John Elliott wrote:In this case, "cold" means when the thermal mass of the cob becomes a negative, rather than a positive. To give a ridiculous example, building a cob house on top of some permafrost would not be a good idea. In that example, to keep the place livable, you would have to be continually heating all that cob and would get no benefit from the thermal mass, because there would be no time of the year that the cob could actually soak up and store some heat.
To really see if cob is appropriate, think instead about the time of the year that has the most pleasant temperatures. Is that March? May? July? The high thermal mass of cob will extend that pleasant time of the year, as it takes time to gain or lose heat to the environment. If it is pleasant in your area in a tent in April and October, then putting a massive cob structure around that tent is going to extend that time span to maybe March through May in the spring and September through November in the fall. You still have a few months when you need to heat, but not as many, and the same consideration about cooling in the summer.
If July is the only month when temperatures are halfway tolerable, and it freezes the other 11 months of the year, then if you build a house with a lot of thermal mass, you are going to be spending a lot of time heating that thermal mass.
Patricia Ramirez wrote:You're right Brian, there isn't much info out there about cob and cold climates. So the only way we could get the info, is to find it through experience. We built a small cob building to see how it performed up here in Northern Ontario. We planned on temporarily living in it throughout the winter, but the building department wouldn't have it. So regrettably, I can't comment on it's performance of having a continuous heat source inside while the temperature is below freezing on the outside. We plan on building our home with cob, but not until we give this smaller version a go. We plan on visiting our cob building. When I say visiting, I mean staying there for a couple of weeks (not living), and getting the heat turned up.
Patricia Ramirez wrote:The 'Why?' question is a good one. But I also ask myself, 'Why not?'.
Patricia Ramirez wrote:Up until stick-framing, log and stone houses was the norm in this area. Both utilize thermal mass, and they worked just fine.
Patricia Ramirez wrote:But they require a specialized skill in order to build them properly. I wouldn't call cobbing a specialized skill.
Patricia Ramirez wrote:There are oodles of reasons of 'why' we want to build with cob, but we can't find one 'why not'.
Patricia Ramirez wrote:...which is why we want to perform this test....
Patricia Ramirez wrote:There are many things that can be designed into a cob building to 'help' take advantage of it's thermal mass, but it will no way, as far as I can tell up here in the North, be comparable to a building that utilizes insulation. If you're curious if a thermal mass building works in cold climates, try to find a log or stone cottage, and give it a whirl. There are some differences with cob, but in regards to thermal mass, not many. As far as condensation goes, a fire will pull moisture out of the air, and an open (cracked) window should help as well. I think condensation will happen, especially when cooking. But as long as any moisture that ends up in the cob has a chance to dry, say throughout the night, then all should be fine. We'll find out on our test run, and make note of it on the website.
Sean Rauch wrote:
What I personally think is the most important aspect to planning a home build is efficiency so like J said rather than try and adapt a system you like to the world around you consider what system is most efficient in your area and work from there.
You wrote: "...I don't know if I used 'specialized skill' in the wrong context, but I think we can agree to disagree on this notion. When building our cob building I was more than happy to receive help from others to build the cob walls. Experienced or not, they could build the wall, the same way I would, with minimal instruction. I've never built a stone or log building, but I don't think an unexperienced person could do it properly. Cob is very forgiving in it's construction. I can't say the same for stone and log. True, there are a lot of things in cob buildings, as a whole, that do require a higher degree of skill and know-how, so I don't believe just anyone should build one. But building with cob, in itself, is pretty basic..."
Brian Harris wrote:What a great discussion.
I think we can confidently say that cob alone would be inadequate. So I've turned my thinking to hybrid designs: how would you "stick" interior cob to exterior straw bale?
If you could confidently link the two, then questions about load bearing abilities come to mind. And since I have a family I can't really move them into an experiment. Well, I could... but then they'd run away, write a book, and there'd be a documentary about dad's stupid house.
I'm not super pro or con anything so non-natural materials wouldn't be a deal breaker.
Maybe we need to have a 3 season cob home and a winter McMansion. Yeah... that'll do!
Sean Rauch wrote:
The simple answer is structural straw bale with cob as the wall plaster. Its done all the time, no worries.