NE Oregon 20 x 30+ 1.5 story

Started by CabinNick, June 01, 2015, 11:16:39 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Don_P

Cool, The short joist, I'm looking at is effectively bearing on the closet. The header joist then is not really point loading the 1st common joist so that is really more like a uniformly loaded joist and it has less tributary area than the other common long joists... it doesn't need to be any bigger than the other commons, they are the control.

Work one of them 3' oc x 19' span=57sf x 50 psf (40LL+10DL)=#2850 total load, #570 DL
http://www.timbertoolbox.com/Calcs/beamclc06b.htm
#2DF
The 5x12's look right  [cool]

Grade critically as you saw, these are long spans, take the time to get good stuff.
As my mason says, now all we lack is finishing  :D

Rys

 I'm trying to finalize my floor layout. One of the (many) issues I've been having is my stairs meeting code. Do you care to share what you came up with?
Our cabin will be a full time residence. Fitting everything in with good flow is quite a challenge!


ChugiakTinkerer

One degree of freedom in fitting stairs is the wall height.  Building with a 9' wall may allow the needed head clearance.
My cabin build thread: Alaskan remote 16x28 1.5 story

CabinNick

Don thanks for all your help!  I am feeling a little more confident with this build now that i am starting to figure out some of the details. 

Rys, I will post my stair details when I am at home with my files next.  I spent a LOT of time making it work but in a nutshell I had to raise the height of my walls to 11' 2" to provide the necessary headspace at the mid-landing, top surface of my loft floor is 9' 1 1/2", and stairs are 7 1/4" rise and 10 1/2" tread (without the overhang). 


Rys



CabinNick

Question on framing to support the beams for the 2nd floor.  I am leaning toward 6x12" beams spaced 48'' OC now.  I am planning on balloon framing 2x6 walls with studs spaced 16" OC.  With this large of beams, I assume I need to put a post in the wall under each beam instead of what you typically see people doing on this site where they cut a 2x6" ledger board into all of the studs to support the second floor?  This is what ffpara did on his Utah build: https://countryplans.com/smf/index.php?topic=14691.25

Don_P

Yup, post under them. When you point load something follow that load path all the way to the ground, so under the subfloor there needs to be a short post or some framing capable of taking the concentrated load as well, and that needs to be on top of foundation wall and sufficient footing.

Going OT a little bit, I bit my tongue when I saw it, one of those "look what fine work I've done" posts.  Now that we're on another thread with some time separation... a porch picture, they had piers and posts under the porch and then the porch posts on top didn't line up with the supports below at all. The concentrated load of the post supporting the roof out in the span of the beam supporting the floor load was effectively tripling the bending stress on those beams. Follow those concentrated loads carefully.

CabinNick

Has been a while since I posted.  Progress on cabin design/planning has came to a halt as project work on our land took priority.  It was a busy spring.  We hired a logger to select harvest about 60 of our 124 acres. They took around 40 log truck loads. The project went well, the remaining health trees should grow really well now and the forest will look good once all the vegetation grows back in the skid trails. 


We had the loggers hold back about 10,000 bdft of logs for us and a friend to mill into lumber (all of the logs with blue dots in the picture).  Next week we will be using a mobile sawmill to start milling the logs.  We will mill Douglas fir 6"x12"x20' beams for our loft floor, 6"x6" posts to support the beams, and the rest of the fir will be 2x8, 2x10, 2x12 for various things.  The ponderosa pine will all be milled into 1" stock for board and batten siding, exterior and interior trim, and interior shiplap. 


These are the logs that will be milled into the 20' 6"x12" beams - excited to see those exposed beams in the cabin next year!

We are renting an excavator to move the logs onto the mill and lift the beams off the mill, so we will also be digging our outhouse hole and doing some improvements to our road and cabin site.  Other than that, the only other movement toward building a cabin we plan for this year is hopefully contracting the foundation and septic this fall. 

MountainDon

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


Beavers

That's awesome...nothing cooler than building your own house from your own trees!

Don_P

Good deal, that's nice looking timber  :)

CabinNick

I am looking forward to making sawdust this weekend. There is something special about building with wood that you milled from your own property.  I will post pictures when we get done. 

OlJarhead

Ahhh yup :)  Speaking my language now :)

CabinNick

Well I am sore and tired but we pretty much got all of our swamping done over the last two weekends.  We rented a excavator last weekend to move logs and the 6"x12"x20' beams.  I had the excavator for 3 days and could put 24 hours on it.  We didn't use more than a few hours of time on the excavator during a day of milling, so I did all kinds of projects before and after we milled lumber each day.  Got the outhouse hole dug, put a fire truck passing lane in on our driveway (required by law), and piled brush from thinning.  Worked from 5am to 9pm each day. 

The milling went well.   For the beams we had 11, 21' Douglas Fir logs that ranged in diameter from 14-20".  The largest log calculated out around 2,300 pounds.  It was slow going due to the size of the logs and beams. We had to move the logs to the mill with the excavator, then use it to move the beams to the trailer and then unload the beams from the trailer.  We milled 12, 6"x12"x20' beams that will support the full loft, 6"x6" posts that will support the beams and will also be used for some exterior posts, a ton of 2x12,10,and8's, and 1x12 and 1x3 board and batten siding.  All in all we ended up milling about 5700 board feet of lumber.  Can't wait to see those beams up in the cabin!






OlJarhead

Looking great!  Looks like the sawyer knows his stuff too!

CabinNick

Thanks.  The beams turned out beautiful.  We have 4 stacks of lumber now ranging in length from 12' to 20' and all over 5 feet tall - people are starting to wonder if we are building a cabin or an apartment complex!

NathanS

That Doug Fir is beautiful. You must be really itching to build now.

Don_P

#92
A little grading stuff to think about as you pick and choose which timber to use where.
Look at the pic of the timbers on the trailer. You would need to look at all sides but from what I'm seeing, the top timber with the slightly waney edge, a little bark showing, that is the strongest timber showing, grain is straight and the wood is just about clear. That kind of timber goes to highest loads and/or longest spans.

Next timber down is showing cathedrals in the grain, there is grain runout, that is weaker. The near end is showing what looks like massed pitch on one of those cathedrals in the grain. Whenever you see massed pitch look for injury, that may be a split. If so cut that out and get beyond it. This timber and the one below it would be a grade or two below the top timber so shorter spans and/or lighter load places.

The bottom flat timber has 2 knots completely across the bottom edge that extend onto the faces. The way cross grain shrinks in length around knots means that edge will likely get shorter than the opposite edge meaning that timber will bow concave on the knot edge, that's why I called that the bottom edge... I would love to turn timbers like that with the knot edge up but then the crown would be wrong as it dries, we never get a break  :D. Anyway with those 3 fce knots that timber is effectively the width from top edge to knot tops, again shorter spans or lighter loads.  The timber under that one, the near knot in that edge looks like a well centered knot on that edge with intact fiber flowing around the knot, you can see that knot reappearing on the face right at the edge of the timber above in the neutral axis where stress is low that nice strap of wood flowing around the knot along that edge is good. The next knot up that timber is the controlling defect of what we can see, near midspan and a 2 face knot, that strap if good fiber is on only one side of that knot.

This is not criticism just recognition of the natural material we are working with. As I'm moving timbers around and looking through my pile that is the kind of thing that is rolling through my head. All depending on cut lengths I can often bump a timber up a grade by removing a defect with the length cuts. One thing I see often enough is trying to remove a knot or defect by putting a mortise there and removing that wood. That is a mistake. In that instance they are taking an already weaker section of wood and damaging it further, it is better to put the defect away from joinery and maintain as much fiber intact around it. If you can put a defect nearer but not at the end rather than say midspan of a bending member that is effectively bumping the grade up. Bending moment is greatest at midspan, shear is highest at the ends. Part of the challenge and reward of working with wood, it keeps you thinking the whole time. On a barn we were recently working on we had the catwalk joists in and were standing around at the end of the day jazzed... when I saw a gnarly 3 faced knot I had missed. Of course right on the highest stress joist, a 6x12 spanning 18' and supporting the stairs as well. At some point 5 of us had touched that joist, Murphy at his best. We made another one the next day and swapped out, it keeps one humble.

CabinNick

Excellent wood wisdom Don.  Thank you for sharing your knowledge. 

The Douglas Fir logs we cut into beams had more bow in them than I had hoped for - a couple of them had so much we barely got a 20' 6x12 out of them. 

dablack

Posts and beams look great!  The only big beams I used are 8x10 and 13' long.  I have four of those on the porch sitting on 8x8 posts.  Everyone loves the look of real solid wood and not some little 4x4s or fake posts or boxed beams (not that there is anything wrong with that).

Austin


OlJarhead

Quote from: CabinNick on June 26, 2018, 10:43:15 PM
Excellent wood wisdom Don.  Thank you for sharing your knowledge. 

The Douglas Fir logs we cut into beams had more bow in them than I had hoped for - a couple of them had so much we barely got a 20' 6x12 out of them.

We call that 'stress' and it can't be completely removed.  Watch those timbers as they dry as I would anticipate they will crown more than expected.  I always try to advise my customers to cut down stressed logs to reduce as much stress as possible -- for example, a 20 foot log with a bow in it might be two 10 footers with a lot less stress.

In the end, trees grow the way they grow and the sawyer can try to mill out some stress etc but in the end nature decides what it will do!  You will often get a lot better lumber for a good portable sawyer but that doesn't mean you will only get specials and number ones! :D

CabinNick

We finally finished milling 12,000 board feet of lumber (half for our cabin, half for a friend).  It is way to hot to work anymore; so back to preparing to submit plans for our building permit - hoping to submit in a couple weeks.  I have a contractor lined up to put in our foundation this fall, so need to get moving of finalizing plans.  Code compliance is a bit intimidating for a building newbie but I am enjoying learning all this stuff as I go. 

I have a few questions related to the foundation and also looking for anyone to tell me I am doing something wrong, stupid or against code! 



We are planning a 8" stew wall foundation on a 8x16" poured footing.  The cabin will be 20x34' with a 6x14' bump out for the main entrance/mudroom. 



Cross section of our stem wall.  Planning on using I-joist - 20' for the majority of the cabin and 26' span (supported by girder at 20') for the bump out.  I am meeting with the folks at the truss company next week to get the specs for the I-joists.



Cross section of the girder supporting the load bearing wall between the bump out and the main cabin.  Questions:  1) Can I put the post on top of the footers for the stem wall as I have them in the picture - this is how my current house was built.  Do I need to attach the post to the stem wall? 2) Will the I-joists be sufficient to transfer the load from the wall to the girder or will I need to use squash blocks?  Or is that something the truss company should spec out for me?



Cross section showing the two load bearing posts which transfer load from the second floor beams to a girder supported on two 16x16x8" footings.  I am a little confused on what needs to be done to transfer the load through the I-joist floor.  Can I just put a 6x6 directly under the post between the subfloor and girder? 

ChugiakTinkerer

Quote from: CabinNick on July 31, 2018, 10:34:47 PM
...
Cross section showing the two load bearing posts which transfer load from the second floor beams to a girder supported on two 16x16x8" footings.  I am a little confused on what needs to be done to transfer the load through the I-joist floor.  Can I just put a 6x6 directly under the post between the subfloor and girder?

That seems a little squirrelly to me.  Not based on code or anything, it just seems to have too many hinge points.  One wasteful way to transfer the load is to sister several i-joists together. 

Another alternative might be to stack a second girder on top of the first.  For the i-joists that tie in there use hanging brackets.  Probably overkill but it seems a lot closer to code-compliant.  Something like this...

My cabin build thread: Alaskan remote 16x28 1.5 story

Don_P

#98
The I joists at the girder are passing over a support, so all the way across the girder they need blocking between them, that is I think what is catching CT's eye. Then vertical grain, upright, blocks between girder and directly under the point loads from above, you can offset the roll blocking to let the squash blocks bear directly in line. To me those are squash blocks and are under every point load. From memory they are 1/8" longer than the I joist height, they take the point load. The I joist detail sheet will specify whether you need them at each joist around the perimeter, the rim board may be sufficient, ask for that while you're at the truss shop, they are generally online as well.

Web stiffeners are needed when there is load from above that you are accepting through the I joist. those are the pieces of ply attached to the webs, inside the flanges. The problem with just stacking I joists to take load is web crippling. Under significant load the webs begin to buckle into an S in section, so just like you see say on bridge I beams near supports you may need to locally stiffen the webs. Then as above, another way is to use squash blocks to bridge the load over and around the I joists.

That's a righteous snow load, you have planned this all out loadwise I hope.

CabinNick

The county accepted our plans yesterday and issued our building permit!!!!  Just a piece of paper, but an exciting milestone after several years of planning.  This is finally happening!   :D

Contractors are lined up to put foundation (poured stem wall) and septic in, in the next few weeks.  Hopefully we can get those two projects done before the weather turns.