Author Topic: Mtn Cabin in Nicaragua  (Read 70366 times)

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Offline glenn kangiser

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Re: Mtn Cabin in Nicaragua
« Reply #75 on: January 28, 2012, 07:55:02 AM »
Great build and side info, Alex.  We have so many international friends and made 15 trips to Mexico so we enjoy all of the side topics too. 

I once paid a guard to watch my plane in Batopilas, Chih?,  MX.  A storm came in the night - he disappeared and I never did see him again.
"Always work from the general to the specific." J. Raabe

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Please put your area in your sig line so we can assist with location specific answers.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #76 on: January 30, 2012, 03:54:10 PM »
Good Monday...

Plywood on the deck.....got exterior after being told by half a dozen people including two local gringo builder types..."just do not have it here and if you get it it is phony".  This is stamped, etc. Just got to persevere...and not listen to all the old hands down here. Borated it and glued and nailed it down. A good feeling to stand on it and the view is even better. Dis not take a shot of a level, but it is dead level both ways. And just 1/2 inch out of true square.



An hour after we got the plywood down my framing lumber arrived...looks great.  This is kiln dried and planed a second time but no sanded. A upper class mill and a pain to deal with...but they delivered most of what they promised.  This is the wood that will show inside.



Bracing..lots of it and using compression and not fasteners (thanks Don P..I know you don't like piers and post, but this should hold).  Will put some in though..as soon as I get some 6 inch HDG ring nails in a couple of weeks.





Walls tomorrow.  Gets a bit more complicated with that, but gaining some confidence and the crew is good and listens.

Offline MountainDon

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Re: Mtn Cabin in Nicaragua
« Reply #77 on: January 30, 2012, 04:40:51 PM »
Those are some nice looking connections Alex.   :)
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #78 on: January 30, 2012, 05:45:57 PM »
Early on, I was introduced to the house in KY...about 2/3 way done that tilted on its posts and I quickly became a believer.  I happened across it by accident last week and must say I am amazed that it got that far without thought to stability.  I know I started on here with little thought as to that, but now I fear I am becoming compulsive about it. Noting bad about that though...having your house stand up is right important as a first step.. If the flooring is nailed poorly that is a shame, but not a disaster..  I got all of that on here, so it is a good deal you guys bring to amateurs.

Offline MountainDon

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Re: Mtn Cabin in Nicaragua
« Reply #79 on: January 30, 2012, 05:56:34 PM »
Alex, I just have to say I'm impressed; you saw, you listened/learned, you "did".  And right when it should be done, before the walls, etc are built. Excellent, excellent....  :) :)
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #80 on: January 31, 2012, 02:28:31 PM »

Do I need a top plate here in the front over the header which is 4x8..by 10 feet?

This is a ridge board and seems to me whatever needs supporting above this can be done by the header.


Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #81 on: January 31, 2012, 03:39:59 PM »
The horizontal plate creating a break all the way across the wall at the 8' level is incorrect, this is a weak hinge. Unless there is a level ceiling to support the horizontal break the studs should run uninterrupted from sole plate to roof.

When you say this is a ridge board, there are adequate rafter ties inside. In that case the header is supporting the glass and a bit of wall and overhang above.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #82 on: January 31, 2012, 04:31:13 PM »
You have any reference to how to attach stud to roof/rafter...looked hard but cannot find one.

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #83 on: January 31, 2012, 06:30:08 PM »
The way you have drawn is one way, an angled top plate under the rafter that the studs are nailed to.




this is another method, the horizontal top plates shown in these drawings are depicted here because those roofs did have a flat ceiling bracing that hinge;


...
But actually,  I wanted to back up before we go too far from the bracing yesterday. It is some of the best i've seen here, and your guys do nice work. This is mainly to keep refining that method since we are not only showing our projects we are trying to also keep evolving techniques. first the braces are probably strongest going from post to beam but that is probably quibbling. what caught my eye was the sharp point of the brace inserted into an acute cornered pocket in the post. Instead of the wood in that post pocket corner resisting the shove of the brace by taking the force in shear, that point is trying to split a chunk off the post. Don't fret, but for them that's doing in the future I took a couple of pics today.

This brace has a tennon on it, just mentally saw it off. Notice the 1/2" wide flat where I removed the point.

 
Here it is with the brace in pocket, squared end meeting square cornered notch in the post. It looks the same but this is taking the load in shear rather than in a splitting wedge type action.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #84 on: January 31, 2012, 07:25:59 PM »
Thanks for all the info on rafters, etc. i will likely have more questions after i read then and alsoin going over my plans it looks like we have an anomoly and I am trying to sort it out.

Boy...do you have sharp eyes. On the sharp edges on the braces.  Believe it or not, I saw the same thing as I was pondering notching to the post or butting to the beam. What happened was one of the guys took out all the wood above the notch (heaven knows why) so the brace was essentially just flat against wood. That being on a critically tall post, after a small rant,  I had them recut the brace and but it to the beam because we had no wood left. At that point it became obvious to me that is the way to go so the rest are done that way.  So, I have 4 of the first braces with the pointy ends and on close examination I too saw that could act like a chisel.  But even at that it is only 1 inch below the beam so movement will be limited.  I also plan on a 6 inch ring shank in each one. I am bracing all 3 rows across and 3 back (4 on the "tall" side).  I do not know if you can see from the pics but the back row of piers is connected directly to the beam so there is no post/moment arm above the pier.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #85 on: February 01, 2012, 03:34:31 AM »


Two things hit me on the lack of a plate in the front and back. 

One is the lack of any tie in of the walls that the top plates provide in the corners. That seems so important in reading about that particular part of the puzzle.

The other isn that in the front, that header is now supporting the weight of the front rafter  ( whatever is not picked up by the ridge board) and associated load across it, not just some incidental stuff.  Mine is a 4x 8 of guapinol which is a pretty stiff wood.  I guess the ridge is supposed to take all the load, but with the front rafter being short to accomodate the outriggers for the gable end overhang, not sure how that pans out and how to attach that "low" rafter, which will essentiall be a 2x6 on its side to the ridgeboard.

As you can tell, I am quickly over my head here and not too sure my guys have any answers.  Have asked my "designer" for some answers and be interesting to see what he says.  i don't have a lot of faith in his structural answers based on some of his suggestions.  I spent a lot of time on the deck and am now just catching up to this.

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #86 on: February 01, 2012, 06:37:08 PM »
You do lose that nice top plate corner weave with a cathedral ceiling, our eye candy comes at a price. If you are concerned wrap a metal strap around the corner and tie well to both walls.

A ridgeboard should not deliver any vertical load. The vertical load on the rafters should flow axially, down the length of the rafter, to the wall. The ridgeboard could be eliminated and the rafter top ends should be able to be simply butted together with no ridgeboard between them. If correctly built you could take a chainsaw and cut through the ridgeboard between every rafter pair and nothing would move A ridgeboard is simply there to give you something to nail the rafters to and space them correctly. Not to be confured with a ridgebeam, which does support the rafters, is sized to bear the load and delivers that roof load to the ridgebeam supports.

If the rafter is oriented the same way as all the others and simply dropped to allow lookouts to sit on top then the roof load is on the walls and the weight of the gable wall is all that is being supported by the header. If the end rafter is eliminated and there are just sloping plates atop the gable walls that the lookouts then sit on, then the header is taking the overhang plus half the way to the next inboard rafter plus the weight of the gable wall.

For a lightweight purlin roof with a relatively small overhang, ~1', on the gable ends I run a typical common rafter and run the purlins out to form the overhang. I use boards to fill between the purlins from the first inboard rafter out past the edge of the overhang. When the entire overhang is boarded solid I snap the line for overhang edge and saw it all straight at once. I then screw thru each board from the top into a board below that forms the underside outer edge of the overhang.
« Last Edit: February 01, 2012, 07:02:08 PM by Don_P »

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #87 on: February 02, 2012, 03:44:16 AM »
Thanks. Your info and what you do on the overhang tops me off in that regard and I will now think about the options.  I lean towards your last one with the boards overhanging, especially since i have a light roof.  Something always seem a bit amiss about hanging that big heavy rafter on the end for what seems to be little purpose. I will use a cut down rafter for the end to minimize the weight on the header below, although I believe it is strong enough to take it.

i have to smile when I read you explanation on the ridgeboard. The board vs. beam thing was new to me as little as 4 months ago and was explained on here.  A lo tof the people I talk to who know at least something about building kind of do not believe it abput the board...this include a gringo guy who comes by to "help" ( and really disrupts the routine). He does know a lot about building...has done it in real life for money, but just purses his lips and gives small shakes of his head when i tell him this. Scary...but a good warning sign not to listen to his advice without vetting it very well.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #88 on: February 03, 2012, 05:01:45 AM »
We had some time today as a few critical pieces of wood for the top plate not delivered and so we had to wait (still waiting...you may not know it, but here, "manana" does not mean tomorrow...it means not today)

Tried a few sample of the overhang. For one we nailed 1x6 rough cuts to 1 inch boards set at the position of the end and first inside rafters to simulate overhang just with the boards overhanging like the purlin extensions as Don described in his last post (last para). At 2 feet seemed OK, but at 3 is a bit floppy.  I think we will use five 2 x 4s (mine are actually 21/2 x 41/2) as outriggers and attach the 1x 6s across them rather than just have them stick out like an extension of the purlins. at three feet, that seems to be sturdy even at three feet. Means notching the end rafter two inches..it is a 2x10 for the 2x4s.  May also run the top plate out three feet and then we can attach the  lower end of the overhang to that. Need to see how that looks and how much we need it when this is assembled.
« Last Edit: February 03, 2012, 06:56:52 AM by alextrent »

Offline UK4X4

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Re: Mtn Cabin in Nicaragua
« Reply #89 on: February 03, 2012, 05:09:28 AM »
add some posts to the outer edges and cover the deck for those tropical rainy afternoons !

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #90 on: February 03, 2012, 07:47:58 AM »
My header in the front is 10' to cover the opening in the 22' wall. So I have enough area to sit under cover and still be pretty close to outside. The deck is only 8 feet and 5 of that is uncovered to let me gaze ta the stars.

On that note...do I need two vs. a single jack stud per side to support the 4 x 8 x10 header or is one safe?

Also, I am rethinking my big overhang. Was three feet, now at two. Overhangs are parallel to the prevailing and storm winds but still catch some. I's rather go to 12 than have trouble. Thoughts?

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #91 on: February 03, 2012, 03:58:21 PM »
I like 2'. Good thought, yes the header at that length needs double jacks.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #92 on: February 09, 2012, 03:02:55 PM »
No new pics up yet  but here is an update.

Wall went up fine. After some trauma with one of my wood suppliers (the expensive one) where they could not supply most of what  ordered and the hardest stuff to replace and would delay the project three weeks with the crew sitting on their hands, I got it.  Had to make some compromises. But will work around them.

My crew is doing a good job but has some shortcomings on the knowledge front...but maybe not much worse than many others in USA as well.  They are aghast that I do not use screws, they want to put four nails where you need two and if it ain't 16d it is suspect.

They also do some really dumb things that they know better about and so need to by with them and watching all the time. They put the sill plate in back of the double joist (caught that), but they knew to put the double in, and asked specific questions about where, etc. That kind of puts you to sleep on watching.

Come roofing time, I was nervous. Read up on the rafter stuff a lot and asked questions here. good thing...they could do it if left to their own devices but would be a mess. We spent one whole day getting the two back rafters up.  Granted they rare complicated by the fact that they run up from the floor and the joists lay on them and are cut into a few.  Next day e checked all the work and was fine and after another 2 hours with the third rafter, and some desperation lessons from me based on my online "learning" over the past 3 nights, it clicked and got almost all done today.

Their two biggest revelations were that the way to calculate and mark a rafter actually works.

The other is that he ridgeboard does not need support when the rafter are in place.  My crew leader had the light come on when we place about the fifth rafter on the wall and naied it...then he dropped the ridgeboard end down and it wedged in tight against the other side. He said...this does not even need a nail!

Been a long three days, but working out OK...and they are happy to learn.

I'll post pics tomorrow.

Offline Alan Gage

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Re: Mtn Cabin in Nicaragua
« Reply #93 on: February 09, 2012, 06:24:41 PM »
I'm impressed with how well you seem to be handling the crew. I'm in awe of anyone that can teach a bunch of people a new way to do something and keep them happy. Let alone show them how to measure and cut rafters when you've never done if before yourself. I think that would be a bit nerve racking.

Alan

Offline MountainDon

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Re: Mtn Cabin in Nicaragua
« Reply #94 on: February 09, 2012, 06:26:46 PM »
 [cool]  alex.

Just because something has been done and has not failed, doesn’t mean it is good design.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #95 on: February 10, 2012, 03:16:18 AM »
It helps that they are willing to learn....and I think they saw themselves in some trouble. People here re a bit different in that regard...if you show them you "know" they will listen.  I have been doing small stuff along with them to get their confidence.

I likely looked at every rafter cutting video on the web and read a dozen articles over the three preceeding days and the night after the first attempts..  We screwed up three at first but I have uses for them. The instructions were great...and while demanding, there are harder things. When we got the first one right we were home  free. These guys are also good enough carpenters that they now see how it works and can make small adjustments.

I am not a patient man, but this helps gain that.

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #96 on: February 10, 2012, 03:38:37 AM »
Oh but so worthwhile, you are dropping a mighty big pebble in the surrounding pond. This carpenter will become the "go to man", local carpenters will grab him to help them put a roof on and that knowledge will ripple. Good show  [cool]

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #97 on: February 10, 2012, 04:29:57 PM »
Yep, that is part of the reason for doing all this. Jobs and some better pay and some upgrading of skilled people.  We have a ton of NGOs here and some do a lot of good. On all the overhead is tremendous and I think this is a better way. The people are people..and this crew is kind of cool too.

On to the photo record.

The back wall...as you see the rafters on this are a bit more complicated by the studs .  I should have started them one in.  But it is strong and we got it done...half a day.



My local "boss" who watchs over stuff and gets me general labor, counseling one of my long time employees, Juan,  (also his Nephew). This is the second rafter day and you can see where we are. collar ties and all.



Stairs...good sturdy job,  and not too big a jump for the first and last step...I could swear we talked about calculating that in. No big deal.



This planer is worth its worth in gold and has made stuff look sooo much better.   Finished wood here is a relative term. We do every other board and then sand a bit on all. Really not all that much trouble...they like doing it.



Monday I get wood for rafter ties which I have to make from four 2x8s and a 2x4 sandwiched in between to make my span. I cannot believe it will not sag.  11 foot 2x8s with a 8 foot 2x4 to help sister them.  If that does not work I will use a steel purlin instead of the 2x4.

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #98 on: February 10, 2012, 06:19:56 PM »
You've just encountered the next problems that early roof builders ran into. What to do to keep the bottom chord from sagging. What to do if you cannot make a one piece bottom chord.


You know the ridge is locked in place by the triangle formed but the bottom chord is long and sagging. If you throw a rope over the ridge, drop it to the center of the bottom chord and cinch it up it would take care of sagging. The rope is showing that this is a tension member. You can nail a 2x to the ridge, drop it to the ties, lift them to a stringline and nail that kingpost to the bottom chord.

For a discontinuous bottom chord you would calculate the rafter thrust and use enough nails on either side of the joint to counter that. If it'll sag, drop a kingpost (an old and more correct name was a kingrod truss).

This is a sketch of a kingpost truss with a discontinuous bottom chord;

The spline in this case went through the kingpost and then is pegged with an appropriate number of pegs on each side to resist the tension load.

The splined bottom chord from above is the rear one in this photo. The forward truss also has a discontinuous bottom chord but I bolted fish plates across the center in this one instead of using the spline.


Don't be afraid to experiment with ways to slide some hidden sheet metal across the joint and nail through it.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #99 on: February 11, 2012, 04:30:13 AM »
When you say sheet metal....what gauge would work?  I have space to hide it in between the 2x8s for that .  I could also bolt a metal plate across on the inside, but have resisted the bolts so far. If I do use a plate, or a metal purlin in there, how far on each side of the joint need it be. I have some extra big Simpson T's from the posts, and could cut the top off the leg.  Sturdy and holes already there on each side. But only 16 inches long  so 8  inches per side of the joint.

I have someone coming down next week. Will some kind of a connection strap that can be found at HD  work so i can nail it in across the splice? I saw reference to a joist hanger being used. My big lack of knowledge here is on how think it needs to be...the straps look thin to hold across the splice.
« Last Edit: February 11, 2012, 06:00:38 AM by alextrent »

 

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