Equivalence wood insulation VS concrete block + polystyrene

[pascal.boyard@gmail.com]

Hello,

I plan to build a wooden chalet of 40 m2, 40 km south of Paris.

I do not plan to add interior or exterior insulation.

I ask myself the question of the equivalence of wood thickness to have an insulation corresponding to concrete block 20cm + 10cm polystyrene + 1cm plaster.

44 mm or 60 mm?

Thank you for your contributions.

[Christophe]

Hi and welcome!

What polystyrene are you thinking of?

I copy you paste the method that I explained yesterday here: https://www.econologie.com/forums/isolation- ... 10693.html

You have to compare the respective R's, for this you have to have the exact wood you want to use. here are some wood insulation performance figures by species.

I think you can go, as a first approximation on a lambda of 1 for wood so 0.2 to 4 times less insulating than polystyrene ... in other words: 5 to 40 cm of wood is needed for an equivalent to 50 cm of polystyrene.

Here is the method:

Method: R = thickness in m / lambda

- The higher R is, the better.

- To obtain the R of a wall it is necessary to add the R of the different layers. To simplify, we usually only count the insulating part, assuming that it represents 90% of the resistance of the wall! Lambda concrete = 2 insulates 50 times less than a lambda insulation = 0.04!

- Physically: 1 / R gives you the thermal losses (= heating needs) for 1m² of wall and 1 ° C of temperature difference inside / outside.

Example: R = 0.5, 1 / R = 2 W / ° C.
5 wall m * 2.5 = 12.5 m²
Delta = 15 ° C

Losses = 2 * 12.5 * 15 = 375 W

2 R is the bare minimum currently acceptable for insulating a wall and 5 R for attics / roof. here are some recommended thermal insulation resistance values ​​recommended by RT2005 :

https://www.econologie.com/isolation-res ... -3511.html
https://www.econologie.com/rt2005-les-re ... -3512.html

You will find some lambda values ​​here:
https://www.econologie.com/isolation-lam ... -3478.html
et
https://www.econologie.com/isolation-pou ... -3477.html

The extruded polystyrene is 0.036 or 0.04 for example.

Here are some information on natural insulators:
https://www.econologie.com/les-isolants- ... -3168.html
and a very good subject https://www.econologie.com/forums/tableau-co ... t2977.html
https://www.econologie.com/eco-construct ... -3171.html

ps: do you know the Legnobloc? It is a block of compressed wood:
https://www.econologie.com/legnobloc-par ... -4334.html
https://www.econologie.com/forums/mur-en-bet ... 10487.html

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