Insulation with brick in the ceiling of converted attics

[jieff]

I recently purchased an 1971 pavilion with attic space and a ceiling made of 3 cm bricks and an 1 cm plaster finish. The roof of mechanical tiles is insulated by an air gap of more than 5 cm, 5 to 7 cm of glass wool directly placed on the brick.
The current insulation is insufficient and I do not know how to complete it. the best could be to decant or blow the existing ceiling but the heaviness of the site scares me.
For winter comfort, I was planning to supplement with 16 cm of insulation under plaster (16 cm available between the purlins .It seems that I have to reach 20 cm of mineral wool at least, but should I consider the existing thickness ?
For summer comfort, is it interesting to keep the ceiling of brick and plaster for its interesting inertia in thermal phase shift ???? Does it lose interest if the insulation is completed below?
What insulator to take from this case: is wood fiber really more interesting than mineral wool or is it negligible if it is associated with a brick ceiling and plaster? In this case is rock wool superior to glass wool for thermal phase shift?
Finally the house is located on a passage of planes, what would be the ideal insulation in complement?

Many thanks for each of your answers or suggestions.

[elephant]

I have trouble figuring your 3 bricks cm ceiling attic.
First of all, what space (thickness of the beams) do you have?
A sketch would be nice.

[jieff]

Here is a small diagram, with a slope of 45 °:

================= Mechanical tile
7 cm blade air
//////////////////////////////// glass wool 5-7 cm
UUUUUUUU battens
= | | ===== | | ==== | | === platrire ceiling bricks on hook 3cm + plaster 1 cm
faults exceeding the plaster of 14 to 16 cm

And it is between these apparent failures that I would like to complete the insulation, with underneath the placo fermacell or other.

[Woodcutter]

[...]
For winter comfort, I was planning to supplement with 16 cm of insulation under plaster (16 cm available between the purlins .It seems that I have to reach 20 cm of mineral wool at least, but should I consider the existing thickness ?

Mineral wool ? Why mineral wool? There are lots of other more interesting solutions ...
If the current isolation dates from 1971, you can consider that it is more or less equivalent to ... nothing at all!
16 cm is better than nothing, but not enough in my opinion (and especially not enough to qualify for tax assistance ...).

[...]: arrow: For summer comfort, is it interesting to keep the ceiling of brick and plaster for its interesting inertia in thermal phase shift ???? Does it lose interest if the insulation is completed below?

Yes, the brick will participate in the phase shift, but not the inertia of the house as it is on the outside compared to the insulation.
The phase shift is not the inertia, do not confuse.

[...]: arrow: What insulator to take from this case: the wood fiber is it really more interesting than mineral wool or is it negligible if it is associated with a brick ceiling and plaster? In this case is rock wool superior to glass wool for thermal phase shift?

Wood wool, with a density equal to 55 kg / m3 (more dense, it is no longer "wool", but rigid panels) is much more efficient in phase shift than mineral wool, even if the LoR is a little better than the LoS ...

Roughly speaking, the phase shift produced by LdB is 4 times longer than "classic" LdV of equivalent thickness.
If you want more, it is necessary to pass in rigid panels, which are less and less effective in thermal of winter more they are dense.

[...]: arrow: Finally the house is located on a passage of planes, what would be the ideal insulation in complement?

For sound insulation, the most effective is the cellulose wadding in bulk ...

For your roof, and if the tile cover is from 1971, the best solution would be:
- transfer the existing cover, and the old LdV
- raise the roof by building a wooden box over the rafters, to have 30 cm to the bricks
- fill the casings with wet cellulose wadding,
- close with a rain cover
- re-read and retile to new.

With that you act on the insulation in winter (R = 7.9), the insulation in summer (phase shift higher than 10h), the acoustic insulation (reduction of about 50 dB of the external noises) and the regulation of the hygrometry of the House.