Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.
Log Home
Andy_6
Member Posts: 48
Thanks John. Thats about what I was figuring.
0
Comments
-
Looking for input about figuring out the load calculations for a log home with 18" logs. My wright soft program has a space to put in custom walls, however what is the average wall thickness of an 18" log wall 9'high along with the r-value. What has been has been you real life experiences been with the infiltration and load calcs. on log homes? This should be a fun project with radiant floor heating to be done with ground source heat pumps for both the radiant and A.C.0 -
Log Homes
Andy we have done about 10 log homes now and have 5 more quoted. The two types that we install in are Khuns Bros and Beaver Mountian both have an 8" log and I have been told by the manfactures that the logs are R-15. Haven't had any problems with the 10 so far! All houses are radiant and have used the 1 1/2" concrete poured method.
John Jr.0 -
Just goes to show ya...
Just when you think you know what you're doing, someone comes along and shows you that you don't know squat...
I've always looked at logs by their wood type species and the known R value per inch for that typical wood. In the case of an 8" pine log, it would have an R value of 8 in the fattest part and a ZERO in the skinniest part. So, 8 + 0 divided by two would be R-4. Now, your log home manufacturer is telling us that an 8" log has an R value of 15??? Do they know something that the scientist at N.I.S.T. and N.A.H.B. don't know?
R-15 eh...
I'm losing my faith in the typical R value based heat loss calculations faster and faster.
What's your take?
ME0 -
Mark, If an 8" log at its widest is R-8, how do you get R-0 at skinniest? Is the skinniest nothing, zero inches? Surely it must have some R-value. How do you put a nail in this skinny end?
I am thinking of building a log home and don't want any invisible log ends!!!! (ha ha ha)0 -
log R values
First - Mark E., what are you doing up so late. Don't you ever stop working!
Regarding R values of logs. The following comes out of Jim Cooper's book "Log Homes Made Easy". "A 6 inch thick white pine log wall has an R-value of 7.9; a western red cedar log boasts only R-6.5." He says that the value in logs is the thermal mass which offsets the poor insulating properties. He says a log home is a 'passive solar home'. I've also got to think that the construction and insulation between logs which affects infiltration has a lot to do with log construction as well.
See you in class!0 -
You tell me Ken...
What's the R value where the two logs meet. I realize there are different types of logs, but assuming worst case (common) scenario, what IS the R value where the two members meet?
Let's say I give you the benefit of the doubt, and assume you do an EXCELLENT job of chinking the logs together, and I give you an R 1 at the point of contact (generous at best), then the 8 plus 1 = 9, divided by 2 = Average R value of 4.5 Still not ANYWHERE near the R 15 the log home manufacture states, correct?
ME0 -
logs
Mark - you are correct if the logs are all stacked without chinking. If you use a Swedish cope to stack the logs together, the distance at the narrowest for an 8 inch log is about 6 inches, generally with some kind of insulation in between to compensate for irregularities in the coping process. Some manufacturers use tongue & groove with the same effect. However, I think you are correct in that one should take the R-value of a given thickness of wood and then calculate the average thickness to come up with a correct R-value.0 -
I'm...
grading your test Chuck:-)
I too have heard the fable about logs being flywheel mass intensive, and that doesn't hold water either, pardon the pun. They do have some thermal capicitance, but not much when compared to a cementitious material like bricks or cement.
It has been my experience that the biggest contributor to heat loss in log homes is the infiltration factor, that is a continuously changing factor. If the homeowner doesn't do a good job of keeping up with the shrinking logs, infiltration will eventually become to great to control and overcome.
I have a policy of asking the log home manufacturer or builder what the R value of the log wall assembly is as well as the expected A.C.H. for infiltration, and if possible, get it in writing. This way, if things go to heck in a hand basket, you have someone to point to in court, other than yourself.
ME
0 -
The log home in ACHR News
We are now about through the first winter on this home and the heating system is performing wonderfully. This was the home the John Hall did an article about that had panel rads on the second floor and Climate panel under hardwood on most of the first floor. Two temp system. If I recall correctly I used an r-value of 11 for the walls which are full round with a max diameter of 16". (basically figured a value of 1 per inch average) The thing that will jump out and bite you is the infiltration factor. I used a fairly low ACH of .7 on the heat loss for this home. I had spoken with the homeowners at length regarding the importance of sealing the place up and they did a fantastic job of chinking.
The original design called for a pair of rads in the main living area to supply btu's needed according to the load calc. The homeowners wanted to try it without them and I was curious as to how the home would heat also, so we made provisions for them and left them out. They still have not been installed. Between them they were to deliver about 9,000 btu's. The place heats like a dream without them. In fact I was able to drop the curve on both the high and the low temp circuits from what I had initially figured. I think that the climate panel is running at .6 and the rads are at 1.3 presently.
I'm with Mark as far as heat loss calcs. They generally err on the high side. I've never had one turn out to be inadequate. The key is of course, to do your calc carefully and accurately with log or any other type of structure.
Make sure that the home owners and/or the builder understand the importance of sealing up the envelope be it log, stick built, block, brick or steel construction.
PS: The HO just stopped by today with a couple questions about the Vitodens. In the course of our conversation I asked if he knew what his LP consumption was to date. From initial fire up (July) to now March 17th he said he has used 1225 gallons of gas. 5 people live in the home which features two jetted tubs and one of those human car wash showers. The Vito also drives the indirect.
1225 gallons at $1.25 / gallon = $1,531.25 divided by roughly 8.5 months in operation gives an average of $180.15 per month. Not too shabby for 3,100 sq ft of log house.0 -
Not an expert on R- value
Mark
That's why I have to rely on the information provided. I couldn't believe that the logs were R-15 either but the manufacture said they were and I made sure the homeowner got that information for me. Now when I did the design I used R-10 which after reading my post forgot to say (sorry). The homes that we do the smallest part of the wall is 6.5 and the logs lay flat on top of each other. They use a weather seal in between the logs which is like a tongue and grove.
John Jr.
0 -
I did
a heat loss on a log home recently. I found an R value of 1.3 per inch for pine in a book. My logs were 8 inch at the thickestpart. The logs wer flattened on the top and bottom so the thinnest part was 4 inches where they met the other logs. I came up with an R value of about 8. The HO did a blower door test and then re-did his chinking/caulking to improve his infiltration. Job is not finished so I have no reports on how well it will perform. WW
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Atta boy John...
Cause when their log home doesn't stay warm, are they going to call the log manufacturer? No, they're gonna call you! There IS more to it than meets the eye, and as previously stated, I have less and less faith in the old R value system, but from an 8 to a 15 is a bit of a stretch in my mind.
C.Y.A.
ME0 -
Even with small diameter logs
there is usually at least a 3" cope or gasketed joint at the log to log connection. Or else they would just roll off one another
The bigger challange is MAINTAINING this seal. As logs dry and shrink attention needs to be given to this gasketed or chinked joint! Some have merely a thin foam sill seal gasket at this connection!
The quality of log, fitting, and gasketing are the key!
Hense the infiltration load "changability"
I have seen logs split, when they dry, enough to see through! Part of the charm of log home construction, they tell me. Makes for a moving target for the heating contractor
Run a blower door on after completion, then again a year later!
My advise "hard to over radiate a log home" And consider supplemental as radiant floors alone, don't always get the loads.
hot rod
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
I am looking
at a job with radiant floors that was not warm enough in a log home. The contractor tried to make it with suspended tube radiant floors. In addition to the log walls they had log cathedral ceilings and trapezoidal glass in the gables. They could only reach 60 degrees and were spending 1000 per month in propane. There were multiple problems but I think they should start by installing joist trak extruded plates in the floors instead of just suspended tubes. The plates are a large initial investment, but they will pay you back with economy and comfort. WW
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Becareful Wayne
with those tall, glassous, log "fixers" You could very well be beyond the range of what radiant floor alone would do. Even with transfer plates. You basically run out of emmitter square footage! before you meet the load.
Run some numbers on that baby. Try the calcs with some higher infiltration numbers to cover your butt.
Tall, glass ended, log homes are the biggest challange I have faced. Heating wise Throw a bunch of can lights in that catherdal ceiling and things can really get weird
hot rod
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Don't forget the plumbing!
In the "real" log homes we've done, shrinkage is a concern. We've utilized fernco 3"x4" rubber couplings at the base of plumbing risers to accomodate the loss of height as the logs shrank. Almost 8" in two stories!
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
voids and R value
I remember once coming across a quote from a insulation contractor in a magazine. He said that a 5% void would reduce the overall surface insulation by 50%. Does anyone know where I can look to either prove or disprove it. It sounds surprising at first, but also somewhat believable. If the heat finds an easy path to cold, it should treat it like a highway.
thanks,
jerry
0 -
So if I get what you guys are saying, I will be lucky to see an R15 out of an 18" log wall system. And alot of infiltration.0 -
log home infiltration
We've done a number of log homes with a variety of joining methods. The more difficult one was built using trees (no kidding) instead of logs that were trimmed and more uniform. They drilled 1" holes through the trees to set them over re-bar, which kept them in place. Tapered foam chinking was driven into the space between the trees and then covered over with a cement-like flexable caulking. This was the home that settled quite a bit as the trees shrank. When I returned a year later, the plumbing stacks had all settled fairly dramatically and the 4x3 fernco couplings had taken most of the movement. The remainder of the downward force had caused the basement horizontal runs to lean the wrong direction. An adjustment of the fernco couplings corrected that issue. I used an R-8 value for the walls & the owners experienced no problems keeping warm.
The kit homes have had logs trimmed, squared where they meet with a tongue & groove type joint that is aided by rubber seals to either side. They weren't as thick as the tree-built home, so I used an R-1 to the inch of averaged thickness (an R-6). Same results.
So far we haven't had infiltration problems with any that we've worked on, but it's easy to see where shoddy or sloppy workmanship can have an adverse affect on issues like that.
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
I've seen/used telescoping coupling for log shrinkage some years ago. Very slick but dont' recall the inches they allow.0 -
For plumbing
There is a slip joint made for this purpose. Ferncos may not allow enough movement. I've seen 'em bilge our like the Michlin Man, and still the pipe ends touch. Matbe two stacked would allow more movement room.
The slip coupler we used looked like a PVC dresser coupling that you commonly see on underground lawn sprinkler repairs. Had O-ring inside to allow the pipe to slide without leaking. Not unlike the HW baseboard slip couplers!
It allowed about a foot of travel and kept the ends in perfect alignment. Can't recall the brand name.
I wonder that a 3" PVC dresser coupling with the nuts just hand tight would work. I have seen log homes settle a good 6". Need to leave some room for that movement
hot rod
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Mark, is of course
right on point.
Thermal mass is a bunch of smoke and mirrors. You cannot and will not heat a log home with "thermal mass." Huge thermal mass simply implies it will take longer to cool when the heat's off. Conversely however, it will take a long time to heat it up, when the heat's on!
Log homes are cool looking. But if energy efficiency is part of the desired end-result - log homes ain't the place to find it!
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
plates
In my locale jobs without plates can rarely pass muster in an insulated house. In a log home with cathederals? no way not going to cut it without plates. Even with plates that's probably going to be tuff. CYA on that quote buddy!! maybe you can garantee to give them 60F inside with a lower water temperature , but I'd be leary of telling them they can make it to 70 with plates alone.
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
Made that mistake once....
The first log home I worked on, the toilet flanges popped the fastening rings after only six months!! After using reducing fernco's (I thought I invented that!) we set up a measuring stick from the basement slab up through the open stair well and found the second floor level would vary by as much as 4 inches between winter and summer!!! I wouldn't have believed it if I did'nt see it but it makes perfect sense....
Cosmo Valavanis
Dependable PHC Inc0 -
I ran
a heat load and it should fly with plates. The HO had a blower door test and corrected some problems so the house is tight for now, but the suspended tubing is not cutting it. According to the wirsbo program the water would have to be at 190 in the floor to work without plates. Youch! that'sa hot. WW
To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"0 -
That sounds
Like a radiantec system. 190* water in suspended tube. HAR HAR HAR! you better have a hanger every 18" or it'll droop like a pot of overcooked spaghetti.0 -
PS
PS: The HO just stopped by today with a couple questions about the Vitodens. In the course of our conversation I asked if he knew what his LP consumption was to date. From initial fire up (July) to now March 17th he said he has used 1225 gallons of gas. 5 people live in the home which features two jetted tubs and one of those human car wash showers. The Vito also drives the indirect.
1225 gallons at $1.25 / gallon = $1,531.25 divided by roughly 8.5 months in operation gives an average of $180.15 per month. Not too shabby for 3,100 sq ft of log house.
0 -
With that much shrinkage are any of the windows breaking. What kind of logs are they. I don't want to have that issue in my new home.
Ken0 -
no broken windows
I have not seen broken windows, and this year the homeowner says that he has only seen a variation of only 1.5 inches, and this is over a distance of about 23'. The house was finished at the during the hottest days of summer. The wood was not treated outside because homeowner wanted a weathered look before sealing. The movement occured during last year's cold winter. Don't want to scare you off, ask an unbiased architecht for a better opinion.
Cosmo Valavanis
Dependable PHC Inc0
This discussion has been closed.
Categories
- All Categories
- 86.3K THE MAIN WALL
- 3.1K A-C, Heat Pumps & Refrigeration
- 53 Biomass
- 422 Carbon Monoxide Awareness
- 90 Chimneys & Flues
- 2K Domestic Hot Water
- 5.4K Gas Heating
- 100 Geothermal
- 156 Indoor-Air Quality
- 3.4K Oil Heating
- 63 Pipe Deterioration
- 916 Plumbing
- 6K Radiant Heating
- 381 Solar
- 14.9K Strictly Steam
- 3.3K Thermostats and Controls
- 54 Water Quality
- 41 Industry Classes
- 47 Job Opportunities
- 17 Recall Announcements