Foundation loading/total weight

[stockhatch]

Greetings all! Im a n00b here and have a couple few questions regarding Skip style cabins.

First, and most importantly, does anyone know of any states that DO NOT ALLOW this flavor of cabin construction? The whole method seems too simple and archaic to slide past the inspectors here. Is there any sort of national standard building code for cabins?

Secondly, these cabins(as all cabins) look pretty heavy, what kind of weight are we looking at when we start stacking 30'+ logs up 15 or 20 feet and then throw a huge, high pitch roof on them? Seems like a cinder block foundation wall would revert back to cinder, but Im not so learned in the art of load calculations and structural engineering...How does a log wall/roof system compare to a stick built structure of equal height/roof pitch regarding weight (Lets use 2x6 walls with sheetrock interior and vinyl siding for example)?

Also seems like two uprights(one on each end of the ridge pole, as seen in many of the student built examples) would have a very hard time supporting the wieght of these massive roofs...

Finally, since Im on the topic of roofs, and things falling down/caving in, what kind of windsheer loads can these structures hold up to? (I live in a hurricane zone)

I ask about all this for a few reasons. First, I dont want to have to convince the local inspectors how structurally sound these cabins are in my own words, because Im clueless in that regard. Secondly, I dont want my house to collapse on me(maybe this should be first on the list...) And finally, I dont want my house to collapse on me. Did I mention that I dont want my house to collapse on me?

TIA :D

[stockhatch]

No thoughts? I know I have seen an engineer or two running around here... :D

[Bronco]

I'm not a engineer, but I would rather be in a Skip built house in a 6.5 earthquake and a hurricane,then any stick built shack anytime. :D

[stockhatch]

Thanks for the reply, but can you give me any reasons why?

[loghomefun]

It's my understanding that every state allows log home construction. A skip style log home is just that, a LOG HOME. So unless you live someplace that tries to tell you log homes are against the law you should be ok.

And the method meets code. A home like http://www.loghomebuilders.org/log-homes-25.htm would have had to conform to the Uniform Building Code (UBC) because that is what most places used in the 1990s. Now a lot of places use the International Residential Code (IRC), and a Skip style log home can conform to that too.

If there was going to be a big earthquake, a title wave, a runaway mack truck, the big bad wolf, or Godzilla on the loose I would rather be safe inside a butt and pass log home than any where else (except for a bomb shelter). Once you understand the building process you understand the 'built in' strength, the inherent overbuilding within the system.

Doug

[stockhatch]

Excellent. Thank you for the information. One of the main things keeping me from flying out to take the class is fear of the code enforcement guys putting the nix on any cabin shennanegans before I even begin. I need to know that the information I get can actually put me in a house as opposed to just being material for water cooler conversations at work.

[rreidnauer]

I'm not an engineer either, but I'll toss in my two cents to clarify Jim's one liner.

The exterior wall and superstructure is extremely solid using Skip's technique. I recall in the class that Ellsworth mentioned there was a Skip style log cabin that was to be dismantled using a bulldozer. (I don't recall why) He said that it was extremely difficult to do so. It just didn't want to come apart. The secret is in the construction technique used. When finished, the walls really do become one piece that doesn't want to come apart for anything. Skip's three-story, 7000 s.f. log home is located within 1,000 yards of the epicenter of a 5.7 earthquake in 1996. There was no damage at all to the house.

As for the roof, (or any other part of the superstructure) collapse is pretty much impossible, as it uses similar assembly techniques like that of the walls, and it is built using a method I prefer and call 'structure-on-structure' construction, where you don't rely on fasteners to hold things up. Every piece of structure is set upon a piece of structure beneath it. It's then locked together using the Skip fastening technique.

Now, for hurricane/tornadic winds, there does exist the possibility of tearing off the roof (partly built as traditional construction) with it's larger than normal overhangs. You just have to be sure to increase the fasteners to meet the additional leverage gained by the large overhangs. (and meet the inspector's requirements :wink: )

Yes, these home are heavy, that's no secret. It is part of what makes them so energy efficient and solid. The footing area will typically be increased in size a bit to account for that. (your engineer will know how much) You mentioned seeing the roof (rather the ridge pole) being supported by two uprights (ridge pole support logs, or RPSL's) and concerned if it's enough. First, on all but the smallest homes, you'll find three RPSL's. I believe Skip's home has four if I recall correctly. With a proper footing, there is no problem handling the load. Also, the RPSL's only carry about a third of the roof load. (with each eves wall carrying the rest) Again, your engineer will determine the minimum requirements. The inspector doesn't know what is or isn't adequate. He just determines if it's built to the engineer's requirements.

[stockhatch]

Very good. These are all great answers and very informative. Heres another question to ponder: Is it possible to use a log that has some defect that cannot be seen upon inspection? Maybe some strange knot or disturbance in the grain of the wood that could make it weak?

[rreidnauer]

Well, there is a good chance that you're logs will require grading for a very modest fee. It will be up to the grader to decide what is usable, though, with the size of a log, an anomaly hidden within the log causing a problem would seem unlikely. (at least anything not large enough to show visible signs on the surface) A ten inch log even with a small defect is going to support far, far more than a 2x12 ever will.

Think of it this way. That tree had to be felled, loaded, transported, unloaded, moved around, lifted, secured, and just all around abused. After all that, and it's still in one piece, do you think something is going to happen with it just sitting there in the wall? Granted, you wouldn't want to use suspect logs for your RPSL's or ridge pole. You'd choose your best ones for those.

[stockhatch]

Good points! To be honest, I am excited about the prospect of building my own log home, I am just very skeptical that it can really be done so easily(theory-wise) I do realize that the physical part is a bit like work.

Hey, here is a question, Why not cut a semicircle notch into the end of the butting logs so that they meet the passing log in a tighter, prettier fashion? Could be a cosmetic enhancement possibly? Less chinking as well.

[Travis R]

Here is my answer to some of your questions with my opinion.

1. They have been doing these classes since 1965 (I think) and did not mention any statewide restrictions.

2. There are members that live in these homes in Florida and have no special problems with hurricanes. To ensure this you will need to come up with plans which are approved by an Engineer. He will decide if your home can withstand the wind load, but even then he won't tell you no. He is going to tell you what you need to change on your plans to meet code.

3. The notching you???re talking about is called "Canadian Chinless and Scandinavian Chinkless." In the class they will go over these types of construction. However, I believe that after you weigh the pros and cons you will decide against it (BY FAR!)

4. The reason Skip drove the dozer into his house was part of a bet (as told by Steve).

I can tell you that you will not be disappointed if you attend the class, and if you are they offer a full money back guarantee.

Travis R
Riverside, CA
Oct 7-8, 2006

[stockhatch]

Thanks Travis. I think I may not have explained about the notching well enough. Here is a diagram showing what I meant. The solid black lines show the current method, and the red dotted lines show the curved notch to make the logs butt up to each other tighter. Im not talking about notching the bottom of the logs to stack them chinkless style, and Im not talking about saddle notching and interlocking the ends that way, I just mean notching the butting ends so you dont have a giant hole in the corner to chink. PS, the drawing is crude at best but I hope you follow me now...

http://img.photobucket.com/albums/v46/stockhatch/notches.jpg

[Travis R]

OIC, I was actually thinking about that myself the other day. One theory is that the more of the inside of the log you have exposed (or compromised by cutting) you leave the log open to rot. However, that???s not really exposed. I suppose that you could do it, but it would be a lot of extra work. What does everyone else think?

Travis R.
Riverside, CA
Class of Oct 7-8, 2006

[seriousvol]

hey rod.where do you get your logs graded for a modest fee?400 bucks a day and 60 bucks an hour from tpi is the price they gave me.

[rreidnauer]

TPI would be who I'd be using -IF- I have to. $400 doesn't sound too bad, if that's what stands between receiving approval to build your home or not. I guess 'modest' is a relative term. :wink:

[Mark OBrien]

Thanks Travis. I think I may not have explained about the notching well enough. Here is a diagram showing what I meant. The solid black lines show the current method, and the red dotted lines show the curved notch to make the logs butt up to each other tighter. Im not talking about notching the bottom of the logs to stack them chinkless style, and Im not talking about saddle notching and interlocking the ends that way, I just mean notching the butting ends so you dont have a giant hole in the corner to chink. PS, the drawing is crude at best but I hope you follow me now...
A "Skip-style" log home is built with simplicity and strength in mind. The butt-and-pass is the most simple and strong method around. Just ask the Scandanavians who have this style buildings still around after hundreds of years. The scribing that you describe would be very labor intensive for no real gain and only a perceived cosmetic gain. If you like the look of that style and want to put in the extra work, knock yerself out! :lol: As for me, I really like the rustic simplicity and strength of the butt and pass method as taught by Ellsworth, Steve and Skip. Somebody told me about the KISS theory:
Keep
It
Simple
Stupid.
I thought they were calling me stupid, but the idea is to keep things simple. Also, I believe in that old axiom, "If it ain't broke, don't fix it!"

[seriousvol]

rod,that is $400 a day PLUS $60 an hour.marvin

[rreidnauer]

I wonder how long it takes to grade logs. Two hours per hundred? Eight hours? Days? Anyone here got the answer?

[stockhatch]

Well, there is some good news so far. I spoke with one of the county inspectors this morning, and they dont have any issues regarding cabins of any sort so long as the plans are engineered. They did tell me that the logs would need to be graded for use, but they didnt really know anything specific about that process. I guess the engineer would know more about the requirements for grading?

[adubar]

stockhatch,

The notching system you are considering looks more like a variation on the "butt" method. However, in most butt methods a vertical log is used at the corners to tie the butt logs to the corners and each other (some use sliding dovetails for this).

In your proposed notching case the joint would not give you any advantage mechanically (most likely it would be weaker???but good testing would be the only way to know for sure). Anytime you scribe (if you want to do it well and correctly) you add work to the equation. It is not an easy matter to progressively shape the cut to fit precisely the contours of the log it must mirror--it won't do to hack at it and "scoop-out??? a hollow and have done with it like many builders do!

One thing to keep in mind is that the ???pass??? log provides additional bearing area to the corners and strengthens them.
In most butt methods, the vertical log is used to provide the needed tie between the wall logs at the corner.



-A

[jeffro]

It looks to me like they are asking about the cut on the butt end of the logs, still using the Skip style butt and pass, however, cutting a rough "C" shape on the butt end rather than a straight cut so the log fits to the pass log a little closer and reduces the amount of insulation stuffing and reduces the size of the chinking.

I have thought about the same thing, glad I am not the only wandering thinker.

[adubar]

jeffro,

If you take look at the drawing again you'll see that all the ends are "flush." There appears to be no "pass," unless we want to measure in terms of milimeters?

stockhatch, did you mean to draw butt and pass or ends/sides flush ?

If you're looking at scribing and cutting just the butt ends and staying with the pass logs, then that would be an interesting proposition.
There is still the question about how well the cut sections would do with moisture, as the interrior is a bit more exposed than with a flush cut.

-A

[stockhatch]

Yeah sorry. Its a very poor illustration. I meant what Jeffro said :) Maintain the butt-pass method, but cut the end of the butting logs to more closely conform to the passing logs that they intersect.

[adubar]

I appologize for not reading more thoughfully and devling into the drawing.

I am the son of an Engineer and I was raised to look at drawings....


Now, it being the case that your method uses butt and pass and you only want to shape the ends, then the questions that need to be answered are,

Will it deal with moisture as well as a traditional butt & pass?
Do you gain anything structurally by using this additional technique?
Does the effort required to complete the notches justify any gain?

To my mind, an answer of "No" to any of these three quesitons relegates the additional technique to the relm of "Why use it?"


-A

[jeffro]

I don't see how it would vary much if any for moisture effects or structure capabilities, I think it is a pure cosmetic question.

[stockhatch]

Well, it would allow for more surface area on the end of the logs, which I guess could be more opportunity for moisture infiltration.Probably would be a ton of extra work too. Even so, I was curious whether anyone else had thought about/tried it. Just spewing random thoughts here.

[adubar]

jeffro,

I guess from a purely artisitic vantage point, you'd have to figure if you would ever need to chink betwen the cut end and the pass log. If you did, then the visual aspect will be relative: Do you like a half-moon shape with chinking next to it against the pass log or is a straighter line fine?
If you don't then you would have an interesting intersection between the logs---I'd just be worried about any changes in shape due changes in the logs. Will the connection remain tight? Or, will you end up with a gap between the logs at some point in time?



-A

[jeffro]

If I was doing this "C" shaped end cut, I would not spend enough time to get it to press together so tight that it did not need chinking, but would just fill in some of the large cap at the top and bottom of the butt log from the straight cut, making the chinking lines smaller.

I have no real intention of doing it, just trying to clear up what I thought the original question was about. Maybe if I did not have to work to pay to build the cabin, I might think about such extras as this one.

Jeff

[stockhatch]

I agree jeffro. This is something I will do on my second, larger home. Not on my first, learning one :D

[rreidnauer]

rod,that is $400 a day PLUS $60 an hour.marvin

I got an email from a fellow member about how long it takes to grade logs. Because I received it privately, I don't know if he/she wants their name associated with the message. I tried to email back asking to repost the email, but it got rejected, so if you don't want it up here, just PM me and I'll wipe it out.


At the sawmill I worked at in NoCal we had graders in the log yard who could go through 30-35 logs per hour. They had to see all sides of the logs and large logs are hard to turn quickly, especially when the grader was standing next to them. For grading house logs they were a bit quicker as the criteria for house logs were more lax than for timbers and lumber. A large knot doesn't affect a house log nearly as much as it would for dimension lumber.

[thepizzaguy]

Answering this question from my point of view, timer frame walls made of 2x6 will be 1/3 the weight of an 8 in log wall. Adding in the sheetrock might increase the weight enough to become heavier than a solid log wall. Vinyl siding is light enough that it's nearly a non factor. If also taken into account that the windows are the same in size and weight for both walls.

[ChainsawGrandpa]

I'm planning on 320,000 pounds for my house.

It weighs less than some because it is smaller,
but more than others as the logs are larger.

It weighs less than some because I am using less logs,
but more than others as I am using a masonry stove.

You get the idea. a geological enginner (or a quick glance
at the codes) should tell the soil load.

Divide the square feet of the foundation surface into the
weight and see if the planned structure fits below the
load bearing capabilities of the soil.

As for strength...

When I took the class, Skip mentioned the big crawler ("the one bigger than a D-8") could sit on the roof
without any problems. If you looked at his walls and
rafters, then did a few quick calculations you would see
this is entirely true.

As for heating mass...

My parents cabin used logs that are about 10". Those
walls were small, but it still took a while to get all that
mass warm. It also takes a while for all that mass to
cool-down. I'm planning on 22" lodgepole pines, and a
masonry heater that is about 4' x 13' x 32'. Should stay
warm for a while after the heat goes off.

There are more stories that exibit how strong these houses
are, and just how long all this mass hold heat.

G'pa