Hello everyone,
I wanted to ask for your ideas or experiences with the following unusual issue.
In our newly built single-family home, we installed a Dolle attic ladder to an unheated pitched attic space. During the heating season, I noticed moisture collecting on the sides of the hatch cover. I thought, aha – cold and warm air are meeting – a leak. I reported this directly to the carpenter, who checked the seals on the frame; everything was fine. However, on the hatch cover itself, he noticed it was warped. It was bowed upward in the middle and downward toward the corners – like a banana. Not extremely obvious visually, but you can see it if you look from the right angle and follow the edges.
So the hatch cover was replaced with a new one. A few days later, the same phenomenon occurred, with the cover warping the same way. The carpenter was puzzled; they hadn’t encountered this problem before. An inquiry was made to Dolle and it is still unresolved.
Meanwhile, the old cover, which is stored at the carpenter’s workshop, has warped back and is now straight again.
Has anyone else experienced this problem? Do you have any ideas about what might be causing it?
I wanted to ask for your ideas or experiences with the following unusual issue.
In our newly built single-family home, we installed a Dolle attic ladder to an unheated pitched attic space. During the heating season, I noticed moisture collecting on the sides of the hatch cover. I thought, aha – cold and warm air are meeting – a leak. I reported this directly to the carpenter, who checked the seals on the frame; everything was fine. However, on the hatch cover itself, he noticed it was warped. It was bowed upward in the middle and downward toward the corners – like a banana. Not extremely obvious visually, but you can see it if you look from the right angle and follow the edges.
So the hatch cover was replaced with a new one. A few days later, the same phenomenon occurred, with the cover warping the same way. The carpenter was puzzled; they hadn’t encountered this problem before. An inquiry was made to Dolle and it is still unresolved.
Meanwhile, the old cover, which is stored at the carpenter’s workshop, has warped back and is now straight again.
Has anyone else experienced this problem? Do you have any ideas about what might be causing it?
A
Allthewayup21 Feb 2024 20:25Which type of attic ladder is installed? Is the insulation placed on the concrete ceiling within the cold roof space? We also have an attic ladder leading into the cold roof, and it’s important to be aware that it breaks the building’s thermal envelope, so the ladder should have an appropriate U-value. Ours has a double perimeter seal and an insulated cover (about 10-12cm (4-5 inches), I would estimate). Condensation hasn’t been an issue so far.
A
Allthewayup21 Feb 2024 20:34WilderSueden schrieb:
How do you know it isn’t the case? Most attics are dimly lit, so it’s easy to miss. And you don’t go up there very often. As long as it’s just a little moisture, you don’t notice it that much…
…Basically, I would say the hatch has to be able to handle that. Its intended use is to separate the warm, humid indoor air from the cold, dry attic air. Here, we’re talking about absolute humidity. The attic typically has a relative humidity of over 70%. No surprise, since it roughly follows the outside air (the attic isn’t completely airtight), which can easily be above 90% in damp, cold weather. That’s exactly the issue with this setup. Many people open the attic access hatch in winter to get or store Christmas decorations, etc., repeatedly letting warm air flow into the cold roof space. This air then cools down there, causing condensation.
I recommend placing an adsorption dehumidifier up there with a built-in timer or connected to a timer switch and running it for 2-3 hours after leaving the attic. We have already implemented this and reduce humidity from 70-72% down to 62-64%. The cold roof space is sealed tightly enough to develop mold if you don’t keep an eye on it. We only observe actual air exchange during storms because the dry ridge vent and gaps between the wood fiber boards allow air movement then.
In modern, fairly airtight new builds, the cold roof space is technically not intended as living space, but many of us—including ourselves—wish otherwise, since space ultimately equals money. That’s why appropriate countermeasures are even more important. You don’t have this problem in summer.
W
WilderSueden21 Feb 2024 21:30There is usually more than one issue. The open hatch is certainly one of them, although I have not been able to confirm that it affects the humidity in the attic more than the weather does. Another problem is that any leakage around the hatch also causes condensation. For me, the problem is less the hatch’s gasket itself and more the installation of the frame in the ceiling. This has been corrected twice already, and I’m still not completely sure if it is fully sealed now.
Ideally, a cold roof is designed either with small windows on the gable side or with ventilation elements. A dehumidifier is also an option, but then the issue becomes managing the condensate.
Ideally, a cold roof is designed either with small windows on the gable side or with ventilation elements. A dehumidifier is also an option, but then the issue becomes managing the condensate.
Allthewayup schrieb:
Which pull-down attic ladder is actually installed? Is the insulation placed on the concrete ceiling inside the cold roof space? We also have an attic ladder leading into the cold roof, and it’s important to keep in mind that this breaks the building’s thermal envelope, so you should pay attention to the ladder’s U-value. Ours has a double continuous seal and an insulated lid (I’d estimate about 10–12cm (4–5 inches)). Condensation has not been an issue so far. From the upper floor to the loft, we have drywall, and above that, insulation with mineral wool WLG 035. On the loft floor, there are OSB boards again, so it is fully walkable (except for the edges and the section where the side gable of the house is located). The ladder should be a Dolle Click Fix measuring 120x70.
Allthewayup schrieb:
That’s exactly the problem with this type of setup. Many people open the attic hatch in winter to get Christmas decorations or other items and then close it again, repeatedly allowing warm air to enter the cold roof space. The air cools down there, leading to condensation.
I recommend placing an adsorption dryer up there with a built-in timer or connected to a timer switch and running it for 2–3 hours after leaving the attic. I’ll keep the dryer suggestion in mind, thanks!
WilderSueden schrieb:
For me, the problem isn’t so much the hatch’s seal itself but rather how the frame is installed in the ceiling. It has already been corrected twice, and I’m still not fully sure whether it’s completely airtight now. The carpenter checked the frame first and said everything was done correctly and the seal was fine as well.
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