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Small Cabin Forum / Cabin Construction / Easy and Cheap Log Cabin
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Stoney
Member
# Posted: 22 Oct 2010 04:13
Reply 


OK,
Going by your numbers, a 12 inch wall would be necessary to pass the energy codes as they now stand.
If this were true then most log cabins being sold today, including others being shown on this forum, would not meet this standard.
This doesn't pass the smell test for me. I suspect that that the Rescheck site only takes R-value into consideration and does not consider thermal enertia.
This is why I want all the readers of this forum to understand that everything being said by "Experts" on this forum or any other forum should be taken with a grain of salt and to discuss all building plans with their local building inspector.

Gary O
Member
# Posted: 22 Oct 2010 07:09
Reply 


Yeah, thermal inertia, looked up the term. Looks like a great argument in the offing, for the staid codes and regs of today.
And, it seems to make sense in this ol' geezer's mind.
Been in a lot of tight (small log) structures that just plain stay warm.....

MtnDon
Member
# Posted: 22 Oct 2010 10:26 - Edited by: MtnDon
Reply 


All I was doing is pointing out the problem that could be encountered if someone was planning to build a structure like this. If an area, a state, is working under the Dept of Energy Efficiency Codes, as mine is, the plans would have to go through the RESchek program.

In the example I used, we have a lot of windows. Making windows smaller would increase the rating. Using windows with argon gas filled low-e glass would increase the rating. Increasing the ceiling/roof insulation would also increase the rating. I picked that plan as it passed the way it was.

As for other log structures passing the RESchek, maybe they wouldn't pass or maybe they would. Maybe where and when they were built the code was not in use or enforced. Maybe they have a lower percentage of window area than my building. Or maybe the permitting process was bypassed; people have been know to do that. There are lots of maybe's.

The geographic location also matters. Northern or high elevation mountains are going to have greater demands on the insulation or thermal qualities of the structure. My example was for high western mountains. A more moderate climate will be different.

The download site also has document downloads that explains how all the input data is processed and thermal mass is processed in all the later version of the program. Wood species is taken into account. I've also been told by independent contractors who have built genuine log structures for decades that thermal mass does not "kick in" until the log square cross section hits 7 inches or so, with most species. Some, like white and red oak and long leaf pine are effective in 5 inch cross sections. Others like white and red cedar are ineffective in sizes smaller than 9 inch.

There is a lot of science, a lot of lab work performed with building sample section walls and running them through testing. It is not purely theoretical work.

I'm not necessarily saying this is how things should be (government telling us what to do), I'm saying that this is what is in place in more and more locales. On the other hand today's more energy efficient buildings are better than the way things were done in the 1950's. I don't think there can be any argument about that.

Have any other viewers here submitted plans for inspection through an agency that uses RESchek? I know of several people who have and have had to modify their designs before they could pass. Even if the owner-builder thinks it is wrong, if the rule is in place, how does one get around it?

All I wanted to do here was point out what I saw as a potential problem. Better to be forewarned and prepared than to be surprised. It would be very interesting to see what would be encountered when applying for a permit to build a cabin with this method in an area that uses the energy codes.

I still like the looks of the garage. I forget if I mentioned that I ran approx cost of materials numbers for a wall section; "log" vs stick built with osb sheathing with f-glass insulation, housewrap, and T&G 1x8 pine inside and outside and the conventional came out as more costly (mainly because of the real wood T&G in&out).

http://www.energycodes.gov/training/onlinetraining/rescheck_loghomes.stm

I won't say a single thing further on this unless someone indicates they want to pursue the topic.

toyota_mdt_tech
Member
# Posted: 23 Oct 2010 23:01
Reply 


Yes, I"m sure it wouldnt meet R specs. He did build it as a garage, so if there is no heat initially in his garage, he doesnt need to worry about the R factor. It certainly looks stout enough to pass the tough test. Basically solid wood.

Stoney
Member
# Posted: 24 Oct 2010 05:26
Reply 


I have suggested to others on this forum that to increase the performance of this building to simply add an additional 2" by to the inside walls. This would bring the outer walls up to the full 6 inches and provide an easier method to conceal wiring. This would be much easier than boring holes as tipically done. I would put my building up against any other commercial log cabin with 6 inch walls.
The building could still be built as I have indicated for any other structure, (sheds, playhouses etc.) where heating and cooling are not a critical issue.
I am still trying to find out how the commercial log cabin companies can pass energy compliance with 6 inch walls. My building inspector could not answer the question. He simply stated that the architect I would choose to draw the plans would make the calculations.

MtnDon
Member
# Posted: 25 Oct 2010 16:18
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Quoting: Stoney
I am still trying to find out how the commercial log cabin companies can pass energy compliance with 6 inch walls.


It may have something to do with where, in what climate zone, the cabin is to be built. Using my cabin as above (which is located in a fairly severe high altitude climate zone) and plugging in the geographic data for Athens, GA the cabin will pass with 5 inch eastern white pine walls. Same building will not pass in Albany, NY, but it will pass in Richmond, VA. And so it goes as the climate zone changes. And that's with using Eastern White Pine which doesn't count for mass wall until 8 inch thickness is reached. See link for chart from the IECC. Also note the second attachment which is from the a log home builders assoc. It is basically the same chart but wirh sp.gr used instead of species.

Add in the attic or roof insulation variable, the floor, size, number and quality of windows and it's almost too much too comprehend. Hence the REScheck calculator.

So, as we have both already stated Stoney, one must check with their local code officials, one size does not fit all. Sorry if I sort of used a sledgehammer to illustrate the point in my original post on this. My mountain location was rather demanding when it came to the IECC.
log wall thickness & mass rating eligible
log wall thickness & mass rating eligible
logthermals004.pdfAttached file: same but with sp gr instead of species
 


Stoney
Member
# Posted: 25 Oct 2010 18:31
Reply 


I contacted Log home Builders.org and ask how a 6 inch log wall could pass energy codes and this was there reply.

"In Washington, an engineer can calculate the thermal mass of the wall (instead of the R-value of added insulation) in a heat loss analysis to bypass any insulation requirements the codes may require. Other areas may do it differently, but that's fairly common."

I must also add that they stated that they were not really keen on 6 inch walls either.

MtnDon, I appreciate your passion for your trade. My objection was that many readers here would have understood that a 6 inch log wall cabin could not be built. As you stated there are many variables to consider in the building process not only wall thickness.

I don't pretend to believe that my building would be a good fit for everyone. This is just a new alternative for some who may not be able to afford an expensive kit or prebuilt structure. A novice can get good results with minimal impact on their wallets.

Thank you for the chart. I have never seen this one before.

toyota_mdt_tech
Member
# Posted: 26 Oct 2010 09:26
Reply 


I built a 8X12 log cabin tool shed year ago, and that thing woudl hold heat forever and the largest log we had was maybe 8" (at the widest point) down to 6 inches.

Stoney
Member
# Posted: 26 Oct 2010 11:01
Reply 


You are thinking right along the lines that I have been thinking this morning. This is one of the variables that we mentioned earlier.
I compared the profile of an 8 inch log with the profile of a 6 in by 8 inch rectangular log and this is what I came up with.
I used an 8 inch log that I consider to be pretty common as to what people visualize when they think of log cabins. A pretty sizable log, assuming the log is the same diameter its full length.

The area of the profile for the 8 inch round log would be 50.24sq inches. This is the old Pi times the radius squared.

The area of the 6" by 8" log profile would be 48 sq inches. Length times width.

My conclusion would be that the rectangular log has just a little smaller mass than the 8 inch round log.
The rectangular log may be equal or better in performance because the joints between round logs are likely to be less than six inches.

If you can see an error in this conclusion please point this out.

MtnDon
Member
# Posted: 26 Oct 2010 11:40
Reply 


The REScheck program does not take the material in rounded faces of log walls into the calculations. It uses a squared off profile as illustrated in the image below. An engineer might take the entire mass of the wall into his calculations and certification, and might not. The engineer costs extra, REScheck is free.
logsections for REScheck
logsections for REScheck


MtnDon
Member
# Posted: 28 Oct 2010 11:47 - Edited by: MtnDon
Reply 


Here's a very interesting Log Wall Energy Study link

Back in 1981-82 the Bureau of Standards built size same size buildings using different materials and techniques. One used 7 inch square logs and another 2x4 stick construction with fiberglass insulated walls.

Test Results
During the three-week spring heating period, the log building
used 46% less heating energy than the insulated wood frame building.
During the eleven-week summer cooling period, the log building
used 24% less cooling energy than the insulated wood frame building.
During the fourteen-week winter heating period, the log building
and the insulated wood frame building used virtually the same
amounts of heating energy.
Log_Wall_Energy_Stud.pdfAttached file: Log Wall Energy Study (from link)
 


Stoney
Member
# Posted: 28 Oct 2010 12:58
Reply 


I have seen this one before, I just forgot where I found it.
Thanks for the link.

bugs
Member
# Posted: 28 Oct 2010 16:57
Reply 


Hi Stoney

Quite the design and great idea.

I remember staying at a friends log cabin that was built in a very similar way. The name "quarter log construction" comes to mind. The logs were cut into essentially the same "tongue and groove" system that you have done with the boards. I think it was considered almost a kit project.

Not trying to criticize but there has got to be something less than ideal about your set up that builders have to be careful of. It can't be perfect can it?!!!!! I am scratching my head on this one cause it sure looks like close to a perfect concept. Thought of off gassing glue. But that is no more an issue than any other type of building material these days. Expense? Nope, reasonably priced compared to other structures. What about shrinkage/cracking of the boards? Again it is probably better than other materials out there.

Just can't find anything really wrong with the whole idea. Well done. I also like the fact that the person in essence gets to create their own building "blocks" and can customize them as required by the plan.

fasenuff
Member
# Posted: 28 Oct 2010 18:12
Reply 


I think for a way of building a cabin that would be easy and stable it's a pretty good idea. Also since most are looking to build under the code radar anyway the whole wall density and R value thing is moot. Bravo for trying something new and thank you for sharing it.

Stoney
Member
# Posted: 28 Oct 2010 18:27
Reply 


Bugs,
I have never heard of "quarter log construction". I'm going to have to research that one and see what I can find.
One of the advantages of using Kiln Dried Lumber is that it eliminates most of the shrinkage and cracking. I allowed about a half inch above the door and window jack studs for shrinkage and the gaps are still there. It has been up now for about two and a half years and still there are no new cracks in the boards.
I made a deliberate attempt to make sure that I could get all of the materials locally. This is why I used construction adhesive for chinking. So far It has held up really well.
When the photo's were taken the chinking wasn't applied yet. I was waiting a couple weeks to see if it would shrink any.
We really did enjoy building this. It was a lot of fun since you could see the progress made everyday.

bugs
Member
# Posted: 28 Oct 2010 18:44
Reply 


Stoney

I will email my friend and get the low down on his family's cabin. He is a contractor by coincidence.

Wonder if the nails would start popping after a few dry/wet, winter summer cycles?

It would likely be slower than using plywood. But then with plywood there is all the insulation and finishing to do.

Stoney
Member
# Posted: 28 Oct 2010 19:08
Reply 


Bugs,
I would appreciate that information and am interested in how it compares this construction. I researched everything I could find when the idea first hit me and I couldn't find anything built this way with ordinary dimensional lumber.
We have some pretty extremes here in Tennessee with long spells in the summer of near 100 degrees and the winters into the teens. We really get the rains here in the winter/spring and still with all this I haven't seen any nail pops.
What really impressed me was the time and money I saved by not buying and installing exterior sheeting, siding, insulation, drywall and finishing. This adds up to quite a bit of savings.
I left the inside of my garage natural and I really like the way it looks. There were a few stains and writing on the wood that I removed with an orbital sander and that was it. It took all of five minutes.

bugs
Member
# Posted: 28 Oct 2010 19:48
Reply 


Stoney

We have +30C, rains and wet (at least this year +250% of normal), -40 C. At least it usually is a dry heat and cold... Almost makes it bearable!

Great about the nail pops. The money/time saved on siding, insulation and (if you like the wood look on the inside which I do) finishing the inside would be incredible. And you don't have to contend with the round logs on the inside for mounting cabinets or making interior walls.

Still can't come up with a negative.

bugs
Member
# Posted: 29 Oct 2010 10:10
Reply 


Hi Stoney

I found some photos of this cabin I mentioned.
cabin
cabin
corner
corner
cornerA
cornerA
inside
inside


MtnDon
Member
# Posted: 29 Oct 2010 10:44 - Edited by: MtnDon
Reply 


As the BNS tests indicated in some seasons the thermal mass really works for you, cutting energy use. Their test buildings indicated no loss, no gain in winter heating which is fine. What their tests did not cover is severe weather (cold or hot) occasional or weekend use. Thermal mass in this situation could work against you. We, like many, use our cabin for only 2 to 3 days at a time in winter, and maybe only every second or third weekend January through April. We, like many, do not leave the heat on in the winter when we are not there.

Our interior walls are a mixture of 5/8 drywall and 1x T&G pine. The floor is tile over cement board, some mass there. Ceiling is 1x T&G pine. Stick frame (2x6 on 24), insulated cavities. With both the wood stove and a propane heater going we can raise the interior temperature by about 20 degrees F per hour. The cabin is short sleeve comfy after a few hours but the tile floor takes at least 24 hours to be comfortable wearing only socks on my feet.

If the situation was the same but the cabin was of log construction or had some other form of thermal mass like a large masonry fireplace I do not think we would be comfortable inside as quickly. The mass has to be brought up to temperature before comfort sets in.

My point with this is just to toss yet another factor into the pool of items to be weighed when considering what to build. The usage pattern could be important. This would apply also for a weekend use cabin in a hot climate where A/C may be used for cooling.

Stoney
Member
# Posted: 29 Oct 2010 14:54
Reply 


Bugs,
This cabin sure has the same look as mine. I did notice some differences. The logs appear to be much thinner than mine, maybe siding, I can't be sure by the photos. They also seem less than eight inches tall because there are more than 13 courses of logs. It still makes a great looking building. I really like the interior color.
Thank you for sending the photo's.

bugs
Member
# Posted: 3 Nov 2010 08:14 - Edited by: bugs
Reply 


Hi Stoney

Here is the link to the company that I was talking about. My friend said they mill the logs into 3x6 (one groove) or 4x8 (2 grooves).

http://www.classiccedarlog.ca/products.htm

Your system is similar but different.

bugs

Stoney
Member
# Posted: 3 Nov 2010 09:47
Reply 


Hi Bugs,
Thank you for the link. I thought that the logs were thinner than mine by the earlier photo's. The finished look is nearly the same. Price wise, I think that I have the edge. The also had an interesting link to energy efficiency.
Are you thinking about building one of my Lumber Log Structures on your property? It sure would look great by your pond.
Thanks again.

bugs
Member
# Posted: 3 Nov 2010 10:15
Reply 


Hi Stoney

I hope our building project days are over for awhile. We want to sit back and just enjoy what we have. Maybe even do some real work and earn some money so we can pay of the last bit owing on the place just in case some adjacent land comes up for sale. We have this dread that the 160 acres to the south of us or the 80 acres to the west of us (the rest of the pond) are going to come up for sale and we will not be in a position to purchase.

Stoney
Member
# Posted: 3 Nov 2010 11:19
Reply 


Bugs,
I can understand completely. The 40 acres next to me may come available also and I sure would like to get it if possible.
Best of luck.

Artistic
Member
# Posted: 5 Nov 2010 19:02
Reply 


Stoney,

I think your concept is great, I ordered a set of plans off of Ebay today and I can't wait to start planning. Maybe I have missed it in discussions on here but have you tried the concept with wider material 2 x 10" or larger, just to get more vertical inches per constructed block?

Thanks,

Travis / Utah

Stoney
Member
# Posted: 6 Nov 2010 05:18
Reply 


Travis,
I have not talked about using larger lumber but I have mentioned smaller lumber for smaller buildings. The larger lumber would be just fine if you like that look. I used eight inch for two reasons. First, eight inch lumber resembles most other log kits and it takes 13 courses of logs to make eight feet. Secondly, ten inch lumber is more costly due to its larger size. I haven't worked out the actual cost for ten inch lumber to see if it would be cost effective with ten courses of logs. Everything should work pretty much the same. The look of the building is the only thing that would be altered.
Thanks for ordering. I will send it out Monday.

Xplorer
Member
# Posted: 10 Nov 2010 10:06
Reply 


Just ordered it myself. I think it would make an ideal garage for my place in the mountains.

pheasantplucker
Member
# Posted: 12 Nov 2010 23:16
Reply 


This is wonderful! So glad you shared your ideas with us here. Thank you!

mezmo
Member
# Posted: 28 Nov 2010 03:32
Reply 


Hi Stoney,

I think I saw your post of this on the T&TTT forum before.

Followed a link from the Country Plans forum to here and
rediscovered it.

Great idea, as others have said. Looks like a superior method
to the flat stack solid wall method.

But:
It shocked my memory into recalling that I had seen a similar
method being used by a cedar home manufacturer way back
in the late 1970s. I then recalled that it may have been the
Pan Abode company so I Googled them and came up with this:
http://www.panabodehomes.com/phoenix.php . This has 5 1x
cedar boards laminated into a 5x8 multi tongue & groove profile
that interlocks like your solution. But I'd swear I saw a 3 ply
set up like yours as well somewhere back then by a cedar home
manufacturer as well.

I'm not trying to rain on your parade but wanted to give a heads-up
in case you pursue it into a business idea. Check out patents and
design patents and such as well so you don't get caught up in that
kind of a problem.

I should think, though, that your jigs and use of off the shelf 2x
lumber should be enough uniqueness.

Anyway, be proud of your method and the building it gave you.
Both are tops!

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