Insulated engineered logs for cabin

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Small Cabin Forum / Cabin Construction / Insulated engineered logs for cabin


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bldginsp Member	# Posted: 15 Mar 2014 22:15 Reply A lot of people on this forum want to build log cabins. Logs don't insulate very well, but here's a company that makes laminated engineered logs that have thick foam insulation inside them that doubles their insulating value. Also because they are laminated and completely kiln dried they won't shrink much. Probably expensive, but solves some of the main problems with log construction. http://www.greatlakeslaminators.com/ (I have no financial interest in this- just ran across it on the web)

Nirky Member	# Posted: 16 Mar 2014 01:06 Reply In keeping a log home warm, logs are not required to be insulative. Rather, they operate on the property thermal mass, they receive heat from a source and store it, radiating that heat back. "Probably expensive" No doubt One can always throw money at anything to make it different, if one desires. To me something like this is a waste, but if one has the money...well I'm reminded what PT Barnum once said.

razmichael Member	# Posted: 16 Mar 2014 08:58 Reply Quoting: Nirky In keeping a log home warm, logs are not required to be insulative. Rather, they operate on the property thermal mass, they receive heat from a source and store it, radiating that heat back. I have to question this statement. Before building my cabin I investigated logs as an option (although I eventually went with standard framing, I loved the idea, look and feel of a log cabin). It became quickly apparent that the concept of Thermal Mass in a log cabin was very much misunderstood and, inaccurately claimed in many circumstances (mostly by log home companies). There is certainly an impact from the thermal mass effect (whether it be logs or masonry or other materials) but it does not replace insulation value, rather becomes part of the overall impact. Without going into great details (see the number of links below), the impact of thermal mass has the most value in specific climates where the outside temperature tends to oscillate above and below the inside desired temperature. This, therefore, is much more useful in warmer climates and when discussing the cost of cooling a home. When dealing with colder climates, thermal mass can play a part but it must be considered in conjunction with passive solar heating and a number of other factors. If you are trying to heat your house/cabin when it is -20 outside for months on end, thermal mass is not a lot of help because the "radiating it back" also refers to radiating it to the outside. Here you need plain insulating capability. I fully understand that there are so many factors involved in understanding and designing (for heating and cooling) with both logs, cavity insultion and just general construction. In all of this thermal mass can play a part but it is not the whole thing and, if you plan on assuming it will keep your cabin comfortable, you need to make sure you really understand what part it plays. Building Green Article Inspectipedia Article good article that highlights parts of various studies that are often not used when organizations quotes bits and pieces. This is also interesting because it notes that the often cited DOE study has errors when calculating the base line R-value depending on the log shapes. GreenBuilding Advisory Again explains some of the concepts and discusses why, in really cold climates, thermal mass will have little impact. Also goes through some of the passive solar things that can be done. Again, I love log cabins or homes and wish I could have afforded the time and money to do my cabin this way. There are many ways to ensure suitable construction to meet heating and cooling needs but it is not purely by thermal mass.

Don_P Member	# Posted: 16 Mar 2014 09:19 - Edited by: Don_P Reply Edit; I typed too slow , Well, more fodder The thermal mass concept is probably overly relied upon by most who want to take advantage of it. First it requires... mass, a lot of mass to overcome the basic heat loss. In wood this effect doesn't really begin to kick in below about 8" thick. Second, think about it more as a thermal flywheel, as the temperature differential between desired indoor temp and average outdoor temp increases more mass is required both to insulate from the outside temp and to store the average desired indoor temp. Masonry or water are other ways to create a thermal mass wall. The resistance to the flow of heat is very low in those materials so it is easier to understand that although they would store heat and rerelease it to the indoors thus evening out the average daily temperature swing, the flywheel effect, the heat loss to the outside would be terrible. Wrapping those walls with insulation on the outside makes them very effective mass walls, evening out the swings in temperature. Wood has an R value of about R1 per inch of thickness and has fair mass. The denser the species the greater the mass but the lower the resistance to the flow of heat. As is generally the case, there ain't no free lunch. Wrapping it with insulation and storing the heat inside that envelope within the wood mass does have merit, I doubt the cost/benefit is going to be the best. Using a thinner uninsulated log is going to be more akin to the concrete wall problem, the colder the outdoor average the worse that equation gets. It's also worth noting that the mass study most people cite from DOE was done near DC where the average temp was pretty mild, travel north where the average is much colder and the mass/ insulation problem needs deeper thought. If you're cleaning up the forest for heating, not such a big deal... sort of akin to those "high efficiency" wood boilers that the slick salesmen are selling all around me, thankfully the woods need cleaning up cause those folks are surely having to do it, but do go in with your eyes open.

MtnDon Member	# Posted: 16 Mar 2014 11:55 Reply ... then there is the potential problem with part time winter use of log structures. The mass of the logs works against you when you arrive for a weekend and try to warm up the place. It might be comfortable about the time Sunday night rolls around.

bldginsp Member	# Posted: 16 Mar 2014 11:58 - Edited by: bldginsp Reply I agree Don P and MtDon. Log just doesn't stay warm below freezing, despite the help from thermal mass, so you burn a lot more fuel. This 'insulated log' idea appears to deal with the issue well, but I wonder at what price. They say that the more you buy the less they cost per lineal foot because of milling efficiency, but they don't quote any prices. Because its a milled product, manufacture of the building and assembly are probably much less labor intensive. Then there is shipping, they are in Michigan, so probably not a viable option west of the Rockies. I wonder if there are similar operations on the west coast. Because of energy regulations here in California, its very difficult for new log homes in colder areas to meet those requirements. I guess the trend nationwide will be toward greater energy efficiency in all buildings, so it could be true, as they claim on their website, that they are the future of log construction.

razmichael Member	# Posted: 16 Mar 2014 12:03 Reply Quoting: MtnDon The mass of the logs works against you when you arrive for a weekend and try to warm up the place. It might be comfortable about the time Sunday night rolls around. Hard not to go back to the music video posted by obtusemoose399 last month Music Video - My Cabin with the line "right now it is icy cold but in 16 hours it is going to be hot".

Don_P Member	# Posted: 16 Mar 2014 13:08 - Edited by: Don_P Reply I've built a few insulated, or half log, log homes. There is a conventional 2x6 stud wall wrapped with 1" polyiso and then 2-5" thick half logs outside and sometimes inside, sometimes panelling or drywall. They have high R values and if the heavy half logs are inside they do have mass inside the insulated envelope. One side benefit is that if there are rot problems on the exterior it is much easier to replace a bad log. Since they have been sawn there has also been a stress relief and there is much less checking. To see how that works go up to a milled log home, they typically have full logs up to 8' and then log siding in the gables ends. Notice the checking in the full logs as compared to the log siding. Not advocating one or another just observations. bldginp- I've seen Sing log homes advertised for several decades, I believe they are west coast. I've seen unhappy customers as well so just info, no experience. Many companies make some form of log look insulated system. To my mind building up a wall system with more continuous sheets of foam is going to outperform a "log" wall stack with its' many lateral joints. Again just stuff to consider.

bldginsp Member	# Posted: 16 Mar 2014 15:04 Reply People like log cabins for the look, but the more you engineer the problems out of the logs, the less they look like logs and more like engineered, milled timber products. Might as well just use log siding like Don P suggests. Which leads me back to my original decision when I considered building log- it's not really worth it, you can build a better performing building for less money that's easier to build using standard stick frame. So I compromised with stick frame walls and site cut log rafters for a vaulted ceiling. But still, many people have this idea in their minds of a log cabin in the woods like Abe Lincoln. What they don't know is that Lincoln wasn't proud of his rural, log cabin upbringing, and as soon as he and his wife could afford it they bought a nice saltbox.

MtnDon Member	# Posted: 16 Mar 2014 15:33 Reply I've been told that the reason squared off logs were used in some places was that as the family could afford it, they would then apply siding over the squared log faces to hide the fact that it was a log building. The inside might be paneled or sided as well or plastered. That could also help with draft reduction. I DO like the appearance of some log buildings, but that is as far as my desire for one goes. We have friends up in the mtns here near our cabin who have used 2x6's to give log appearance on the inside of the frame. Outside was done in log-look milled siding. The difference with the inside is the guy hewed the inside faces of the nice 2x6's to give the appearance of hewn logs. The guy is an artist, good enough to actually make a good living from his talents as a sculptor. We have an eagle he did. He carried off the interior fakery extremely well. I think Ronald is now 86.

Don_P Member	# Posted: 16 Mar 2014 21:40 Reply I go round and round, I do enjoy working in timber and there are some advantages to a non cavity wood wall. Another thing to consider, I've built walls with pretty high R values... and then put windows and doors in them. sort of like putting on a down parka but not zipping it up. I like plenty of light but there's the other side of the issue when we say log walls don't perform well, neither does glass. I agree with MtnDon, the hewn historic log homes here were often just a horizontal framing sytem that was a fast way to get under cover. When the family had the time and money they covered their humble beginnings with furring strips, white clapboard and plaster. Often the logs around here were our southern hardwoods, oaks and poplar. The powderpost beetles would move in searching for starch and leave little piles of very fine frass, colonial baby powder before talcum powder was readily available.

Nirky Member	# Posted: 16 Mar 2014 21:50 Reply Razmichael, I wrote "In keeping a log home warm, logs are not required to be insulative. Rather, they operate on the property thermal mass, they receive heat from a source and store it, radiating that heat back." So my points you are questioning are 1) logs are not required to be insulative; that is, they do not rely on their insulative properties to keep a log home warm 2) The typical log home relies on the logs' thermal mass to store heat & radiate heat back R value is thermal resistance, a resistance to change in temperature. The R value of softwood, which wood most log homes are built from, is about 1.4 per inch. So 6-inch log walls would have an R of about 8.4. That's not much of insulation for the walls of a home in a temperate climate, let alone say an extreme one, like, say, Alaska. Yet people in Alaska DO live in log homes with 6 inch walls. At least one person who frequents this website does. He survives in minus 20 with 6" R8.4 walls. Point #1 he does not rely on his R8.4 walls to keep his log home warm, does he? Nope, something additional is happening. All materials have an R value and all materials have a thermal mass. As a rule a material with a high thermal mass has a low R value, and vice versa. Inversely proportional. It's not that logs have only thermal mass and no R value, or that pink insulation has only R value and no thermal mass. It's simply physics. Yes, a log radiates it's heat energy outside the home as well as back into the home, as I was giving example. I had no idea someone would take it that I was claiming logs radiate heat unidirectionally! Overall, log homes take more energy to heat than a stick home, but the trade off is the look & feel, plus cost; you do not pay $$ for insulation or sheathing or siding or sheetrock and you will not ever be breathing in hidden mold or formaldehyde. Of course you could pay more than stick built if you went with a "kit" log home, but a traditional log home built with simple pioneering techniques is what I have in mind here.

Malamute Member	# Posted: 16 Mar 2014 23:36 Reply No disrespect meant to anyone that has participated, but I see a lot of theory, and very little "I did this or that" with regard to experience living in log. I've built and lived in several handbuilt log cabins over the past 20-some years and have never felt them to be difficult to heat, and it's never taken days to get them comfortable after being away, more like an hour or two after getting the fire going. They are harder to get airtight, but for myself, that aspect is handle-able, and something I accept for my appreciation of log cabins. Whatever theoretical or practical advantages modern construction has over log, so far it hasn't lured me away from log in any way. I just havent experienced many of the things people keep mentioning as disadvantages of log.

bldginsp Member	# Posted: 16 Mar 2014 23:54 Reply Malamute- thanks for the real, practical experience. What temperature ranges have you lived in, in your log cabins? Did you notice a large, or not so large,difference in fuel use as the temperature went to the lower extremes of your range?

Malamute Member	# Posted: 17 Mar 2014 00:05 Reply It will get 20 below F off and on through the winter, 0 off and on isn't unusual, though we can also be in the 30-40's in the daytime. Yes, it takes more wood when its colder, I think that's common with any house though. When its 50's in the daytime (which would be 20's to 30 at night), I often don't make a fire at night, it gets coolish, but putting on a long sleeved shirt is often plenty if I feel lazy and don't want to make a fire. My current place is small (14x18), and not at all difficult to heat no matter what. The larger places I've lived in or built and sold haven't been that difficult to heat either. Comparing notes with other people that heat with wood or propane, nobody is coming up with any drastic differences for similar size houses. That may not fit with people ideas of how it should be but its what I've seen. Build two identical places, one each of log and frame well done and maybe there will be a noticeable difference, but I don't think it will be as much as some expect. That's just my take on it.

Don_P Member	# Posted: 17 Mar 2014 06:44 - Edited by: Don_P Reply I've done "this or that" with log somewhere north of 50 times in a number of climates. Some have been easier to heat than others. I've been in some that were quite comfortable, some took several days to warm up and others that always had cold walls in cold temperatures, not much different than a cold window on a cold day. Can you heat it, sure... that is the something additional Nirky alluded to, apply enough heat and you'll be warm in a teepee. Definitely if there are drafts, not much else matters... or as on teacher said "Take care of infiltration, then insulation, then insolate". Going back to theory, or the energy code, this is the table that we've been kind of dancing around for the physics of it, kinda big, I'll just link it rather than posting; http://timbertoolbox.com/sketches/logR.jpg The left column is the specific gravity of the wood species (cedar and softwoods run about .36, red oak about .67), the top heading is the average log thickness, the cells are the approximate R value, and to the right of the stairstepped bold line is where the energy code says the thermal mass effect starts becoming a realistic factor, the the left you're really just working with the R value. They drew a line, we all know reality doesn't work that way but they have to pick points somewhere once they decide to regulate things like energy efficiency, which is I think where the op was going. There are several more pages of calculations on applying the mass effect but the easy way to apply it and balance the options is to use a program like ResChek from the DOE website if you're in an area that requires a level of performance. Generally with some tradeoffs they can be made to work. I've never had a homeowner that was denied after making some changes in other parts of the structure. And yes, I've lived in old houses that made a tight log house a dream. I've built very well insulated houses that made logs look pretty antiquated, there is quite a performance range out there in the real world...then there is the issue of the embodied energy in the construction itself, but that's a whole nuther can of worms

revid Member	# Posted: 3 Apr 2016 07:32 - Edited by: revid Reply Iam in process of building a log cabin(24x28) here in eastern Canada.My logs are 8" with two flattened top and bottom sides .They are all Balsam Fir.I thought I read somewhere that a 8" log is comparable "R" wise to a 6" insulated wall? Here it gets pretty cold in winter and after reading all the above posts got me wondering about how hard it will be to heat the place.I intended to use the cabin just on weekends but it sounds like it will take me a couple of days just to heat the place and by the time it gets cozy I will have to come back home! Got me thinking now if its a good idea to build!

bldginsp Member	# Posted: 3 Apr 2016 09:47 - Edited by: bldginsp Reply They say that in general you get about R1 per inch of thickness with wood, giving you about R8. A typical 2x6 wall has R19 insulation in it. Given Malamute's experience in sub zero temps in his log buildings, I don't think you should abandon your project. But I do think you should do a lot of insulation in your roof and get a woodstove that is on the large side for the square footage. I think the upshot of all this is that, by the numbers, log buildings are less efficient than others, but that just means you have to burn somewhat more wood. If the roof is well insulated, the walls are tight, and you have good woodstove and a good pile of dry wood you will be fine. Malamute's experience that it only takes him a couple hours to make the building comfortable makes sense. What you are trying to do is heat the air, of course, but the problem is that all that log mass takes more than a few hours to heat up from freezing. Still, with a little extra wood on the fire, you will keep the air warm inside while the logs warm up. Come Sunday night the logs will finally be up to temp, but you will have been comfortable the whole time, except perhaps in the back bedroom furthest from the woodstove. That's why they make down comforters. A second small woodstove, in the kitchen or back bedroom, would definitely keep you cozy. But the energy numbers crunchers in da gubmint don't want to hear that.

toyota_mdt_tech Member	# Posted: 3 Apr 2016 12:42 Reply Quoting: Malamute No disrespect meant to anyone that has participated, but I see a lot of theory, and very little "I did this or that" with regard to experience living in log. I've built and lived in several handbuilt log cabins over the past 20-some years and have never felt them to be difficult to heat, Agreed. My dad and myself build a small 8X12 log cabin tool shed, it was all saddle notched and scribed to fit well. Chinking was done with cedar bark. In a hot summer day, it remained ice cold in it all day long. It would only warm up if I opened the door or window to let the hot summer afternoon heat it. Same for keeping it warm in the winter. Very small woodstove and a small fire, once it was warm, it stayed warm an in the dead of winter. I shudder at the thought of log homes being regulated out of existence. They are trying it with woodstoves now.

Topper Member	# Posted: 3 Apr 2016 22:07 Reply Quoting: Malamute but I see a lot of theory, and very little "I did this or that" with regard to experience living in log. According to theory, bumble bees cannot fly... - Fairbanks, Alaska. - 8" log 24x26 story & a half. - weeks on end of 40 below with some 50 below, throughout the winter. - Toyostove only. - perfectly comfortable.

bldginsp Member	# Posted: 3 Apr 2016 22:28 Reply How many cords?

Don_P Member	# Posted: 3 Apr 2016 22:30 Reply Quoting: toyota_mdt_tech Agreed. My dad and myself build a small 8X12 log cabin tool shed, it was all saddle notched and scribed to fit well. Chinking was done with cedar bark. In a hot summer day, it remained ice cold in it all day long. It would only warm up if I opened the door or window to let the hot summer afternoon heat it. Same for keeping it warm in the winter. Very small woodstove and a small fire, once it was warm, it stayed warm an in the dead of winter. This describes the thermal flywheel effect of the mass. In the summer the interior was not ice cold, it was approaching the average temperature, which, at midday in the summer seems quite cool. In the winter same thing except there is added heat. Quoting: toyota_mdt_tech I shudder at the thought of log homes being regulated out of existence Well, keep in mind what we see enforcement-wise, most inspectors don't know anything about the log home standard that is referenced by the building code. That standard was in large part the result of efforts by Robert Chambers... yup, same guy that wrote the book y'all were promoting on the other thread. Without a "standard", a prescriptive path to do something, the building codes say you need engineering. Again think about how often things are enforced, I had engineering done a handful of times when requested. However, the letter of the law until 2007 said that every log home needed engineering. If you build the same detail many times and the engineering comes back the same every time, that's when it makes sense to create a standard. Anything built within the methods described in the standard are prescriptive, only when you step outside of that do you need an engineer. When people say the government did this, well, it's not that simple. This was a private businessman who was also president of a log home guild, trying to make an easier path. The timber framers are slowly moving in the same direction. It is a mixed blessing for sure. The regulations have been there for quite a number of years. Enforcement has, and continues, to vary greatly. The standard is a relatively recent prescriptive method to make it easier to comply with the old regulations. Log homes are in no danger of being regulated out of existence. Revid, at 20x24, if you can't heat it you've either ignored bldginsp's advice or there are air leaks. It is much easier to have a leak when there is a horizontal joint around the building every 8". I am assuming you mean the logs are flattened to 8" tall, which would normally take logs that are ~10-13" wide. 12 courses If you meant the logs are only 8" wide then they are probably no more than 6" tall when flattened, 16 courses. If this is your plan think about the greater number of lateral joints and the difference in mass compared to the wall above. I'm not pointing in a direction, just pointing things out.

skootamattaschmidty Member	# Posted: 4 Apr 2016 03:35 Reply I have a log cabin in eastern Ontario. In the winter it regularly gets to -20C outside or colder. I regularly go up for weekends during the winter and have arrived and it's been -20c inside the cabin. We usually arrive by mid morning and we start a fire right away. Within a couple hours it's comfortably warm. By the end of the day it's very nice and the logs have warmed up considerably. Certainly I use more firewood during this warm up period than I do the following days. So Revid,if you are thinking the log cabin route, don't be discouraged about weekend trips in the winter. If you build a quality cabin with good fits between the logs and in the corners you should not have any issues.

Topper Member	# Posted: 4 Apr 2016 11:49 Reply Quoting: bldginsp How many cords? If you're referring to my post, not a single stick of wood. Toyostoves run on heating oil.

bldginsp Member	# Posted: 4 Apr 2016 11:57 Reply How much oil, compared with a similarly sized house frame built with current insulation? Wondering if we can get a sense of how much more/less fuel it takes to heat a log home through cold winters.