log size, weight, and relationship to foundation support

[Merk]

Our home is presently 28x36, with an 8 foot covered deck supported by a king truss, and our logs are spruce, 12" median. This cabin rests on 8" poured walls. If one were to increase the size of the logs to 14" tops and 16"-18" butts, would the architect design the basement walls at 10"? Is there a weight variance between spruce and fir, with the same moisture level?

[Greg Steckler]

You say "basement" ....which is the deciding factor. If the retaining wall portion is 5' or less a 6" thick conc. wall is adequate. If 8' to 5' then 10" is adequate. If more than 8' tall then 10" is required....all with the appropriate amount and sizes of steel. The weight of logs is negligable since 5 and 1/2 sac concrete mix will take 2500 lbs per sq. inch. It's the side thrust of water soaked dirt that is what makes all the difference. :)