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Timberframe based on Jack Sobon's house with 2 x 6 stud insulation envelope

Started by vtframer, February 02, 2013, 03:53:40 PM

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vtframer

Hi all - I live in VT and I'm new to this forum and I wanted to share with u all my plans that I've developed using Jack Sobon's 18x36 design as a baseline.  I've widened the house to 24' and added a 20'x18' bump-out out the north wall (36' side).  I've included a bunch of .jpgs of my sketchup drawing showing some isometric views plus close-ups of how I plan on attaching the 2x6 wall.

My basic plan is to attach a 2x6 -  24" OC wall to the outside of the frame and use dense-pack cellulose (blown in from the attic through each stud bay).  I'll use 1" thick rough saw boards for the outside sheathing and 5/8" sheet rock on the inside.  All the braces will be moved in 3/4" to the inside of the building so I can slip sheet rock behind them.


Foundation: since I'm adding 6" to the outside of the frame, I'll need a foundation that is 12" thick (sill and studs will be 15") ...so the sill will hang over the inside of the foundation by 3".  I'm toying with the idea of slip-forming my foundation from stone readily available all over my property, using the method developed by Helen and Scott Nearing (they wrote a book called "Living the Good Life").

So here are some pics of my design...I'm still adding some timbers (ie. roof rafters



 




 


Now with the studs added to the side...



 



 

...and some close ups



  

 

Dave Shepard

Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Jim_Rogers

Yes, welcome to the forum.

You can post the sketch-up plan in the "plans" section above if you want us/someone to have a closer look at it.

But you don't have to either.

Good luck with your project.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

MEMountainMan

Hi vtframer, Nice drawings! I think the idea of putting insulation in from the top is good but I know here in PA I'd get failed for no fire stops. Also I'd guess you'd have to attach the 2" x 6"s to the timber framing with "Teco" clips rather than just toe nailing them. What kind of R value are you trying to get from the insulation? More than R-19? Under the window sill studs will be an issue getting blown-in insulation in there. I'd love to see this when it's finished, really nice. Stay warm, Mark
LT15 30 feet cap., John Deere 850 tractor with a loader bucket and backhoe, John Deere 1010 dozer. some husky saws, a 5ft Logrite cant hook, a 3ft mill special, and a 30" hookaroon. A shop full of tools and 108 acres of trees to make things out of.  Done building homes for others now it's my turn

danreed76

VTframer:

Welcome to the forum!  Nice work on the drawing as well.

For sure, if you load up (or upload) a sketchup model of your frame you'll get lots of feedback.

As far as the building enclosure, I definitely recommend doing it in 2 sections so the plate in between can be a fire stop (ran into the same concern with the building dept. in GA).  Also, instead of bumping the braces in, you can put some 5/8" or 3/4" spacers between the frame and the stud wall, so you can slip the sheetrock in behind the timbers so you don't have to try to cut it in against the timbers, and the edges will stay hidden as the timbers move over time.

For the outside sheathing, you may want to consider using an insulating sheathing material.  The envelope performance rating skyrockets when you cover the outside of the studs (or wall trusses once Jay gets ahold of ya ;D), creating both a thermal break and a reflective layer.  Then you can put in wet-blown cellulose if you want to inside the stud cavities (but you may not need it).

Check out frwinks build https://forestryforum.com/board/index.php/topic,51272.msg740288.html#msg740288 some great stuff on insulated enclosures.

Regards,

Dan
Woodmizer LT40 Hydraulic with resaw attachment |  Kubota MX5200  | (late)1947 8N that I can't seem to let go.

jueston

it looks like a great plan.

filling from the top might cause some problems, like around windows and or if you have plumbing in exterior walls, the insulation might get caught up around that. wet blown in insulation might be better since its packed tighter and it doesn't settle.

welcome to the forum, we all look forward to seeing the progress as you more forward. good luck!

Mark Emig

Looks really nice. Have you considered foam insulation. I have a client I did a bunch of ironwork for that used foam in ther timberframe. The really nice part (besides no"sinking"of insulation over the years) is the foam really deadened noise. The house is near a road and you cannot hear much noise.  Hope you don't mind me butting my nose in.

shinnlinger

Thats basically my house.  Look in my gallery if you want. https://forestryforum.com/gallery/index.php?cat=16762

Works well and ALOT cheaper than SIPS and you don't need a crane.  I did buy a semi-load of 2" 4x8 used kiln foam (off a recommendation from this forum) and stuck up a continuous wrap of foam around studs filled with the pink vs blown in (cheaper)l.

Dave
Shinnlinger
Woodshop teacher, pasture raised chicken farmer
34 horse kubota L-2850, Turner Band Mill, '84 F-600,
living in self-built/milled timberframe home

shinnlinger

 Realized I was wall deficient in my album...  here you go....   
Unfortunately I can't find any pics of the hanging the foam panels over the pink stuff.  I went with a conventional 2x4 wall (a mistake, I wish I had done 2x6) had a commercial company stick in the pink stuff (cheaper than doing it yourself, better done and no itch in my underwear) and then tacked my used 4x8 panels over the studs on the inside, sealing the seams with cans of spray foam.  I then took long screws and screwed strapping to the studs thru the foam so I could hang drywall.

I had originally intended to go with straw bales so my posts sit 19 inches back from the edge of the floor but my walls are only 8 inches thick so the posts stick out in the room.  I made little connecting walls to tie the posts to the exterior walls that actually serve as very nice conduit to run plumbing and wire.  I also have no electrical outlets on the exterior wall as they are in these little connector walls

Look on the left in this pic and you can see the mini walls and outlets.
Shinnlinger
Woodshop teacher, pasture raised chicken farmer
34 horse kubota L-2850, Turner Band Mill, '84 F-600,
living in self-built/milled timberframe home

vtframer

shinnlinger - totally awesome!!!  u have a beautiful house and ur pics were real informing!

couple questions:

-where the studs 2x4 or 2x6?
-did u use a vapor barrier and/or house wrap?
-how did u attach the vertical siding to the wall?  did u use sheathing?
- did u use a timbered floor system or conventional?


Thanks!


shinnlinger

Thanks. It is a neat house that is inspiring to live in albeit far from done! 6 years and counting!

As I said in my post, 2x4 walls but I wish I had gone 2x6.  As the pics show, I used zip-wall sheathing which is also a vapor barrier knowing that a year (or more) later when I got around to siding, the tyvek would have blown off.   The siding is conventional B & B with the 1x10 boards nailed only on one side to allow drying/seasonal movement with the 1x4 battens centered nailed between the boards.  It has has held up really well with the big overhangs I had originally built to shelter the strawbales.  The other nice thing about the overhangs is that facing due south the winter solstice allows the sun to hit the back wall but the summer solstice barely hits the windowsill.

It is an open debate and time will tell whether I should have put the foam on the inside or outside for the dew-point issue.  I went inside for ease and will double up the foam upstairs and put up a reflective foil wrap over it on the inside to help keep the dew in the foam and in theory the zip-wall breathes but some say it would have been better to hang the foam on the outside. 

That said a sealed wall (spray foam between the foam panels and caulked to the floor) reflective vapor barrier and painted drywall should keep most moisture out of the walls. I taped the zip-wall, but if I knew I was getting the siding on quickly, I would forgo the tape (which would also save $$$) as that would allow better breathing as well.  A wall that is impervious as possible to moisture on the inside but breathes on the outside is a good thing IMO.

Dave
Shinnlinger
Woodshop teacher, pasture raised chicken farmer
34 horse kubota L-2850, Turner Band Mill, '84 F-600,
living in self-built/milled timberframe home

timberwrestler

VT,

It looks good.  I'm not sure if you have a building code where you're building, but that could change things a little bit.  The others are right, that technically you need fireblocking between floors in your stud walls.  However, dense-pack cellulose can act as a perfectly good fireblock, but it's been disallowed in the most recent code.  You can always run it by your inspector.  I use a Nu-Wool cellulose, and they can provide the paperwork to show that it's a fireblock.

I did a 2x6 wall outside my frame as well, with a 12" thick foundation wall.  But there are a few other options.  You can use a thinner wall with pilasters located at the post locations.  You could cantilever your floor system, and have it hold the stick walls (although it's tricky to insulate the bottom of the cantilever).  Or you could use a brick ledge type of ICF.

I'm a big fan of putting extra foam on the outside of the wall, and it may even be code required where you are.  The reason for putting it outside as opposed to inside is that it keeps the wall sheathing warmer, and pretty much eliminates the possibility of warm moist interior air condensing on the cold sheathing.  Shinn's method is fine as well, as long as the wall is vapor permeable to one side things will be OK.  It's worth noting that zip wall is not a vapor barrier, but it is an air barrier and weather barrier.  I've used zip wall for the same reason as Shinn--the clients knew they weren't going to side for a long time, and didn't want to look at tar paper.  It's also worth noting that interior poly vapor barriers are not required or recommended in all but the very coldest of the cold places.  And that foil/bubble radiant barriers are a huge scam.  If it sounds too good to be true, well...

www.uncarvedblockinc.com
www.facebook.com/uncarvedblockinc

vtframer

Hi all - What are your thoughts on the sill overhang on the inside of the foundation?  Given that half the sill is on the conrete, i thought it should be OK...I could go with a 12" foundation, but that seems excessive.

Thanks,
Mike

p.s. - I was having a hard time getting the picture to show up...it's in my album under house if it doesn't show up here...







 


beenthere

vtfarmer (Mike)
Good on the pic. 
And can always make good use of the "Preview" button to see just what your post will look like after clicking on Post.

The lower rim board below the bevel siding looks a bit suspicious, as it appears it will collect water running down the siding.
And not sure about the notch in the joist, as it may be a weak point.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Slab Slicer

Agree with bt on the rim board. Perhaps eliminating the 1" foam from behind it will tuck it back under the siding. Also, machining a "drip edge" along it's bottom edge will keep water running vertical, and not horizontal. Again, I agree with the notched joists also. Definite weak point. I'm accustom to standard stick framing, and use joist hangers. Don't think that will fit the look your going for.
2016 LT35HDG25, Kubota L2501 w/ FEL, Kubota BX1500 w/FEL and custom skidding rig, Stihl MS 500i, Stihl MS362-25", Stihl MS250-20", Stihl MS192-18",  2001 F250 SD 7.3, GMC Sierra Dually 6.0 gasser, Peaqua 16" 10K trailer, Sur-Trac 12' Dump Trailer 10K
Chuck

jueston

are you planning on your sill plate sitting directly on the concrete? I don't know about where you live, but where I live that would not be allowed, we would need some kind of treated member on top of the concrete and then the plate could sit on top of that.

vtframer

Thanks for the input guys...

- as far as notched joists, it's the standard method prescribed in the Sobon book....I assume it's OK and is a time-proven method (i hope! :-))

http://www.amazon.com/Build-Classic-Timber-Framed-House-Traditional/dp/0882668412

- i agree about the bottom trim piece, I was planning on using a flashing/drip-edge piece that will sit on top of the trim but behind the clapboards...that should take care of the water

- regarding the sill on the concrete, I'll use a foam barrier between the concrete and the sill

http://www.homedepot.ca/product/foamseal-sill-gasket-5-1-2-x-82-x-3-16/905956

...BUT, does anyone have thoughts on the overhang of the 8x9 on the interior of the foundation?  should i have pilasters beneath where the posts land?

thanks again :-)
mike

Dave Shepard

I don't like the overhang. The load path for the joist loading is not straight down. I think I would try to form a "brick ledge" on the outside of the concrete wall to support the 2x6 wall. I don't know how you are forming the concrete, but some of the ICFs that I have worked with have a brickledge form so you can have a 10" wall, then have the ledge only where you need it.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Jim_Rogers

The floor joist notch and pocket is clearly laid out in his book.

But I follow a standard rule of thumb about them when I design a floor system.



 

Recently, at the last guild conference in Burlington, VT, the engineers tested floor joist to sill beam joints, by pulling down on the floor joist and recording the stresses.

I believe all of the tests proved that the floor joist will fail before the joist pocket in the beam fails.

They haven't published the results of all the tests yet.

Jim Rogers

PS. If it was me, I'd move the outside wall out and make it hang half way off a piece of pressure treated stock.
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

witterbound


vtframer

I felt it would be more aesthetically pleasing to have a 1 1/2 story....having the bump-out be 2 stories would make the structure, over all, seem too boxy

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