Hello everyone,
In 2019, my wife and I purchased a semi-detached house built in 1925, which we completely renovated. Heating, plumbing, electrical system, flooring, new windows with double-glazed PVC frames, cavity wall insulation with hydrophobic loose-fill (Lammers insulation technology from Farven), roof insulation with 180mm (7 inches) Rockwool between rafters along with a Precit moisture-variable vapor retarder foil with an SD value of 0.2 to 50. External wall insulation of a 13 sqm (140 sq ft) extension with 100mm (4 inches) Neopor covered by a diffusion-open render. The roof of the extension is insulated with 200mm (8 inches) XPS (roof terrace) plus a polymer weldable membrane.
After two winters and two summers, the following recurring pattern emerges:
In winter, relative humidity ranges between 35% and 50%, depending on how many humidifiers we use.
In summer, the relative humidity rises to 50% to 80% in all rooms.
We regularly ventilate by cross-ventilation early in the morning and late in the evening throughout the entire house, but this has no significant effect. Currently, we use an electric dehumidifier, sometimes on the ground floor, sometimes on the upper floor, which extracts about 6 liters (6.3 quarts) of water from the air within 24 hours. This lowers the humidity to around 50% to 55%. However, this is not a permanent solution.
I would be very grateful for helpful, technically sound explanations regarding the cause and possible approaches to address this issue.
Best regards to all
Michael Dellas
In 2019, my wife and I purchased a semi-detached house built in 1925, which we completely renovated. Heating, plumbing, electrical system, flooring, new windows with double-glazed PVC frames, cavity wall insulation with hydrophobic loose-fill (Lammers insulation technology from Farven), roof insulation with 180mm (7 inches) Rockwool between rafters along with a Precit moisture-variable vapor retarder foil with an SD value of 0.2 to 50. External wall insulation of a 13 sqm (140 sq ft) extension with 100mm (4 inches) Neopor covered by a diffusion-open render. The roof of the extension is insulated with 200mm (8 inches) XPS (roof terrace) plus a polymer weldable membrane.
After two winters and two summers, the following recurring pattern emerges:
In winter, relative humidity ranges between 35% and 50%, depending on how many humidifiers we use.
In summer, the relative humidity rises to 50% to 80% in all rooms.
We regularly ventilate by cross-ventilation early in the morning and late in the evening throughout the entire house, but this has no significant effect. Currently, we use an electric dehumidifier, sometimes on the ground floor, sometimes on the upper floor, which extracts about 6 liters (6.3 quarts) of water from the air within 24 hours. This lowers the humidity to around 50% to 55%. However, this is not a permanent solution.
I would be very grateful for helpful, technically sound explanations regarding the cause and possible approaches to address this issue.
Best regards to all
Michael Dellas
We have had a dehumidifier running in the basement here for years (gypsum from the hardware store costs over 100€), the first one worked for 20 years. These devices usually have a built-in hygrostat switch. We set ours to 65%. The device only starts when the relative humidity rises above that and then consumes about 80W. In summer, the collection container can be half full after just one day.
In winter, it never runs, only if it is warm and humid outside and the basement air cools down, causing the relative humidity to increase.
There are typical misconceptions about gypsum: 50% relative humidity is not “half wet”!
If you reduce humidity below 30%, the construction timber will already start to crack.
60% is acceptable for comfort!
Systems with a compressor are sensible (they work like a refrigerator). There are also units based on the Peltier principle. These are cheaper, but their efficiency is too low (electricity costs!).
In winter, it never runs, only if it is warm and humid outside and the basement air cools down, causing the relative humidity to increase.
There are typical misconceptions about gypsum: 50% relative humidity is not “half wet”!
If you reduce humidity below 30%, the construction timber will already start to crack.
60% is acceptable for comfort!
Systems with a compressor are sensible (they work like a refrigerator). There are also units based on the Peltier principle. These are cheaper, but their efficiency is too low (electricity costs!).
Please
please what? (Five words and like that)
(Correct punctuation and such, better understanding and so)
konibar schrieb:
We have had a dehumidifier in the basement here for years (gypsum at the hardware store > 100€),
which, first of all, worked for 20 years.
These devices usually have a built-in hygrostat switch. We set it to 65%.
Only when the relative humidity rises above that does the device start and then consumes about 80W.
In summer, the collection container can sometimes be half full after just one day.
In winter, it never runs, only when it is humid and warm outside and
the basement air cools down, causing the relative humidity to rise.
But there are typical misunderstandings with gypsum:
50% relative humidity is not "half wet"!
If you dehumidify to below 30%, construction timber will already start to crack.
60% is acceptable for comfort!
Systems with a compressor are useful (they work like a refrigerator). There are also ones with the Peltier principle.
Those are cheaper, but their efficiency is too low (electricity costs!).
please what? (Five words and like that)
(Correct punctuation and such, better understanding and so)
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