Cellulose wadding, should we remove the rockwool?

[saint_rambert]

Hello everybody

I am about to redo the insulation of my lost roofs with cellulose wadding.

There remains a question on which I stumble: whether or not to remove the flocked rock wool which is currently in my roof space. Some craftsmen tell me yes, others tell me that it is not necessary because it is not in bad condition (just packed and therefore rather inoperative to date).

Thank you in advance for your clarification (we are still talking about a budget of around 400 € to remove the existing ...).

[Obamot]

Very difficult to decide on a building that one does not know, of which one has neither plan nor photo of the strategic places. So the tips below are to be taken with tweezers. This especially since in this forum, there must be several opinions on the issue among the pack pros.

Reason for keeping it
1) if it is packed, it would be very interesting (and imperative?) To fill with new material of identical type, to make it operative.
2) as much as possible do not remove it. A former chemist from the Battelle Institute told me that this type of material should be left "alone" because the release of dust would be very harmful (he referred to asbestos-type reactions).
3) By filling in the settlement, the coef of the two insulation will be added. Or there will be a need for less cellulose wadding to achieve the desired result.

Reason for removing it
Over-insulation. Determining if a house is "too insulated" or not "breathing" is a difficult task to grasp. It all depends on the dew point once the insulation is installed.
One thing is certain, the more you insulate, the more you need to take care of the ventilation of the habitat, even put an exchanger to heat the air that enters, by the humid air that has to come out.

Action to keep it
I would install a vapor barrier to avoid possible mold problems. I would plan from the start a "plan B" to install ventilation, if the first measurement is not enough (ie in case of dew point poorly suited to the construction).

[Woodcutter]

Hello everybody

I am about to redo the insulation of my lost roofs with cellulose wadding.

There remains a question on which I stumble: whether or not to remove the flocked rock wool which is currently in my roof space. Some craftsmen tell me yes, others tell me that it is not necessary because it is not in bad condition (just packed and therefore rather inoperative to date).

Thank you in advance for your clarification (we are still talking about a budget of around 400 € to remove the existing ...).

The LdR problem is not only linked to its state of conservation ...
The problem is to mix two insulators which do not react in the same way with respect to water vapor, which do not have the same properties at the acoustic level, which do not age the same, etc ...

For all these reasons, we NEVER put cotton wool on an existing LdV or LdR insulation.

Finally, if your LdR is packed and it does not come from mechanical compression, well it is in poor condition !
And the fibers it emits constantly are potentially very dangerous as mentioned above. But for this reason, I take it off!

[...]
Reason for removing it
Over-insulation. Determining if a house is "too insulated" or not "breathing" is a difficult task to grasp. It all depends on the dew point once the insulation is installed.
One thing is certain, the more you isolate, the more you need to treat the ventilation of the habitat, even put an exchanger to heat the air that enters, by the humid air that has to come out. [...]

You are confusing yet insulation and permeability to water vapor, it's a shame ...

A house is never "too isolated" (especially when we talk about roof spaces), that's a concept that is 50 years behind!

[Christophe]

Yes Obamot there is a gourance there!

And if Bucheron I know that you do not agree with me but the over-isolation exists.

It is putting more money (and CO2 incidentally) in its insulation than what this insulation, during its lifetime, will save !!

Not convinced? Let's take an extreme!

Do the calculation with R = 30 with a chemical wool which has 15 years of life ...

[Woodcutter]

[...] It is to put more money (and CO2 incidentally) in its insulation than what this insulation, during its lifetime, will save !!

Not convinced? Let's take an extreme!

Do the calculation with R = 30 with a chemical wool which has 15 years of life ...

Let's stay reasonable anyway ...

Your totally impossible example is not at all of the same order of idea as what Barraqu'Obamot was talking about ...

Indeed, I should perhaps have put a damper and talk about the homogeneity of the insulation in the home ... and specify that I do not use non-durable insulation !!!

[Obamot]

Yes indeed you are both right. An idea for a good book with formulas to update your knowledge ...?

Agree with the fact that it is better to remove it, taking into account your Lumberjack argument. And indeed it is a material whose harmfulness can grow with age. I would try to remember ...

On the other hand, over-insulation can exist in the case of renovation for old buildings, especially when they have been badly designed or badly transformed (I am trying to resolve a case at the moment). It remains to be seen whether we are talking about the same thing, I will tell you a little more tomorrow. Buenas noches.

[EVEN]

Hello

I am fitting out my attic and must carry out a reinforcement of joist
currently there is loose rock wool that I must remove (masks, gloves and glasses). After laying the load-bearing joists, I intend to replace this rock wool for sound insulation before placing the floor. What do you think?