U-value log wall?

[MHelin]

Hello,

I have set a plumbing engineer to work on calculating the heating needs of my old log house. The problem is that he can't find any reasonable numbers on the U-value (k-value) of a 30 cm solid log wall.

Is there anyone out there who can help me with such numbers?  ???

/Magnus

 

[KarlXII]

30 cm is quite hefty!
A 6-inch log wall has a U-value between 0.88-0.93 and an 8-inch log wall has a U-value between 0.65-0.7 w/m2 K. Then you have to interpolate what suits you..

I would guess it lands around 0.50-0.55 with a quick estimation...

 

[MHelin]

Thank you for your reply Kalle XII, but unfortunately I'm talking nonsense.. :

30 centimeters is the total thickness of the wall, but the timber itself is not more than 20cm thick. I should have proofread my post before sending it.

The wall consists from the outside in of:

-1" Wood cladding
-Building paper
-200mm timber
-50mm sawdust insulation
-Raw planks
-Treetex fiberboard

In total, this is about 300mm, but the timber itself, as mentioned, is no more than 200mm thick. At least now I have values to provide to my HVAC consultant.

Just one more question K12, where did you find these k-values?

/Magnus

 

[KarlXII]

In my archive of useful-info that I gathered when doing some research for my own log cabin construction.

Likely from the Internet, but maybe in some construction book.

Since I saved it, I at least trusted the source.

 

[MHelin]

OK, that's enough to convince me.. ;D

 

[Nix]

I made a quick theoretical calculation and ended up with 0.40, which is quite low, considering that I have not accounted for leakage, thermal bridges, etc.

So Kalle's 0.50-0.55 holds up well as a practically applicable value against that calculation.