ᐅ Proper Ventilation and Drying of Interior Plaster / Drying Time
Created on: 10 Sep 2016 20:25
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Hausi2016
Hello everyone,
are there any physicists or experts familiar with physics here?
I have questions regarding the drying of interior plaster.
In our new build, the interior plaster was completed the day before yesterday, and we are now considering how to remove the moisture from the house or walls as effectively as possible without causing damage, especially in the basement. The basement was also underwater by about 25 cm (10 inches) roughly two months ago. (Our house is built on a slope, so the basement is half underground, and the other half extends above the ground level by about half its height. On the basement side, there are four standard windows above ground level.)
According to various guides, some construction workers, and a drying company, in summer you should only ventilate at night when it’s at least 5°C (9°F) cooler outside than inside, and NEVER during the hot daytime hours. This makes sense from a scientific standpoint based on the water vapor saturation curve. Now, our question is: does this advice apply only to finished houses, or also to fresh interior plaster to help it dry quickly and effectively? We have read in other forums that, after plastering, continuous ventilation during the day is recommended, and that it should not be ventilated at night.
We want to avoid any mistakes in the basement in particular, to prevent mold growth!
Currently, inside the house during the day, we have about 82% relative humidity at 22–23°C (72–73°F). In the basement, it’s about 90% relative humidity at 18–19°C (64–66°F).
When we ventilate at night, the temperature drops to approximately 17–18°C (63–64°F) with about 70% relative humidity.
Another question is: how long should we wait after plastering before installing the floor insulation? Could any remaining moisture from the plastered wall migrate into the insulation and cause damage?
Thank you very much in advance for your answers!
Best regards,
hausi2016
are there any physicists or experts familiar with physics here?
I have questions regarding the drying of interior plaster.
In our new build, the interior plaster was completed the day before yesterday, and we are now considering how to remove the moisture from the house or walls as effectively as possible without causing damage, especially in the basement. The basement was also underwater by about 25 cm (10 inches) roughly two months ago. (Our house is built on a slope, so the basement is half underground, and the other half extends above the ground level by about half its height. On the basement side, there are four standard windows above ground level.)
According to various guides, some construction workers, and a drying company, in summer you should only ventilate at night when it’s at least 5°C (9°F) cooler outside than inside, and NEVER during the hot daytime hours. This makes sense from a scientific standpoint based on the water vapor saturation curve. Now, our question is: does this advice apply only to finished houses, or also to fresh interior plaster to help it dry quickly and effectively? We have read in other forums that, after plastering, continuous ventilation during the day is recommended, and that it should not be ventilated at night.
We want to avoid any mistakes in the basement in particular, to prevent mold growth!
Currently, inside the house during the day, we have about 82% relative humidity at 22–23°C (72–73°F). In the basement, it’s about 90% relative humidity at 18–19°C (64–66°F).
When we ventilate at night, the temperature drops to approximately 17–18°C (63–64°F) with about 70% relative humidity.
Another question is: how long should we wait after plastering before installing the floor insulation? Could any remaining moisture from the plastered wall migrate into the insulation and cause damage?
Thank you very much in advance for your answers!
Best regards,
hausi2016
H
Hausi201611 Sep 2016 07:06The screed insulation, meaning the polystyrene boards installed beneath the underfloor heating and the screed.
For interior plaster, airing out the room by opening windows briefly several times a day is usually sufficient. Constantly leaving windows open can cause drafts, which leads to some areas drying faster while others, especially corners shielded from the airflow, remain damp. This can result in cracking.
Although the interior plaster is on average only about 1 cm (0.4 inches) thick, the large surface area causes high humidity. The masonry reduces the moisture release.
Be careful with "technical ventilation." Using a dehumidifier is recommended. However, heating fans or gas heaters are not advisable. Burning gas produces moisture, and a high-powered fan can push this moisture deeper into the walls, causing uneven moisture distribution and possibly leading to cracks.
Do you have only the bituminous waterproof membrane between the concrete slab and the first course of blocks, or is there also a masonry barrier between the first and second course?
If you have spoken with a building drying company, what does the specialist say about flooding to a depth of 25 cm (10 inches)?
Although the interior plaster is on average only about 1 cm (0.4 inches) thick, the large surface area causes high humidity. The masonry reduces the moisture release.
Be careful with "technical ventilation." Using a dehumidifier is recommended. However, heating fans or gas heaters are not advisable. Burning gas produces moisture, and a high-powered fan can push this moisture deeper into the walls, causing uneven moisture distribution and possibly leading to cracks.
Do you have only the bituminous waterproof membrane between the concrete slab and the first course of blocks, or is there also a masonry barrier between the first and second course?
If you have spoken with a building drying company, what does the specialist say about flooding to a depth of 25 cm (10 inches)?
N
nordbayer14 May 2020 19:37I’ll join this old thread. When drying interior plaster, would it be helpful to tilt open one window at the bottom and one at the top of the house and then set up a small heater with 1-2 kW? Could this cause any damage to the lime gypsum plaster? Apart from the fact that such a small heater might have only a very mild effect.
Vicky Pedia15 May 2020 15:26Insulation can be installed, and as mentioned here, it’s recommended to ventilate the rooms by fully airing them out three times a day. The moisture in the plaster is not from the water used for mixing; it is the result of the chemical reaction, which is complete after 28 days. After that, it starts to dry. By the way, wiping any droplets off the window frames regularly with an absorbent cloth also helps. Every half cup of water counts. Technically, drying only occurs after 4 weeks, otherwise there is a risk of cracks.
bauenmk202015 May 2020 16:54I am currently having very good experiences with window vacuums for cleaning windows and water bead spots on walls (plaster).
It is important to allow the plaster/screed enough time to cure. The water that remains should then be removed through air exchange and by vacuuming/wiping it away to the outside.
It is important to allow the plaster/screed enough time to cure. The water that remains should then be removed through air exchange and by vacuuming/wiping it away to the outside.
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