Mtn Cabin in Nicaragua

Started by alex trent, November 24, 2011, 12:03:35 PM

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Don_P

This is another good link to bookmark, the AWC connections calc;
http://www.awc.org/calculators/connections/ccstyle.asp
It gives design values down to 20 guage steel.

Mainly where I was thinking of using it was if you do install a kingpost. It sounds like the ties will be 3 ply built up. if the kingpost is also a 3 ply assembly there are a couple of opportunities to reinforce the connection with some sheet metal T's slipped between plies and nailed into the joint.

Are all the ties just supporting their own weight or is there going to be some other load on them? Functionally they are another member that can be replaced by a rope, a tension member. To a large extent sag is a aesthetic issue rather than a functional one if there are no other loads being supported. The splice simply needs to be strong enough to restrain the thrust, this can all be done in wood, the rest is gravy.

alex trent

Be a while before I can get that AWC info figured out...but looks like a good reference as I always wonder about "how much will this hold".

My rafter ties are just that.  No other load.  I got the idea from the 20x30 little house plans I bought a while ago. Not to build that, but to see how stuff was done and what plans looked like.  A good investment.

I liked the look of this for my "woody' place and originally was going to do it also to not need collar ties as this looked like it did both.  as it turns out, I decided on the collar ties (lots of wind here coming in the front) and likely overbuilt them with 2x8s...but they look cool and cannot hurt.

The rafter ties are a different wood...Guapinol...with a dark red cast.  So will set off the other wood. Strong and hard and heavy. About 1.5x the cedro macho I am using for the other framing stuff.  I was promised 22 footers to go across and figured they would not sag. Now with a splice, I figure the weight of them adds to sag possibilities.  In between the two guapinol pieces will be an 8 foot 2x4 (2.5 x 4.5), nailed with 5 16ds on each side of the splice. I plan on putting them a 18 inches above the top plate just for "headroom".

If it sags I will experiment and I am a lot less worried about this than my other "urgent" requests for info as this can be fixed without a lot of mess, and as you say this will not affect structural intgerity.  It might even pull the walls together!! How long will I have to wait for the sag...a day or a month.



Don_P

I'd nail one together across the room and measure at midspan compared to at the walls. If that deflection is acceptable, pull down on it, if you have a problem with that even a piece of wire or rod from the ridge down will do the trick. If it was easy to deflect it will creep down faster than if it was stiffer. How long? Its dependent on the strength and stiffness... gravity wins when the ridge is on the ground  :).

Let's get an idea on the thrust load you're restraining if you haven't. What is the pitch and is it 20' wide?

alex trent

4/12

21 feet inside of wall to inside of wall (22 feet on outside of wall).

2x8s are 12 feet long so have a 1 foot angle cut there..she usually give me and extra 6 inches so likely have 18 inches to angle...which is marginal for any good.

Occurs to me as I am typing that the plan is to move up the rafter 18 inches up from the top plate so the anchor point is about 20 feet not 21 which in turn gives me more than a 2 foot angle cut...that seems like it will help. Makes me wonder if instead of the 2x4 in the center I should put a 2x8 piece  just 3 feet long across that angle. I do not have more than that to spare right now.

Don_P

this is what I'm visualizing


I'm coming up with around 1750 lbs of tension in the tie, try not to raise the bottom of it more than ~14" above the plate. I'd guess that in that wood the nails are good for 150 lbs each so a dozen or more on each tension connection... rafter to tie, tie to block, block to tie, tie to rafter. There is so much lap length this thing ain't sagging.

Edit; just checked the codebook on a raised tie, 20' wide bldg, 30 lb/sf roof load... 14 nails per connection. In our woods.


alex trent

Thanks....

Your white areas, if meant to be one of the 2x8s,is about half way in real life...you show it about 1/4. Or maybe I am just misreading he perspective. Here is a rough look



I will likely just set the tie on the top plate..no real need to lift it. Maybe when we get it in place might be a visual thing to move it up a foot, but not that likely.  Means i can nail it right to the plate as well as the rafter, which I like. Lowering it shortens the overlap area in the splice a bit, but I may also get close to 13 footers as they are not consistent in how much extra long they cut and she know I need length.

I will have some 6 inch nails...any benefit to using them to go through all three members in the tie along with the 16ds in each side?

Don_P

Sure, the 6's will make a double shear connection which is stronger and of course the lower the tie the stronger it is.

alex trent

Lots got done over the past few days and finally got some pics.

Decided to change the rafter tie design after all that discussion.  The wood was heavy..KD a 1x8"x12' was 130 lbs. Hard as a rock, which I take equates to strength.  So spliced one together...had enough for an 18 inch "translappe', and then put a 6 foot piece on each side. 36 naild total and will do a few more 20ds when they get here. No sag.



Rafters are a pain..came as 12 footers and  needed (and was promised) 13' for my overhang , but had to use these,.  Maybe just as well as the wind will be kinder to these. Going to use 2x8 for fascia so that will help a bit.



We had to apply borate when the wood was up...on the deck we managed to treat all before. Works OK. OIf this works as advertised we will not have any insect problems. Using the high rate and ,y applier likes to see it run. The deck is now treated too!



Grade this wood for me.




Outlier up for the overhand....notched the front and back end rafters..2.5 inches in an 8" rafter...and the rafter is supported not just be the ridge board but studs every 2 feet.  Looks OK.


Don_P

Looking good!

Most of your wood looks to be select structural  ;D. The only thing that I see is there is a fair amount of figure. How does it split? In other words is it relatively straight grained? That is beautiful framing lumber. A few years ago I was repairing a 160 year old house. At the homeowners suggestion I had milled lumber from the same stand the original lumber had come from. The nice young man from the town came to tell me that I wouldn't be able to do that, Lord only knows what kind of lumber it might be... as I sat there on a pile of #1 and better  ::).

I suspect you could pull engines off those ties.

The gable overhangs look good, they are ok for low snow and moderate wind. I'd be tempted to scab on cantilevered rafter tails, that isn't much to keep the walls dry.


alex trent

#109
Yeah, I been contemplating extending the rafters.  We do have a lot of rain. Plus the look is better with some more overhang. Not much to be seen on that online. I do not want to sister as that will be seen on the inside. A lot of work. Still thinking on it.

Two things come to mind for about 18 inches additional. Got to support the rain gutter..seems like not too much..

1. Butt a piece onto the end using a dowel or all thread and some toe nails.  I tried this and seemed sturdy, but not very elegant

2. Notching  (not sure of the term) the existing 2x rafter overhang  so it is 1 inch wide  back to about 1" from the bird's mouth and fitting the addition to that with a corresponding "notch"so it overlaps the cut on the existing rafter.  Be an easy join with nails through each of the 1 inch parts  to join the pieces and maybe glue. Limitation is that I only have about 4 inches for the notch to work with.

As for the wood..if you recall, was not too long ago I was hunting for decent wood suppliers.  Finally hunted  some down. The wood in the upright shot is the Cedro macho..about same specs as SYP.  The other is the Guapinol   (Courbaril )  and it is about 50% more than SYP across the board. Dries and weathers to a rich reddish color.  Using it in a few places..top layer on the top plate, header and the rafter ties. Mostly planned it for looks, but now turns out the strength is a plus in those areas. Got to drill it when dried.

We also talked a lot about nails and I looked at a lot of test data.  Here they are lousy..so brought some in. 16d ring shank will not pull out after being driven 1/3 of the way with the Guapinol using a 2 foot crowbar.  I can attest to withdrawal strength on them.  Spirals, just barely pull out in the same "test".

alex trent

Decided to sister the rafters. 18 inches out Easiest. I looked and need an overhang. This is sound construction simply done. And quick as I need to keep it moving and this takes only half a day. Outside cannot see the sisters unless almost below.  Inside cannot see much.  Not the greatest visual option, but works here fine.

See my post in general setcion for another weird problem that cropped up today

alex trent

Update..

Things moving along..just the usual  (I guess) glitches here and there and working around them.

Front porch is decked and here are some shots and the wood decking which will turn deep red in about  a month. 







Makes me want to sit on it and have the morning coffee...will be ready for that is about a month.

Just got some good nails in so we are going around filling in places that we left a bit short initially.

We are ready to put up the roof tomorrow..purlins all up and all seems straight and square...last check on that in the AM before we start to put up the galvanized sheets. Going to screw in on the flats...man what a difference of opinion on that topic.

UK4X4

thats an awsome looking deck - when its fully dry add some oil and it will have a lovely deep shine,,,

how does you finish floor level look -alongside the deck level ?

tropical rains are thick- heavy and often horizontal !

shut the door and your humid city- leave open you need some vertical transition

alex trent

Floor inside is not down yet...will be a different wood/color.  There is no door!  Just a gate/screen and a drop down wood "blind" to cut wind and rain as needed.


alex trent

Got the roof on today.  Big step...been raining here in the "dry" season and my plywood subfloor is about shot.  Going to lay another layer on top..Anyway, that is no longer a problem.





Making th roof cap...no one sells the real thing so after much looking and exhporbitant quaotes from machine shops we bent some tin.



I have been stressed about the corners since we ballon  framed the front and back and took away the ties of the corner overlaps.  Added some straps on top to help (I guess)...cannot hurt anything.



Got my bathroom layied out..a bit unconventional, but it works with the guys to show them.



Some place else on this site people list their favorite tool  This is mine. Indispensable, as if a pic is worth 1,000 words...when you are short on nthe language, it is worth 10,000.



Alan Gage

Roofs are great.

Looking good!

Alan

alex trent

Thanks for the vote of confidence.

I will let you know after we get the first heavy rain. I was on the roof and the workers about screwing in straight and not to tight or too loose.  Lucky they did not throw me off...although they did bump the ladder pretty hard once.  They never screwed in on the flat, so thought another crazy gringo idea.

At least there is nothing below the steel for now, so if it leaks will be really apparent quickly and not do a lot of damage below.  Funny, I just threw the screws into my water collector (kind of) which is a 1/12 pitch an not a drop comes through.

Maybe I did too much research for this roof, because now I am crazed about all the possibilities for leaks. Or maybe I am just crazed, period!

alex trent

Can't upload to PB, so here is a verbal update.

Getting into the finish work inside and as we get further away from framing my guys shortcoming start to show.....lack of experience with doing stuff and sadly, most of all quality. Since we are working on a couple of things at a time, I have to dart around to observe all day. I am really not sure the work is or would be all that bad...maybe I am just not cut out to be a builder.

We are having some real winds from the NE (50 MPH gusts all day)..at the front of the house. It is not all closed in yet, but at least still standing...don't feel a thing.

Got a decent electrician to do the work. He is a bit fussy and wants me to look at every plug, but with the little I know about electricity he look OK. Since I have no real power it is kind of  an odd thing. Trying to get that figured out.  Solar is going to be a tough deal because of lots of clouds and tough position with trees. I have pared my power needs to a low level. Hoping I can stay with that...but even so, be a lot of battery charging with the small generator.  I got a 2600 watt Yamaha and works great for the build, but later on max 20 amps to recharge will be tough. I am doing the numbers now. Depends on how much time I am there and from the looks of things, may be more than I planned. Thought it was a 2 day/night a week thing, but now looks like 4 or so.

MountainDon

QuoteI got a 2600 watt Yamaha ....

That would be sufficient to run a 12 VDC 75 amp output Iota, like this one.    That could recharge 12 VDC batteries with up to a total amp-hour capacity of 750. Rule of thumb is max charge rate of C/10, where C= capacity of battery(s).  Strictly speaking you can go to C/5 until the battery is 85% charged. The Iota chargers have a three stage charge when used with their IQ4 optional accessory.  Iota chargers of the same model can also be stacked with another one of their accessories to enable doubling the charge. Can be handy at times.
Just because something has been done and has not failed, doesn't mean it is good design.

alex trent

Thanks...I did the calcs wrong. This info is a big relief as I do not want to get real big on the power or genset stuff.  i really want to keep this simple. This is all that I need to charge. I am starting with 12 v ...4 120 AH batteries.  Eveready Marine. I know not the best for this but here I can get them for $90 and given the cost/quality of other available batteries here...real deep cell... it makes sense. May go to six batteries.  But if I can use power discipline (ha..when have you heard that before)...I can do it nicely ..especially with this charger/gen set up.  I figured at that charge rate (max C/10, or maybe a bit more) I will have to run the generator 3-4 hours or so every two days. Likely will have to run it more, but that is my low power target to start.


glenn kangiser

I have used Marine "Deep Cycle" batteries before .  Better than auto but worse than golf cart, but I understand working with limited availability so as you say - it's a good start.  :)
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

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

alex trent

#121
Yeah, we got some no name 6v 120 AH batts here for 140 bucks vs the 12 v 120's for $90.  Hardly a comparison unless the no names are 3x as good which is  unlikely. I figure if I treat these good they might outlast me.

alex trent

#122
Getting close to the finish! Got the siding on..except for about 20 pieces that I am short...be a couple of weeks to get that...bad math.  Electric is about done and I am really glad I lucked into a good guy to do it..slow, but knows his stuff and doing a neat job.  Fired the plumber after 3 hours and he had to wait four hours for a ride down the mtn. Dangerous...wanted to drill blocking and joists and floor and then make pipe fit or drill some more. Will do it myself next week and have the builder help on a few things I have questions about.

Be about another two weeks to complete the inside..tile and floor.

Here are some pics of the outside.  I had the siding finished on the inside and left rough on the outside. Siding shows on the inside as there is no inside wall in most of the house. Looks great on inside  Pics to come. On the outside, I had second thoughts about the rough look, but now I am happy I stuck with that.  There is quite a bit of variation in the boards and when putting them up, look not so hot...but when up, the overall effect is what I wanted.








Panel box is in the back corner and will be in a small closet. Right below and outside will be battery box under the house.  I can get it inside with a 3 foot run to the inverter in the house and the charger will be there too. Pretty simple set up and I hope I can get by with it.  Power management will be the key.  We ran the line to the shed where then genset will be...about 70 feet and used 8 gauge wire and a plug into the 240 V generator outlet..... wire running to house inside PVC pipe. Powered up the house...next week we will try it on the inverter.



The two batteries I have used on the build got rough treatment...discharged way down many time  and charged with a poor charger, so I will use these in town to run the fans when the poser is off and get new ones that all match for the cabin, and a good charger...the Iota that Don pointed me to, looks like the ticket.

We had to fit in room for a small fridge. Was tough finding space but this works. Bumps into the shower and sticks out a bit off one back kitchen wall.  The corner here was a project for them to build...took half a day, but came out nice in both kitchen and shower sides. Helps define the kitchen space.


Don_P

Very  [cool], that is a beautiful building.

germanbird

I'm going to have to second Don_P.  Your place is turning out amazing.

You probably already covered this in earlier postings, but what is the climate like there?  Rainy season?  Colder spells?