Author Topic: Mtn Cabin in Nicaragua  (Read 69930 times)

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Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #25 on: December 16, 2011, 06:24:02 AM »
I am living in Granada now...30 minutes from the site and have cable internet.   Up on the mtn I have line of sight to a tower and get full phone bars.  Not all towers have 3G, so do not know what happens  when I get that there.

I moved for a little adventure and something different. I am consultant in Ag Marketing mainly and soon as I moved got a big assignment done mostly in Canada...so I do go back 6-8 times a year a couple of days each time.  Most of my work done here on the phone (Skype is great) and the computer. So the net is critical.

I have to say, more than just the work part, the internet has pretty much allowed me to start to build a house that is built right and deal with the very different issues I have here.  This site is the mainstay and the people who advise me on here have a great way of dealing with a host of things, from the very basic to the fairly complex. My knowledge base has gone from a 2 to a 6 from being on here and following up on other sites with the foundation info I get on here.  It is important and fun too to really know this stuff and why it works....or does not. This is the land of concrete houses, so knowing all this stuff is not just nice, it is really important to getting a place that is strong and will last. So, thanks to those who are helping...cannot tell you have much I appreciate it. Hopefully you will see the fruits of your labor as I post my build.  i am sure I will ask for more help..I am using what I learned on this first part.

Offline glenn kangiser

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Re: Mtn Cabin in Nicaragua
« Reply #26 on: December 16, 2011, 06:38:04 AM »
What nice words for the site John has provided for us all to learn from, alex.

I was early here from when it was a mostly text only with picture attachments through what it is now.  It has progressed, improved and great people have aggregated here like flies on flypaper.  Yup ... that's right.  Once they land here they are stuck here and we like it that way.  :)

Glad we have all made a site that is available so that we all can benefit from it.  Thanks to all who contribute or learn here.

 
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Offline John Raabe

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Re: Mtn Cabin in Nicaragua
« Reply #27 on: December 16, 2011, 06:58:13 AM »
Thanks to Glenn, the Dons, and many, many others who have shared their experience and ideas on this site! They have made this the valuable show, tell and ask place that it has become.

Best wishes to Alex and all the Santas out there.

Great house project you have going on down there. I will be visiting my brother in Costa Rica in January - Looking forward to the dry (and warm) season!
« Last Edit: December 16, 2011, 07:13:29 AM by John Raabe »
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Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #28 on: December 16, 2011, 09:06:43 AM »
A thought occurs to me as I read the kudos and "amazement" about my small place. Yep it does present some difficulties that many do not have. But, I see lots of builds on here that are every bit as challenging and adventuresome  as mine. Not sure 3 hours from HD or Lowes is much worse than here. I just needed a bit more in scourcing...which can be fun and rewarding. I see the same type roads. Guys (and gals) living on site in the wild while they build alone. Rookies building bigger, more complex things.  It is those things that have given me confidence to move ahead and just do it. so, I guess the point is just because you may be in W. (By God) Va, does not make it less of an adventure.  Some snow and freeze and likely more. Everyone deserves credit.


Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #29 on: December 16, 2011, 05:05:55 PM »
Advice on doing things in the soil..

I want to bury a water tank under the house..between two rows of piers.  Tank is designed to be buried.

My piers are 5'4" in rows 11' apart. Concrete and rebar.

Tank is 7'7' diameter, so if placed right in the middle of the rows and between the piers in a row will clear each of the surrounding piers by about 28 inches.

Is this OK, or will it measurable affect the pier stability?  Just one tank, so at most 4 of the 18 piers would be affected.

Seems OK to me as the tank is hard in the ground..filling the dug hole completely.

I have looked a lot online and cannot seem to uncover an answer.

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #30 on: December 16, 2011, 05:58:19 PM »
Just some real crude rules of thumb. The inverted cone of soil that the pier influences is sometimes drawn with 45degree sides. From the edge of the bottom of the excavation go out on the surface as far as the pier is deep. I'll bet those cones overlap or almost so. Dr Bonhoff has a paper on the net that has some heavy math for calculating the forces. I'm not really sure if it was a formula or an invitation to a Greek fraternity hazing.

This is assuming you are counting on the soil to stabilize the piers laterally, but other ways require more concrete. Block corners on the 4 corners of the building, running ~4' out each side of the corner, would go a long way to taking any lateral load from above and transmitting it to the ground without risking tipping piers over.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #31 on: December 17, 2011, 02:05:23 PM »
Before I get started with the beams...

This is what I plan to do on the splices

Right side (E., I guess)  between the two posts on the E. is open deck..to the left of that is the house...5' 41/2" OC...6x6 inch posts. On the deck end, the beams will cantilever 2 feet.

The two 2x10s for the beams are shown above the posts as they are laid out with the splices (vertical lines in the rectangles.... representing the beams).

Beams will be 2 2x10's..nailed together with 4" spirals ....two rows top and bottom...12 inches apart.  Plus a few in the middle as feels good to have a few more. 2x10's are are rough..so actually real  2x10 inch . SYP #2 grade equivalant



Set into posts notched  to accept them (10 x4" notch ) and nailed into posts with 5' spirals...5 per post.

Other topic from earlier...

On digging into the soil under the house between the piers for a water cistern...will not. Will dig outside the boundary of the house. Lets me put in bigger cistern and not worries about compromising piers.

I worked though the IRC formula for lateral movement of piers.  I did take remedial algebra (twice).  I came up with the number that all my columns together would cope with 12,600 pounds of lateral force.  Not knowing the real numbers for the moment arms of the posts and if my calculations are correct, hard to say what this means.  Looks low. Means my Jeep could pull it all over by attaching at the ground, not to mention 5 feet up on a post. Yes, this is bait for a smarter person to tell me what it means..
« Last Edit: December 18, 2011, 05:44:34 AM by alextrent »

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #32 on: December 19, 2011, 03:00:26 AM »
5'post?  25' tall building. But the post/ pier connection has zero moment capacity. The posts will just tip over and dump the building unless you take measures to prevent that, bracing.

Now you're back to the original problem, how much lateral overturning force are the bottoms of the posts putting on the piers. Just throwing numbers around, if the building is 20' tall and 30' long and the wind is putting out 12 lbs per square foot you'd be at 7,200 lbs positive pressure. The other side of the building has a suction pressure,  call it 15 psf, 9,000 lbs. Total 16,200 lbs. Divide by number of piers. This is also the force the bracing needs to resist. Long braces well attached to the building and low on the post will do the most good. Too short a brace that holds actually jacks the building up and puts large bending stress on the post.

I've pulled out tractor trailers, concrete trucks and delivery trucks, but they have wheels and are helping. The jeep is good for maybe a couple of K at best before it loses traction, I'll bet Mtn Don knows better. I used to keep the glovebox of my log skidding truck full of U joints, the guys at the driveshaft and transmission shop know me. There are times when you wish it hadn't hooked up  :D.
« Last Edit: December 19, 2011, 03:20:16 AM by Don_P »

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #33 on: December 19, 2011, 05:06:44 AM »
I see what you mean about the pier/post connection..the tie of the pier and post does not inspire confidence except on uplift and some straight lateral movement to keep post from sliding off the pier. Sure does not look like it will keep anything from tipping.

I am then assuming the building itself will do that when braced properly...and I plan to brace it strongly.  So the issue is will braces do it?

Here is a view of the building and post/piers.



Most forward posts under deck are 4'6" from ground..next set (first under house) 4 feet.

Building is 12 feet high at rooftop.

22x22 square

Wind is variable but seems to be mostly from west (left)

I plan to brace with 4x4 from post to post or post to beam both ways...trying to figure out which is best...sounds like longer (post to post) is better. So I go from top of one post to close to bottom of the other. Or from beam to post?

My only other option here is to run the concrete piers on the front two rows all the way up and skip the posts with those...so there is no connector to bend over.  Seems a better as with those the soil would help prevent tipping.   But my logic is off a lot on this stuff.

Or as I think about it...maybe I am better off doing it on the two back rows, which are shorter and easier to pour all the way up? Plus no moment arm to speak of to leverage it over N or S and to some degree E or W (but less)..  By my reckoning, not much could move N or S as the beams are hard tied to all the posts....so no matter how hard the wind blows N or S, the beams tie to the full concrete piers...they have to have lots of resistance to push back and not connectors....4 feet deep x 1 foot wide  on six piers. Not rock, but decent soil.

The question is must I do that if braced correctly as I would much rather not do that.

PS..He was helping me tow him up...all .8 liters of his engine. I though the first number had rubbed out and it was 2.8 or at least 1.8. Low range and second gear...about 3MPH but got there.

Was good PR for the jeep...very rare here and if it's not a Toyota they just smile.

We gotta prove ourselves. A lot of dumb gringos here. On the same note, I showed my builder guy the spiral nails and he was impressed....got it.  Was a bit of a test for him and he passed.
« Last Edit: December 19, 2011, 12:00:12 PM by alextrent »

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #34 on: December 19, 2011, 05:36:46 PM »
Quote
I see what you mean about the pier/post connection..the tie of the pier and post does not inspire confidence except on uplift and some straight lateral movement to keep post from sliding off the pier. Sure does not look like it will keep anything from tipping.

I am then assuming the building itself will do that when braced properly...and I plan to brace it strongly.  So the issue is will braces do it?

This is the part most people have a hard time wrapping their head around and the reason why the prescriptive code calls for a continuous footing and perimeter wall. The lateral forces on the building need to be safely transmitted to the ground. You are trying to replicate the bracing of those perimeter walls with a few diagonal braces. Trains do run across timber braced trestles, it can be done. You understand the force involved in a high wind is potentially in the thousands of pounds range, a couple of nails holding the braces aren't going to do much. Forced fits in compression do well.


 The style among folks here has largely been to put a post on the pier and run that up to the floor girders. This introduces another hinge where the post is connected to the pier. The post to pier connection is just keeping space aliens (or wind uplift) from stealing your house and keeping it from sliding off the piers. That connector cannot keep the post upright but you will brace the posts. The connector also cannot help keep the pier under the post upright if the building is dragging the pier sideways. The pier is unbraced by anything other than the soil.

 So yes, for a couple of reasons a full height concrete pier is better than a post connected to a pier.  A full height pier still needs bracing and it is harder to connect bracing to a concrete pier. Harder but certainly quite possible.  None of this is meant to alarm you, just to try to walk through my logic.

If the first 3 piers topped out at the same height you could half lap a couple of bays of pleasing X bracing that would run from pier to beam. Can't find the pic of my shop bracing, this is close;

edit, found it:

 From there back maybe switch to Y braces. I have nailed boards horizontally across Y braces and the post to help lock all the members together better.

PS ran across a scan of the wet service nail page from the NDS;


And just for fun, we talked about a hip roof on this awhile back. I've been working on some irregular hips lately, hips of dissimilar pitches. I worked on this calc some more to help with the trig (I took trig 3 times before they gave up  ;D). It also works for regular hips. This covers some of the angles and lengths but not all.
http://www.timbertoolbox.com/Calcs/irreghip.html
« Last Edit: December 19, 2011, 06:16:08 PM by Don_P »

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #35 on: December 20, 2011, 02:56:10 AM »
Pretty slick calculator.

Thanks on the "bracing and piers" stuff.  I am not alarmed...but certainly have a degree of caution. I am giving this lots of thought as to bracing and doing the piers right. It is a pretty small house...any bigger and not sure i would do it this way.

I take it X bracing top to bottom of beam/post is better than Y bracing.  Which ever one, I will be sure to set them in "tension" as shown..makes sense. As you may already know, there is a real dearth of information on bracing. Most has to do with decks and is sketchy.  A lot of it looks erroneous...or close to it.

I am going to set my beams on the  back row right on the piers with no posts, as those posts are very short anyway and posts for the rest.

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #36 on: December 20, 2011, 04:39:28 AM »
I think you understand but just a point of semantics for others reading. Braces work in compression, when the building moves and the angle between post and beam tries to close up the brace is wedged into its bearings tighter and prevents the angle from closing. Braces in tension are trying to resist that angle from opening... connectors will fail and the brace falls out, generally. Wood is a great compression member, steel is a better tension member, steel rods, straps, etc.

Most of the old pier and beam houses I've worked on tend to have one end very close to grade (often too close and rotting). This served as the "anchor" and was the primary bracing.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #37 on: December 20, 2011, 06:56:28 AM »
I do get it and semantics is important...compression it is.  Even seems logical, which you have to admit, not all of this is.

The nails chart is interesting to say the least...I have an assortment of MAZE spiral hardened nails coming.

Plus, now I have found a place to get dried wood. Going to visit today. Prices are about 20% higher than the green. and that means a lot here as the wood is expensive to start with...but seems a lot less trouble in the upper frame...the base up to joists is still to be green, air dried 6-7 weeks which my builder says is OK.
« Last Edit: December 20, 2011, 01:57:53 PM by alextrent »

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #38 on: December 21, 2011, 02:36:30 PM »
Lot of work done, but not much to show for it.

Got all the gravel, sand and concrete up the hill and wheeled into the site.  Finally found a guy with a truck that could take 6,000 lbs up the hill and make it in the narrow road.  Last guy could only take 3,000 and that was a strain. 

Checked out my "green" lumber I will use for the deck. Been at this mill 1 week, but sat in the forest rough chunks for a bit, so my mill lady says she thinks it is about 30-40 %. She seems to have her stuff together, so I think she may be right. I went around the yard and
hand weighed" other 2x6's to compare.  It is well stickered and in a great spot..out of sun but in the breeze.  Has about 3,000 lbs of chunks of wood on top so that should help.  In 3 weeks she give it a final trim and them I get it.  She has almost 2 feet on the long boards to cut off, so that will take care of most of the splits I see so far.

Got my upper frame lumber ordered and paying the freight for dry stuff...expensive!

Decided to add one 5 foot section (one row of piers) to the back of the house so now 27x22. Makes it a really different place with just the extra 5 feet.  I did this because I am feeling good about progress on wood and help...and not the least, figuring how to keep it all together.

Offline MountainDon

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Re: Mtn Cabin in Nicaragua
« Reply #39 on: December 21, 2011, 03:51:58 PM »
Quote
The jeep is good for maybe a couple of K at best before it loses traction, I'll bet Mtn Don knows better. I used to keep the glovebox of my log skidding truck full of U joints, the guys at the driveshaft and transmission shop know me. There are times when you wish it hadn't hooked up

The front driving axle u-joints are often the first to pop, especially when the front wheels are turned a fair amount one way or the other. An offroader with stock axles and a desire to get into the gnarly (or maybe out of the gnarly  ;D) is advised to carry a spare axle shaft or two (one for each side). That's easier than changing the u-joint in the field.

Dead pulling really tests your traction. Plain dirt doesn't offer much whereas Moab sandstone offers more than enough to break parts.
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 #40 on: December 21, 2011, 04:48:19 PM »
Question..

I was going to notch my 6x6 post to accept my 4x10 beam (rough so these are actual sizes). Hold in/on with small bolts. I read on here in a couple of places that the 2 inches on the post was marginal.

If I go back to on top, my choices are limited because of the rough lumber size.  Looks like AC6R does it. Price not too bad. But I see lateral load is (looks) low...about 1,000 lbs. To me that load seems important to deal with.  And to me this means that on a 5 pier unit, it only takes 5,000 lbs to push the beam back off the posts.

Not sure about straps...some heavy duty "T" ones available.  But says they only work (are rated) in pairs and with a 4 inch beam and a 6 inch post can't get that to work, unless I cut the top of the post back to 4 inches wide so the beam rest on this and not on 6 inches.

If I toe in 6 16d hardened nails per post/beam connection that gives me over 5,000 lbs shear. So maybe I am overthinking the connector use?

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #41 on: December 22, 2011, 03:10:51 AM »
You're understanding why the prescriptive code on foundations is what it is. I suspect the nail values you are using are the shear values for the nail itself, clamped in a steel vise. The true design value for the fastener in wood also factors in the density of the wood, checks the nail against multiple typical failure modes, chooses the weakest possibility, multiplies that by the toenail reduction factor and then arrives at a result that is probably alot closer to 100 lbs/nail... the awc connections calc, plug in SYP. I've usually notched out the 6x6 by the full 4x10 in your case, leaving a 2x6 "tenon" sticking up on the inside face that I nail or bolt to. The plies are face nailed one at a time as I build the beam in place.  You can put a T strap over the outside and large washers on the inside. The corner ends up with a 2x2 sticking up, not much. I've used a custom welded saddle on top of the post for a porch carry beam in hurricane country on one house, it carried the beam in a U shaped channel and had legs that went down the sides of the post, everything was bolted through, fairly spendy.

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #42 on: December 22, 2011, 03:32:31 AM »
I am getting a practical feel for the concept of the "weakest link".

Thanks..notches it is. No readily available fastener looks like the right thing for this.  My ends will not have double beams, so that helps on corners.  Just double 2x8 (rough) joists there on 11 foot span over a single 2x10..
« Last Edit: December 22, 2011, 07:08:27 AM by alextrent »

Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #43 on: December 22, 2011, 02:40:18 PM »
Getting close to having a place to store tools securely. Be a great help as loading and unloading is a pain..plus this will let me have a genset so will not have to lug the battery to the jeep.
Hopefully done next week...we have had a lot of rain for the start of the dry season.

As you see, rebar will keep them out even if they take the roof off. Strap hinges are secured with all- thread into the concrete and the door is tough stuff.  Blocks have rebar top to bottom, so tough to break through.  If they want to get in I guess they can, but if they have the tools to do it, likely will not want to.


Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #44 on: December 22, 2011, 06:24:19 PM »
Shoot! Ships passing in the night.
The designer of this plan I built a year or so ago used the root cellar as a large brace to resist the lateral loads then masonry piers for the rest.


Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #45 on: December 25, 2011, 10:07:10 AM »


Top plates supposed to be two 2x6s. I can get a 4x6 and am considering for the look.

Any reason not to use one piece as opposed to stacking two?

Offline MountainDon

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Re: Mtn Cabin in Nicaragua
« Reply #46 on: December 25, 2011, 10:19:52 AM »
Double 2x top plates form an overlapping interlock at the corners when installed properly and help tie the corners together.

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 #47 on: December 25, 2011, 11:16:40 AM »


Makes sense.

If I notch end of the 4x6s where they meet seems that does same thing.

But then I see another problem...splices for top plate will be over a single stud because there is no overlap as with 2x's.

I guess have to forgo the look for utility.

Offline Don_P

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Re: Mtn Cabin in Nicaragua
« Reply #48 on: December 25, 2011, 02:24:00 PM »
You could use a steel strap across the top of the 4x6's.

You were asking about bracing the foundation. A perimeter foundation does the best job there. Prescriptively, code also recognizes masonry piers with 4" or thicker "curtain walls" tied between them, the masonry curtain walls act as bracing for the piers. A Permanent Wood Foundation, is made up of treated plywood covering treated wall framing, the plywood is the lateral bracing in those foundations. In the above examples large areas of bracing planes do a very effective job. Many hands make light work, the large areas the lateral force is distributed over means the load per unit area in any one spot is fairly low.

When you start doing post and beam the framing is collecting load, transmitting it to a few discrete members and loading them more heavily. The loads on any one area, member, and connection become critical. First that connection must be capable of handling the loads imposed on it, when fewer hands are carrying the load each one becomes more critical. If one connection overloads and fails do all connections then overload or is there some redundancy?

Plywood makes good bracing, treated ply near the ground. It gives the opportunity to spread the load out over a bunch of nails. The plywood needs enough framing backing it up to prevent it's buckling under lateral load. At that point you're better with a PWF.

I've wondered about whether a block wall 5' horizontally, up the side, across the back and back down the first bay of the opposite side would work. The shortest wall and end is braced and also protects the underside from water.

If the bottom plate on top of the floor is a 4x6, running threaded rod from the foundation, through the floor and then the 4x6 and clamping all of that to the foundation would be a pretty rigid connection.


Offline alex trent

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Re: Mtn Cabin in Nicaragua
« Reply #49 on: December 30, 2011, 11:07:59 AM »
Small part of the whole thing got done today, but it will be a real time and work saver. Be able to securely store the tools at the site and not have to pack up every morning and pm.



And lug the batteries back to the house to charge...generator Monday.  This litgtle system works amazingly well but has limits that we need to get by before we start on the house.



 

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