Gain crawlspace insulation on wood floor joists

[moby25]

Bonjour à tous

Here I ask myself the question of the real interest of the insulation of my floor which gives on the crawl space.

Inside I therefore have parquet placed on 22mm wooden floor.
This floor rests on joists.

Is insulating this floor really going to save me heating? I don't have a particularly cold feeling in my feet.

According to the figures the losses by the ground are the last. it also depends on the numbers

Another question I ask myself is what type of insulation to choose.

Given the configuration I would need something mis-flexible, so either wood wool panels or semi-rigid glass wool panel.

Given the hypothetical gain, I do not want to ruin myself in this isolation and I would leave on something not too thick. For example 4cm wood fiber panels to have an R of 1 instead of a currently low R.

For info on the rest of my house I have walls with 7cm of glass wool, 20cm of non-insulated cellular concrete, lost roof space on 20cm of cellulose wadding, habitable roof space 20cm packed at approx 15cm and recent argon double glazing.

This is also why I don't want to "go all out" for floor insulation when the other parts of my house are not very well insulated.

[stipe]

7m of glass wool, and you don't find that well insulated ???
In your place I would put 10 cm glass wool between the joists

[moby25]

Corrected, it's 7cm and not 7m

[Obamot]

Unless you have taken a job Corsica, the only wood that does not move [joke: "OFF"] it all depends on how is the access to the technical vacuum ...? (In general a few photos help to get an idea).

Personally I will do it because even if it does not at first affect comfort, it still constitutes a thermal bridge vector of humidity (and potentially air circulation), therefore mold and of air more polluted in pathogenic agents inside. And that is not very good, neither for the floor (since the wood is working), nor for the respiratory tract in certain cases (allergies, asthma, etc.).

Not knowing the place, the problem must be taken pragmatically:
- a floor can let air pass through a large volume, without being noticed (unless it is waterproof ...)
- the insulation would not prevent the house from "breathing", but at least the volume of air exchanged would be within the standards taking into account the rest of the insulation.
- a technical vacuum has, by definition, a degree of hygrometry and circulating air temperatures which fluctuate. To do so, we not only isolate but preserve (the wood will work less, ha, ha, ha,).
- I would therefore take a rot-proof insulating material.
- the insulation applied would reinforce the insulating effect of "the existing".
- it is not because it is the last point to isolate that it should be neglected;) in fact the isolation is to be considered as a whole.

But it's just a provisional notice ...

[moby25]

Wood wool can be advisable in my case then?

With or without vapor barrier? me I would not put it but hey all opinions are good to take

[Obamot]

It is above all on the roof that we want "it to breathe".

If it is to go on wooden panels, I would make a sandwich with something difficult to attack by rodents, like this in panels:



- and stick them squarely to the tar on the floor bottom side (a few nails on the bias of the epicutout).
- and tar to protect the insulation itself.

Problem is the adjustment, because it does not take too much play on the sides ...

Otherwise there is the solution of putting cellulose wadding in tubes between the joists (to contain it), then protecting it with ad hoc panels, nailed from below - directly on the joists.

We take the dimensions (and we check), we number the sections to be cut, we have them debited / numbered. Then we put them in the order provided for and as we insert the desired length of sausage, and voila!

The sausages rest on the panels. But it does not matter, because the residual space (air release above ... if there is one) also serves as insulation ... And air, it does not cost a kopek!

As long as you do, you can also do without cotton wool by using only panels, but then you have to seal with tar. The air trapped inside serves as a “free” insulation ... (be careful with the joints between panels which must be perfectly grouted, this is the only difficulty with this method, ditto from start to finish. meticulous, no stream of air must pass and the overlap on the struts must be generous => a construction can always "move", it is therefore necessary to leave room ...)

[moby25]

Tar does not really kick me, both personally and in terms of laying ;-)

I would like something a little more "clean" in the "organic" sense

Regarding the height of the vacuum it should be about 50cm

[Obamot]

Here are the two variants, the choice is yours:



In both cases it is better to end with a panel (protection against possible rodents, humidity, etc.). And in both cases it is the tar which lends itself best to it ...

All well-made foundation walls are tarred. There is no better and no real alternative.

It is an unprocessed therefore degradable hydrocarbon, therefore a natural product! I don't really see any rational reason for a reluctance, although I understand it. But it's a good amha souuce. It is very ecological insofar as the insulation inside the “boxes” is 100% recyclable in “natural air”! ^^

Because apart from the reliable tar in construction ... there are all kinds of salt ...... s more toxic than each other ... like silicone ... ^^

It remains much more "soft" than silicone, so if the house moves a little (the beams, it expands) the insulation continues to be optimal, therefore ecological once again over time, since the economy of heating is sustainable ... All this is barrels of oil or nuclear saved ...

Finally the quantity used is negligible (just a small joint ... ~ 3cm wide)

[aerialcastor]

It is above all on the roof that we want "it to breathe".

In fact it is not really that it breathes, but avoid the creation of a dew point due to the condensation of water vapor.

The problem is the same whatever the wall (wall, floor, ceiling). There is a balance of partial pressures of water vapor.
If the indoor air is more humid than the outdoor air, the steam will "try to find a way" out.

Within a wall, the more one goes towards the outside, the more the temperature drops, it is this drop in temperature which is likely to create the dew point: the colder the air the less vapor it can contain. 'water. (it is thanks to this property that an expert chooses his beer: the fresher will be the one that will have the most condensation on it )
It is therefore necessary to ensure that the water vapor cannot condense within the wall.
A simple rule of thumb says that the outside side is 5 times more permeable to water vapor than the inside side.

The choice of vapor barrier therefore depends on the outer layer.
So if the outer layer is completely waterproof (the case of tar), the vapor barrier must also be completely waterproof.
To tell you if we need a vapor barrier, we need to know what to expect at the bottom of the wall.

[aerialcastor]

It is an unprocessed therefore degradable hydrocarbon, therefore a natural product! I don't really see any rational reason for a reluctance, although I understand it. But it's a good amha souuce. It is very ecological insofar as the insulation inside the “boxes” is 100% recyclable in “natural air”! ^^

Ask those who install bitumen:
http://www.lepoint.fr/actualites-societe/2010-04-12/proces-le-cancer-mortel-d-un-ouvrier-du-bitume-devant-la-justice/920/0/443426

Even if the quantities are minimal, is therefore that there is no real risk the implementation is not very easy. You have to heat "live" without setting the joists and insulation on fire.

The bottom of the box can very well be made with a rain shield.
If there is access to the crawl space, it is sufficient for a stapler.
It is also a barrier to rodents.