I have an attic with flooring insulated with peat. The roof is mansard so there is no ventilated eaves, but there are two gable vents. The gables are insulated with about 8cm of fiberglass insulation. Should it be like that? Why insulate when it is still a cold attic?
Sincerely, Carl
Sincerely, Carl
No, there is no benefit to insulation there. Probably a previous owner saw it as an energy-saving measure. If you want to limit energy in the attic, you should add insulation to the floor structure. But if you do that, you need to check the house's ventilation. It's a bit complex to get into, but especially older houses with natural ventilation rely on, for example, the attic floor being leaky and not insulating the way we want today.
There is no disadvantage to having the gables insulated. If the temperature in the cold attic becomes too low, the risk of condensation increases. This risk is particularly high if the floor structure towards the floor below is well-insulated according to today's standards and/or the roof and gable peaks have a strong cooling effect due to material and compass orientation. Furthermore, the inside of the insulation should not have a vapor barrier if there is a risk that the attic temperature is lower than the outside temperature.
It seems reasonable that it shouldn't be colder than necessary in the attic if it is well-insulated downwards. Then the question is how much the gables contribute as a whole when the roof above is completely uninsulated.
Currently, it is insulated with fiberglass mats, and these should probably be replaced with a hygroscopic insulation to avoid moisture problems in that case.
Currently, it is insulated with fiberglass mats, and these should probably be replaced with a hygroscopic insulation to avoid moisture problems in that case.
It is partly about the points of the compass, partly about the roofing material. A roof with battens and clay tiles doesn't cool as much as a sheet metal roof.
Hygroscopic insulation is preferable as it allows any moisture on the facade panel to dry inward.
Hygroscopic insulation is preferable as it allows any moisture on the facade panel to dry inward.
It is absolutely not a bad solution from a technical perspective.D -Doozer- said:
It should not be insulated, the joist is what should have insulation. The gables above the joist should preferably be unsealed to ensure good ventilation in the attic. I should add that I am an amateur with a house from the 40s.
It is essentially correct that gables should be well ventilated. However, there are temperature situations where ventilation causes more harm than good. Hence my opinion to seal off the attic and install sorption dehumidifiers. They aren't even particularly expensive...
This was correct when the normal attic floor insulation was 15 cm of sawdust, and even for some time afterward. The heat leakage from below was significant. With today's insulation standards, attics can actually become too cold and ventilated.O Exsicco said:
I have exactly the same question so I'm posting it in the same thread.
I have a house built in the 90s with a metal roof and lightweight rot (membrane). The gables in the attic have about 20-25cm insulation of mineral wool. Some of the insulation has fallen down and I also need to remove it in other places to repair some holes in the facade.
So what is the function of insulation? Does the attic work better with or without insulation on the gables?
I have a house built in the 90s with a metal roof and lightweight rot (membrane). The gables in the attic have about 20-25cm insulation of mineral wool. Some of the insulation has fallen down and I also need to remove it in other places to repair some holes in the facade.
So what is the function of insulation? Does the attic work better with or without insulation on the gables?
If you have a house from the '90s, it is probably old enough to show how well the existing construction holds up over time. In other words, if the attic is okay currently, especially without mold, then the existing construction works acceptably. In such a case, nothing should be changed.
The principle is as Justus wrote.
Getting a cold attic to function over time, without mold, is like walking a tightrope. According to Fukthandboken, that is Sweden's leading professors and moisture experts, there is currently no way to build a moisture-safe cold attic (without active components). Today's insulation/energy requirements make attics too cold/damp. Therefore, the advice is always not to change a proven functioning construction.
The principle is as Justus wrote.
Getting a cold attic to function over time, without mold, is like walking a tightrope. According to Fukthandboken, that is Sweden's leading professors and moisture experts, there is currently no way to build a moisture-safe cold attic (without active components). Today's insulation/energy requirements make attics too cold/damp. Therefore, the advice is always not to change a proven functioning construction.
I have the same question now and it's difficult to get a straight answer, people say different things there 😆. I had moisture in the attic and got a safety guard installed with a fan + heating cable, as well as sealed (as best as possible) a passage between the walls where ventilation and sewer venting go through the attic.
Initially, the gables were insulated but this insulation had fallen down..., I think it can't be wrong to have insulation at least as it might possibly help to raise the temperature in the attic, even if only a little, it is probably based on the principle that the heating cable works with the safety guard, warmer air holds more moisture. As previously written, there is no Safe solution, but I'm thinking if there are better/worse measures... 👀
Initially, the gables were insulated but this insulation had fallen down..., I think it can't be wrong to have insulation at least as it might possibly help to raise the temperature in the attic, even if only a little, it is probably based on the principle that the heating cable works with the safety guard, warmer air holds more moisture. As previously written, there is no Safe solution, but I'm thinking if there are better/worse measures... 👀
It may well be justified to insulate the gables since a heating cable is based on raising the temperature, thereby lowering the RH. If insulation would worsen the situation, then it would just be a matter of installing a gable vent or two. Preferably with active regulation based on both indoor attic temperature and outdoor temperature as well as RH.