Holz Leichtlehm Dämmung 'U-wert'?

Wir sollten eine öko demonstration haus machen im Tchechien machen und haben damit ein frage uber die 'U-value'.

Die haus sind eine 100 jahrige alten sheuer mit ein konstruktion von 4 feldstein ecken. Wir wirden gern diesen ecke draussen isolieren mit etwas dünner als stroh, und suchen etwas mehr ökologich als polystyren.

Leichtlehm gefallt uns, aber wir haben diesen information gefunden und jetzt bin ich nicht ganz sicher...

Haben jemand von Euch erfahrung mit dieses problem?

Max Vittrup Jensen - www.permalot.org

" We hope we can get a good insulation ( conductivity < 0.1 W/m °C) with few straw ( < 50 kg/ m3) if we use clay or lime binder."

Important for the insulation value is the real density of the installed leichtlehm, to achieve a value of 0.1 W/mK the density would have to be around 300 kg/m³, which a group at University Kassel, Germany found very difficult to achieve and too weak for plastering. Workability would start
at 700kg/m³, but to achieve a reasonable insulation of k=0,3/m²K or R19 the wall would need to be 70cm or over two feet deep , which is likely to rot in the german climate.
Usual old leichtlehm as used in timberframes has a density of 1200 kg/m³ and 0,47 W/mK as stated in DIN4108 of 1969.

All information is taken from the "Lehmbau-Handbuch", Gernot Minke, University of Kassel.
Yours, Alex

clay

hi,
here some values of clay bricks and adobe:
Mixed with straw or rough wood shavings: density: 650 kg/m³, lambda value: 0,18 W/m.K), U-value depends upon the thickness of the wall. Heat accumulation: 200-100 Wh/(m³.K).

Mixed with small wood shavings or sawdust: density: 300, lambda value 0,12. Heat accumulation: 200-100.
Hope these data are sufficient for you, or do want some more?

yours
J.E.Hamesse

Leichtlehm as insulation

Thank you much for the reply: I'm happy for the values, and I'll save them for future use. ..[And thank you for writing English ;o)]

However to the best of my knowledge the bricks would insulate less than a mixture of wood-chips and clay slip poured into a shuttering. -As the bricks have to have more clay to remain stable while working with them.
Would you happen to have any measures for a max. insulative woodchip/clay wall?
-I'm competing with 10cm rigid foam insulation or 40 cm straw!

Sincerely, Max

clay 2

hi,
If your house should be used as eco-demonstration, don't use plastic foam (PU or PS). It doesn't suit together.
Building the wall with crude clay bricks ist like masonry, building the wall with adobe is like concrete. It is a different type of construction, but the results are almost the same.
clay with wood ships has a lambda value of 0,12
clay with straw has a lambda value of 0,18
The advantage of straw with adode is that straw works like an arming texture, which is not the case of wood ships. But you could mix both.
If you want to have values for clay, look at www.claytec.de.
Foam has a lambda value of 0.03 to 0.04
Straw has a lambda value of 0,13 which is near to clay with wood ships.
You could also use reeds or rush mats, they have a lambda value of 0.06.
Don't forget the other values of clay: heat storage inside the house. Clay is also known as bacterial killer (like lime plaster). It is also anti-allergical.
yours
J.E.Hamesse

further on insulation values...

)

Thanks! I'm well aware about the virtues of thermal mass/insulation along with the dilemma of rigid foam insulation..I may add that I last year arranged "1st European Natural Building Colloquium" ;o)

However, I'm still grateful for the values, and I'm embarrashed to have to admit that I forgot the solution you're pointing out: Using the thick reed mats! The colloquim was even hosted at a place which excels in this technique (www.biofalu.hu) (see www.permalot.org for photos Look for ENBC).

Thanks a lot for the information so far...only last questions now would be: Where would the condensation point appear when 2 reedmats gets applied directly to 70 cm Rock columns (clay mortar) and clay plastered on the exterior of the mats?? (Photos on www.permalot.org: look for Natural House)

Peace,
Max

condensation point

hi,
I don't have the appropriate software in order to calculate condensation points. This work is done for me by an engeneer. I presume however that the condensation point will occur just between the clay wall and the reed mats.
If it occurs at the fringe or slightly inside the clay wall, it doesn't matter, clay is able to store a lot of humidity without harm. The same if it occurs in the reet mats, reed has a natural capillary network, in order to spread humidity.
yours
J.E.Hamesse

Condensation point in rock/reed/clay

Thank you much Jean Elie; I'll bring you a good Czech beer if we happen to meet at Lehm 2005 in November ;o)

Over-and-Out,
Max