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
H
Hutchinson12314 Jul 2021 13:51Currently, it is always between 65-75%. This is normal.
Windows are left open permanently.
The real problem usually occurs only in winter.
Windows are left open permanently.
The real problem usually occurs only in winter.
Hutchinson123 schrieb:
Currently always between 65-75%. That's normal.
Windows permanently open.
It's really only a problem in winter. Not only in winter. Especially on cooler basement/cellar walls, the humidity from the warm air can condense on the walls. Mold can develop there as well.
Hutchinson123 schrieb:
Window permanently open.Why is that? I don’t need a humid 28°C (82°F) inside the house.
H
Hutchinson12314 Jul 2021 15:46driver55 schrieb:
Why is that?
I don’t want a humid 28°C (82°F) inside the house. That’s just how I am.
As long as it’s not EXTREMELY hot, I keep the windows open.
I like fresh air and natural sounds, even if it gets warmer that way.
But I’m also located in northern Germany. It rarely gets really intense here.
Winniefred15 Jul 2021 07:02I also think this is normal. I don’t have a measuring device, but in our house from 1921, the basement is noticeably more humid in the summer than in the winter when you ventilate a lot (or rather, the door at the back is often left open because we are in the garden and usually enter through the basement). The reasons for this have already been explained. I did some reading on the topic, and everywhere it says that in summer you should only ventilate briefly and preferably not in the middle of the day. The humid air from outside simply brings even more moisture inside. I tried this method this summer and ventilated accordingly, and indeed the basement is now much drier than in previous years, which is also better for the house. The basement door now stays closed as much as possible.
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