Old log farmhouse: single component spray foam between logs before re-chinking? Off-gas possible?
Hello builders,
I am renovating an 1872 log farmhouse and have torn out the chinking between the logs. Gaps between the logs vary from 0″ (touching) to almost 5″. This is a pioneer-built house.
The house has been strapped and sided on the exterior, so I only have access to the interior. I want to insulate between the logs before re-chinking with mortar.
The obvious insulation would be single component spray foam in a can. But I am worried about off-gassing long term. There will be a fair amount of foam to be used, maybe almost 1000 linear feet of gap to be filled.
In 2013 Martin Holladay wrote “I’ve never heard of lingering odor problems with one-component foam.” Response # 138 in:
Is that still your experience, Martin?
Do others have experience or opinions?
And if not foam, what other product would you suggest? I think mostly of jamming Roxul in the gaps, but its not much of an air infiltration barrier, and since there’s no exterior chinking, there would be cold air movement right through the Roxul and up against the interior mortar chinking. Not great.
Thanks,
Eric
Ontario, Canada
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Replies
Eric,
Back in the 1970s, my friends used oakum to chink their log homes. But times have changed. Current advice seems to favor special products sold for this purpose (synthetic chinking). I have never used these products, so I can't advise you on brand names. Here are some links:
http://www.loghelp.com/categories/chinking.asp
https://www.permachink.com/log-sealants/perma-chink
http://www.logrepair.com/log-home-chinking-and-caulking/
Hello Martin,
Thanks so much for responding. I'm from Vermont, too, the Shrewsbury and Plymouth area.
I get the oakum history and its appeal. And I understand the newer chinking materials. Up here, people use a white Portland cement based mortar to achieve a white masonry chinking which works well and looks very sharp. It is embedded in expanded metal lath which has been air-stapled into the gaps, and it doesn't come out easily - even when you want it to.
My question is mostly about insulating behind the chinking. And mostly about off-gassing of single component spray foam. I know the horror stories of spray foam. It seems that its mostly two part foam, mixed incorrectly by operator error. So my question is mostly whether there is a problem with lingering off-gas problems with single component spray foam.
I will attach a photo so you all can see. The gaps get large enough that I want a real source of insulation in them before chinking. And since I can't chink from the outside, due to the siding on the house, I want an insulation which isn't vulnerable to air-infiltration.
But of course I do not want to toxify my old naturally-built house.
Thanks much,
Eric
Here is a second picture, to show how large the gaps get. This is the "worst" section of wall. Most of it is tighter than this.
-Eric
Probably you all know, but if you click on the picture, you get a larger version. Then you can see in detail the handiwork of the farmers of 1872.
-Eric
Eric,
To answer your question, I haven't heard of any problems with lingering odors caused by single-component spray foam.