. At a known site, heating began after just seven days. They are now facing severe curling of their screed. They also did not use any dehumidifiers during that period and now have mold on their exposed roof trusses and in some areas of the plaster—despite frequent ventilation.
It is also very important that the insulation in the attic structure is already installed and sealed to be 100% airtight against vapor. Otherwise, all the moisture migrates into the attic. It takes quite a while for the attic to dry sufficiently... If this is overlooked and insulation along with a vapor barrier is installed in a damp attic, one will likely be surprised after a few years to find that all the beams are covered in black mold. The attic hatch should also be sealed to be 100% vapor-tight.
My main issue was that despite ventilating every hour, I was unable to remove enough moisture from inside. Without using the dehumidifiers, I would likely have had serious mold problems. The wood-aluminum windows also cannot withstand such high humidity over time.
However, my screed had enough time to cure properly before the heating was turned on. Unfortunately, the heating unit was still in use at another construction site and only arrived late at mine. I suspect this is why my screed does not have any curling issues at all. At a known site, heating began after just seven days. They are now facing severe curling of their screed. They also did not use any dehumidifiers during that period and now have mold on their exposed roof trusses and in some areas of the plaster—despite frequent ventilation.
It is also very important that the insulation in the attic structure is already installed and sealed to be 100% airtight against vapor. Otherwise, all the moisture migrates into the attic. It takes quite a while for the attic to dry sufficiently... If this is overlooked and insulation along with a vapor barrier is installed in a damp attic, one will likely be surprised after a few years to find that all the beams are covered in black mold. The attic hatch should also be sealed to be 100% vapor-tight.
bauenmk20203 May 2020 22:59@rastlos
In our case, the upper floor ceiling is sealed with a vapor barrier. There isn't even a floor hatch installed yet.
Did you wipe the condensation away with a cloth or use a window vacuum?
In our case, the upper floor ceiling is sealed with a vapor barrier. There isn't even a floor hatch installed yet.
Did you wipe the condensation away with a cloth or use a window vacuum?
Similar topics