Isolated from the outside without coating?

[minguinhirigue]

What is the best insulation recommended for this type of exterior insulation: rock wool or wood wool?
The very small number of companies which could carry out this batch wish to work with wood wool. What do you think ? The argument seems to me more bogus and / or marketing than ecological. It seems to me that due to a too high concentration of wood outside, it is better to install rock wool as insulation.

The difference in insulating power is negligible between the two materials. At equal cost, my preference is for wood wool, which involves less gray energy than rock wool.

Companies, follow the wind, and it is in the right direction ... Well sometimes they surf a little too much on prices and margins, we agree

Should I start installing insulation (LR or wood wool) and cladding 20 cm above the ground? Is it better to insulate the base with cork sheets? In the latter case, can I put the wood cladding almost at ground level?
See you later.

If you want to put a wooden cladding less than 20cm from the ground, you have to put cork or another non-porous and rot-proof insulation on the lower part, and in front of the "planks to rot": the first two planks will be derail faster than the rest, you have to plan the blow so that you can change them easily. But with a class 4 wood, you are still gone for at least 20 years for the lower part, and more than half a century for the rest.

[Coati84]

Thank you minguinhirigue.

My preference for the choice of insulation installed outdoors goes for rock wool which presents a lower risk for the fire. How hard is it to find a company that could achieve this lot !!

My first budget estimates for my area of ​​55 m² are as follows:
- price of the cladding: 25 € HT / m²
- price of rock wool th. 10 cm: 8 € HT / m²
- accessories (rafters, dowels, rain shield, square paste, protective grid): € 30 excl.tax / m²
- labor: 4 days for 2 people or 330 x 2 x 4 € HT
- scaffolding: 800 € HT

The total estimated cost - including the company's margin - is € 6 excl. Tax [= 400 x (55 + 25 + 8) + 30) + 2] or approximately € 640 excl. Tax / m².
Is this calculation correct?
The first estimate obtained is € 1 excluding tax and seems too expensive to me.

I have noted the advice concerning the installation of cork insulation for the base. Here is my reflection of the day: is it serious from a thermal point of view not to start my insulation and the associated cladding at 20 cm from the ground?
It seems complicated to me to put cork, to manage the contact with the ground for the insulation and the cladding.

See you later.

[chatelot16]

cork is not the only solution for the lower part of the insulation

for me glass wool or rock wool is always the best, but wrapped in plastic to protect it and improve its efficiency

glass wool between 2 layers of polyethylene with forced ventilation at very low flow: it is not the most ecological materials but it is effective

and even for the insulation of the methanization tank filling of glass wool between the 2 layers of polyethylene with CO2: I would not dare to do it for housing

[minguinhirigue]

For the insulation of 20 cm near the ground, I think it is essential to avoid a thermal bridge which can constitute a source of losses of the same order as that of the wall or the entire floor.

Some thermal calculations show that in common cases, for a very insulated building (30 to 40 cm of roof insulation), when 1 kWh is lost through the roof, 2 is lost through the uninsulated acroterion thermal bridge.

Heat flows behave like water: the slightest crack and they rush in with joy. On a building, this can also result in excessive condensation around the thermal bridge and significant damage.

To treat the lower part of your building, we can indeed find, in addition to cork, encapsulated mineral wool solutions for the base parts. But I have some doubts about the durability of porous insulation in this configuration.

If a synthetic material is chosen, the best quality / price ratio for this use remains [unfortunately] polystyrene.

Others exist: cellular glass, cellular concrete ... but they are either more expensive, or less efficient, or both!

If the question is ecological insulation, cork remains the only insulation that I know of suitable for this use.

For polystyrene or cellular glass, no waterproof barrier required. The insulation goes down slightly into the ground 10 to 30 cm, the cladding goes down as low as possible (3 to 10 cm from the ground for the plank to rot), and the buried part of the insulation is covered either with a dark metal sheet , either with a bituminous coating, or raw if the aspect is not disturbing (no views of the insulation, vegetation present at the front ...)

For the risk of fire, it is indeed the only argument which one can oppose to the wood wool, but even in this case, posed under cladding, it lacks air for any combustion. The rain screen and the wood siding will be the first to catch fire.

For the prices, I cannot advise you for sure. Just, the hourly labor rates that you are announcing seem low to me if we include the costs of the company. the price of the siding too. But it depends on the wood chosen.

But these prices are possible, just a correction for the calculation, I find 6950 €: 125 € / m²
I find known ratios, but for large areas. You have to know on a small site, the costs of the company are often more important ...

Good luck, two more quotes and it's good ...

[chatelot16]

I wouldn't want a house completely insulated with polystyrene: it's too combustible

but for the lower part of the insulation from the outside I do not see the problem: the amount of polystyrene to put is so low

for me my glass wool between 2 layers of plastic is a question of economy: new polystyrene is too expensive for me ...

I even mix up scraps of ground polystyrene with old rotten glass wool ...

[Coati84]

Hello,

Thank you minguinhirigue for your precious advice. I will indeed specify in the "ITE" batch which will be drafted by my architect a cork insulation in the base.

I maintain my choice for rock wool insulation under the wood cladding.

For information, I would like to point out that the price of the cladding relates to the OPUS reference from the company PIVETEAU. The exact public price is 24.59 € HT / m² for a section of 22 x 135 mm. This cladding is in autoclave class 4 pine with a brown pigmentation during the autoclave phase. This cladding represents an excellent performance / price ratio. The price of Douglas fir cladding is around 40 - 50 € HT / m². Does my choice of class 4 autoclave pine look good to you?

The cost of labor - excluding margins - is 330 € HT for a worker for a day or 41.25 € HT per hour. This hourly rate seems correct to me and seems to me to be consistent with the rates specified in the BATIPRIX and FAIRE FAIRE reviews. What do you think ? What would be a satisfactory daily rate for you?

I meet an ITE specialist, carpenter-roofer by trade, the 1st week of March and will keep you posted.

See you later.