Log home res check zone 6
dfvellone
| Posted in Building Code Questions on
I was speaking with a local log home builder who expressed his experience with local code enforcement and the res check on a new home he’s building. Because of the limitations of the insulative value of the log walls he was required by the codes officer to bump up the r-value of the basement walls to r-49 in order to meet the requirements of the res check. So, rather than building a home that’s insulated to minimum standards the numbers are played with for an end result that satisfies the paperwork.
I know that the codes officer has final say, but this seems nuts to me.
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Why is this nuts to you? ResCheck has the "tradeoff" option, where the building's total UA value is considered.... I think it's better than demanding "minimum R49 attic and R19 walls)....when someone has a huge bank of windows....making up for it with R60 in the attic to "Even out" the energy loss of the building makes some sense to me.
It seems wasteful. Putting r49 on the basement walls may balance the numbers out, but ultimately the low u-value of the log walls will still make heating the house inefficient. Don't you think?
Edit: maybe I should instead ask, will putting r49 into the basement walls compensate for the walls?
Thanks, Daniel
Well, that's what Res Check can do, from my understanding.....it makes sure shortfalls are compensated for elsewhere when you use the tradeoff method. Not sure how accurate it is as far as assumptions for ground heat loss, etc....
So, while I agree log walls don't have the lowest U Value, I can understand the code officer's stance.... Do they (or should they) care that the UA is achieved through a combination of a highly insulated assembly combined with a low insulated assembly vs a mediocre assembly all around? If the building, as a whole, is compliant, I think that's all that some are looking for.
Also, some interesting numbers and info here: https://www.nachi.org/loghomes.htm
IMO what's nuts is building a log home to begin with.
John,
I agree. Log homes were primarily used as a building method by people who had land with standing timber and few tools, or choices available. Their only merit is aesthetic.
Check out parallel heat flows. https://www.greenbuildingadvisor.com/article/the-fundamentals-of-series-and-parallel-heat-flow
The math *may* work out (and not just on paper) but the reason it is crazy is because you need SO much in one place to make up for a lack in another. Same concept as to why continuous insulation is so effective. This is sort of the opposite end of that spectrum, requiring disproportionate thickness and cost in one area (basement) to make up for poor performance in another (log walls).