Possibility of mixing different types of insulation

[newstarnord]

Hello,

I would like to ask some information about thermal insulation.
We have a house of 60 years, insulated roof with 25 cm of glass wool or rock.
However the attic is uninhabited, unheated at present.
So I put the glass wool on the floor (concrete floor slabs) where I could and in places of circulation, polystyrene.
But what is certain is that there are thermal bridges in this pseudo-isolation; no way to do otherwise because the attic is congested.

The walls are insulated by an air gap - which seems well sealed - from 5 cms between the wall and wall which are made of brick about 3 cm and 12 cms.

In some rooms, on some walls, I injected vermiculite.

I would like to know if the walls on which the vermiculite is not injected create or not thermal bridges, although they are waterproof, but less well insulated? Is there an interest in having only one isolated wall if we can not immediately isolate all the walls? And if the vermiculite is not so well distributed that it will be effective anyway?

And if I decide to isolate a portion of wall with dubbing placo, while the whole room is not isolated in doubling placo, is there any interest?

According to my calculations on toutcalculer.com, even if the vermiculite is not an isolator so powerful that considering current what the current, the thermal gains could be rather important (kind 50% reduction of the consumption of fuel / elec for insulated vermiculite walls, see more)?

Thank you in advance.

[newstarnord]

Hello,

Maybe my question is too complicated , so I'm going to make it simpler: is there a drawback to insulating one wall more than another, let's say that two walls are on the outside, if one partition is insulated with vermiculite and the other by airtight airtight, is the vermiculite effective or the thermal bridge created by the less well insulated partition (just by airspace) will remove the thermal benefit provided for this other partition?

thanks in advance

[Ahmed]

A simple air gap between an exterior wall and a partition is not an optimal solution, since convective currents * will be established between the two walls: it is imperative to immobilize the air by a light filling .

* A blade of cold air will plunge along the wall and then come to lick the partition to rise as it heats up, etc ...

[sicetaitsimple]

Maybe my question is too complicated , so I'm going to make it simpler: is there a drawback to insulating one wall more than another, let's say that two walls are on the outside, if one partition is insulated with vermiculite and the other by airtight airtight, is the vermiculite effective or the thermal bridge created by the less well insulated partition (just by airspace) will remove the thermal benefit provided for this other partition?

Generally speaking, I would tend to answer no if we are talking about surface insulation (a wall). Of course at the interface between two surfaces
(two walls for example) differently insulated there is a risk of heat transfer, but it will remain limited in extent.

PS: to complete Ahmed's answer, a real "vacuum" of air would certainly be effective, but in practice, it is "full" of air! So effectively a non-zero efficiency, but limited due to the convective movements of this air.

[Christophe]

A simple air gap between an exterior wall and a partition is not an optimal solution, since convective currents * will be established between the two walls: it is imperative to immobilize the air by a light filling .

Or a regular lathing ... see this interesting subject from 2009: heating-insulating / isolating-of-walls-vertical-with-blade-and-air-and batten-t8971.html

[Christophe]

2 other topics on air knives:

heating-insulation / insulation-by-fill-of-insulator-for-empty-and-a-wall t10177.html

heating-insulation / blade-to-air-ventilated-in-house-stone-t14580.html

[Christophe]

so I'm going to make it easier: is there a drawback to insulating one wall more than another, let's say that two walls are on the outside, if one partition is insulated with vermiculite and the other by vacuum air tight, is the vermiculite effective or the thermal bridge created by the less well insulated partition (just by air space) will remove the thermal benefit provided for this other partition?

thanks in advance

Not so simple lol!

Everything is calculated: estimate the R of each partition and measure their surface and for a temperature delta (interior - exterior) you will have the losses per wall and total for the room.

In fact your question is a bit like asking "If I open the window (= wall with 0 insulation) does that cool the interior (= the other insulated walls)"?

The risk with differential insulation is that the coldest wall may condense ... but a small insulation is still better than nothing

ps: I do not answer the question of the air gap because it was treated in the 3 subjects that I have just mentioned.

[newstarnord]

Thanks for the answers.

Or a regular lathing ... see this interesting subject from 2009: heating-insulation / insulating-vertical-walls-with-an-air-knife-and-lathing-t8971.html

If I understand correctly it would "suffice" a heat-reflective film on the wall with air vacuum to achieve the performance of styrodur.
By bad ! However, this film must not be covered otherwise its thermoreflective effect will be eliminated.
By cons on the partitions of the rooms there was a thin sheet of polystyrene 3-4 mm (product with a specific name that I forgot).

Off topic

On the other hand, I noticed that perlite would on the one hand be more effective than vermiculite at the level of the coefficient R, and it does not "drink" water unlike vermiculite (which is nevertheless rot-proof)? Only constraint: to bring it by truck. While vermiculite is available in some GSBs.