The house has an upper floor that is a cold attic with a lot of natural ventilation. On the upper floor, there is a separate room that had 15 cm of sawdust as insulation in the ceiling. I removed the sawdust and the plan is to lay cellulose. From this flat surface, there is still a space of 80 cm up to the ridge with natural ventilation. My question is whether I need to install a vapor barrier here? There has never been a vapor barrier before, and the room has stood for many decades.
For what reason did you want to remove the sawdust?
Changing structures of this kind of house always comes with a certain risk, as it often results in a new moisture balance. In general, the most important thing to consider is that you should preferably get rid of the moisture in ways other than having it pass through wall or roof structures. Ideally, ensure that you have control over the moisture introduced, and preferably keep this introduction low.
Therefore, you should consider what sources of moisture might exist (a person exhales a liter per day, clothes drying, cooking, showering contribute far more), and moisture may also come through the flooring from the floor below, for example. Then consider what kind of ventilation you should have to handle this.
A vapor barrier or vapor retarder is rarely wrong, but there should be other paths for moisture to escape the house, meaning ventilation, in practice.
I know this has been a somewhat vague answer, but there is no honest and certain answer, no silver bullet that is a guaranteed "solution."
Changing structures of this kind of house always comes with a certain risk, as it often results in a new moisture balance. In general, the most important thing to consider is that you should preferably get rid of the moisture in ways other than having it pass through wall or roof structures. Ideally, ensure that you have control over the moisture introduced, and preferably keep this introduction low.
Therefore, you should consider what sources of moisture might exist (a person exhales a liter per day, clothes drying, cooking, showering contribute far more), and moisture may also come through the flooring from the floor below, for example. Then consider what kind of ventilation you should have to handle this.
A vapor barrier or vapor retarder is rarely wrong, but there should be other paths for moisture to escape the house, meaning ventilation, in practice.
I know this has been a somewhat vague answer, but there is no honest and certain answer, no silver bullet that is a guaranteed "solution."
Well, you might want to increase the insulation a bit, get slightly lower electricity bills.
That is, add a bit thicker insulation now.
That is, add a bit thicker insulation now.
In order for us to move forward on the issue, we probably need to get a little more information.
Since you had sawdust, I guess it's an older house.
Is this room kind of built like a house within the cold attic?
What is the room used for, and how warm should it be?
And by the way, welcome to the forum!
Since you had sawdust, I guess it's an older house.
Is this room kind of built like a house within the cold attic?
What is the room used for, and how warm should it be?
And by the way, welcome to the forum!
Yes, that is also a justified question.
Personally, I am of the opinion that much of what is sold as ecofiber, vapor barriers, etc., is somewhat of marketing fluff, essentially bs.
They try to create the impression that the products magically create a healthy house, protect the house against moisture, mold, rot.
But a fundamentally flawed construction can never be fixed with some miracle materials.
And a fundamentally functioning construction, in the form of never showering indoors and having very poor insulation and heating a lot consistently, then becomes a flawed construction when you tweak all the parameters, i.e., start showering indoors, add insulation and start saving on energy.
Yes, I mean for old houses that have lasted for a century, but then suddenly have problems.
Personally, I am of the opinion that much of what is sold as ecofiber, vapor barriers, etc., is somewhat of marketing fluff, essentially bs.
They try to create the impression that the products magically create a healthy house, protect the house against moisture, mold, rot.
But a fundamentally flawed construction can never be fixed with some miracle materials.
And a fundamentally functioning construction, in the form of never showering indoors and having very poor insulation and heating a lot consistently, then becomes a flawed construction when you tweak all the parameters, i.e., start showering indoors, add insulation and start saving on energy.
Yes, I mean for old houses that have lasted for a century, but then suddenly have problems.
The house is from around the 1800s, and this room is a separate part of the cold attic with walls made of timber, planks, and sawdust. I haven't checked the details of how the walls are constructed yet. The house itself is heated by fireplaces, the natural draft from the floor, etc., remains, and I haven't added any insulation yet. The change made when I moved in was a shower with a water heater. Everything looks dry and fine. The room is used as an office, and the plan is to use a fireplace or a heater to warm the room during the periods it needs to be used.