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Author Topic: Wall Truss Systems For Enclosing Timber Frames  (Read 14122 times)

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Offline Jay C. White Cloud

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Wall Truss Systems For Enclosing Timber Frames
« on: December 08, 2012, 07:15:28 PM »
Hello Folks,

Well of all the things I can rattle on about in timber framing, I didn't think the first request would be for this topic, but I guess it makes good since.  We, as timber framers, don't have many choices for creating the "thermal and mechanical envelope," for our structures.  Infill methodolgy just is not in vogue here in North America, so the only choice, for a long time, has been to build a separate wall over the timber frame or use "stress skins."

"Wall truss systems," have been around since the late 70's early 80's.  You can even find articles on it in "Fine Home building."  The system is rather unique in many different ways.  If you use low grade rough lumber, you can save a considerable amount of money for their construction.  When you have chosen a style and thickness, instillation is pretty strait forward.  Where they really excell is the amount of insulation you can put in them, the advantage of using them as a "chase system," for electrical and plumbing, and the "architectural depth" they give a wall.  The latter benefit is considered to be a short coming by some, in so much, the thicker wall is not found pleasing to some.  Personally, and my experience has been, when you can offer a client the chance to have a "window seat" in every window in the house, or built in cabinets and storage where ever they want, they jump at the chance.

Well that starts it, I guess, lets see where it goes.

Regards,

Jay


"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Offline VictorH

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #1 on: December 08, 2012, 07:52:37 PM »
I guess I'll start with a question.  What exactly do you mean by a 'wall truss system'?  I googled it with a varied response.  Pictures would be great  ;D

Victor

Offline Jay C. White Cloud

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #2 on: December 08, 2012, 08:39:02 PM »
Hello folks,

A request was made to see photos,  I have some in the gallery that are just o.k. so I hope I can get a chance in the next few weeks to take more of the kind I do. Until then, for those that want to "bone up," on the concept, here are some links.  I'll answer questions as I can.

Regards,

Jay

http://www.greenbuildingadvisor.com/blogs/dept/musings/all-about-larsen-trusses

http://www.greenfret.com/house/larsen.html

http://www.builditsolar.com/Projects/SolarHomes/LarsenTruss/LarsenTruss.htm
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Offline WmFritz

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #3 on: December 08, 2012, 08:43:20 PM »
Check Jay's gallery here...



http://www.forestryforum.com/gallery/profile.php?uid=20330


Edit: Jay beat me to the draw ;D
~Bill

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Offline VictorH

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #4 on: December 08, 2012, 09:45:46 PM »
Thanks for all the links.  If I don't find a load of recycled styro I just might use the larson truss system.  I had planned to attach my sheetrock on the outside of the frame and one of the links did just that.  I wondered Jay, the pics in your gallery showed the truss system up before any interior sheathing.  How did you finish the interior of that frame?  Also what method is used to attach the trusses to the frame ie nails, screws or ?

Victor

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #5 on: December 08, 2012, 10:02:07 PM »
Thanks for starting this thread. You mentioned the trusses in another thread they seemed like something I wanted to know more about.  What methods are their for enclosing a house frame? 

I am aware of the SIPS panels which seems to be the predominate method I have seen.  I have also aware of people using 2x4 framing.  The Larson Truss is one I had not see before. 

During the course of this thread would you help point out pros and cons of each?

Offline Jim_Rogers

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #6 on: December 09, 2012, 10:18:31 AM »
Although I have never spoken, or written about the Larsen truss enclosure system, I did know about it.

And I have some details showing how it can be used to enclose a timber frame. I got these from a class I took at Heartwood school.

Here they are:

At the wall:



On the roof:



Jim Rogers

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Offline Jay C. White Cloud

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #7 on: December 09, 2012, 10:54:38 AM »
Leave it to Jim to be poignant and dead on with good guidance.  ;D   This speaks volumes to the "Wall Truss System,"  and even show the original form, this is the way they are built in Europe or with a true mortise and tenon joints between the "vertical cords," and the "spans."  Thanks so much for doing this Jim!

Regards,

Jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

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Offline Brian_Weekley

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #8 on: December 09, 2012, 12:00:48 PM »
I was not familar with this system--interesting read.  A few questions...

I've previously read that one of the concerns about stress skins or Sips is the potential for shear (when the outer layer of wood sandwiched between the foam tears away) by the weight of the siding attached (especially something like cement board).  This may be more of a concern if the Sip is cantilevered out in air and not sitting on a spline on the foundation.  While studying the Larsen trusses on the links above, it looks like sometimes the trusses are partially supported by the foundation and sometimes they are shown cantilevered out in space.  Of course, a horizontal truss is very strong (like an I-beam).  However, when placed vertically, they just don't look very strong to me.  I'm just wondering how strong is the siding plane held 12" out in air when it's attached to a grid held out by thin gussets?  Is there a similar shear concern with this system?

Vapor barrier, yes or no?  Most of the diagrams show an interior vapor barrier, but I seem to remember one of the articles I was reading recommended not to use a vapor barrier with this system. 

Even though the articles say tightly packed cellulose remains tight, I think I'd always be concerned about the insulation settling with time.  Also, any concern about rodents with loose cellulose in the walls (those little beasties seem to find a way)?
e aho laula

Offline Jim_Rogers

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #9 on: December 09, 2012, 01:10:17 PM »
A few questions...

I've previously read that one of the concerns about stress skins or Sips is the potential for shear (when the outer layer of wood sandwiched between the foam tears away) by the weight of the siding attached (especially something like cement board). 

First of all, have you ever seen this happen?

I went to a designers workshop held by a major sips manufacturer and they have a 10 guarantee on their product. And when a new employee researched the "call backs" that the company had gotten over the last 10 years 99.9% of the failure of their panels were because the windows and doors openings were not flashed right and allowed water to penetrate the panel which caused one skin to rot. So much so that they now provide flashing details to their installation manual.

They showed us slides of pictures of their failures. And the host stated that this would be the first company to show company failures as part of an educational workshop. They provided that the failure was because of incorrect installation of their panels, windows, and doors.

Learning from other people's mistakes is better then learning from your own....

And because their panels have never come apart as suggested above, they have increased their guarantee to 20 years.

If this "tear away" has happened it must have been with an inferior product many years ago. I'm not saying it hasn't happened, I'm just saying that I have never seen any evidence of it happening. Maybe I'm just living under a log, but I never have.

As far as sips panels go their is a schedule provided by the manufacturer that shows and requires that the panel is secured to the timber frame around the perimeter of the panel with the proper panel screws to hold or hang the panel on the frame. The only way an outer skin could pull off the foam would be if all these perimeter panel screws all failed at the same time. Along with the glue that binds the foam to the panel.

Proper installation of the panel is very important to ensure that these types of failures never happen.

Again, as I have mentioned I have never seen or heard of it ever happening.

Jim Rogers

PS. I haven't checked out any of the links provided above, yet.
Whatever you do, have fun doing it!
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Offline Jim_Rogers

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #10 on: December 09, 2012, 01:20:24 PM »
Vapor barrier, yes or no?  Most of the diagrams show an interior vapor barrier, but I seem to remember one of the articles I was reading recommended not to use a vapor barrier with this system. 

My picture shows a note that says "vapor barrier" on the outside of the frame behind the drywall before the Larsen truss system is attached to the frame.

Omitted for clarity of the picture/detail diagram.

So it says it should be there where it should be to prevent warm moist interior air from entering the wall installation cavity, cooling and condensing thus possibly causing rot or deceasing the insulation value.

Understanding vapor barriers and their locations is important to every type of enclosure system.

Jim Rogers
Whatever you do, have fun doing it!
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Offline Brian_Weekley

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #11 on: December 09, 2012, 02:13:52 PM »

First of all, have you ever seen this happen?


jim, Ive only read about this.  Ive never built with SIPs so Im just asking the question.

Heres the statement by Robert Riversong regarding vapor barriers I saw on the Builditsolar article:

I haven't used vapor barriers for 20 years.  On new construction, there's really no need and they can even be counterproductive by concentrating moisture problems at weaknesses in the VB.

Full-scale season-long tests at the Univ. of Ill. Building Science Department have demonstrated that of the total winter-season moisture accumulation in a typical wall section, 99% comes from exfiltration of moist air and 1% is due to diffusion through building materials.

If a house can breath (absorb and release moisture daily or seasonally), then vapor diffusion is not the problem as long as indoor moisture remains within normal limits

By the way, Builditsolar.com is one of my favorite sites (second only to Forestry Forum, of course  ;))Gary provides lots of great info and examples.

I found the answer to my pest questionguess I missed it the first read:

Insects and rodents don't like the boric acid used as fire retardant in the cellulose, so these two universal problems are minimized or eliminated.
e aho laula

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #12 on: December 09, 2012, 03:39:03 PM »
I don't personally have enough experience in enclosure systems or research.

It is something that I should "brush up" on.

I don't know what "exfiltration" means. I tried to look it up in an online dictionary and it didn't have a definition.

So I'll have to read up on it when I have time.

Those statements, such as:

"If a house can breath (absorb and release moisture daily or seasonally), then vapor diffusion is not the problem as long as indoor moisture remains within normal limits

And: "On new construction, there's really no need and they can even be counterproductive by concentrating moisture problems at weaknesses in the VB."

are to me making a lot of assumptions. And they almost sound like they are contradicting each other.

If it does concentrate moisture problems a the weaknesses in the VB then there is moisture that should be dealt with properly. The other statement says that there isn't any moisture. So, which is it? 

What if a house can't breath, then what?

What if indoor moisture is not within it's normal limits, then what?

Jim Rogers

PS. I don't know if there are answers to my questions or not.
And I really don't want to go down this road any further then to say you need to educate yourself as to what is proper for your frame enclosure in your area, climate, specific heating system/season. And to do what you think is best for you.
And not to put all your eggs in one basket. What I mean by that is, I would imagine that there are many opinions on what the right vapor barrier is. And who's to say which one is the right one.
Whatever you do, have fun doing it!
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Offline Jay C. White Cloud

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #13 on: December 09, 2012, 03:52:19 PM »
A few questions...

I've previously read that one of the concerns about stress skins or Sips is the potential for shear (when the outer layer of wood sandwiched between the foam tears away) by the weight of the siding attached (especially something like cement board).

While studying the Larsen trusses on the links above, it looks like sometimes the trusses are partially supported by the foundation and sometimes they are shown cantilevered out in space.  Of course, a horizontal truss is very strong (like an I-beam).  However, when placed vertically, they just don't look very strong to me.  I'm just wondering how strong is the siding plane held 12" out in air when it's attached to a grid held out by thin gussets?  Is there a similar shear concern with this system?

Vapor barrier, yes or no?  Most of the diagrams show an interior vapor barrier, but I seem to remember one of the articles I was reading recommended not to use a vapor barrier with this system. 

Even though the articles say tightly packed cellulose remains tight, I think I'd always be concerned about the insulation settling with time.  Also, any concern about rodents with loose cellulose in the walls (those little beasties seem to find a way)?

Hello Folks,

Thought, being Sunday and all, I would knock off early from milling, and respond to my new favorite place to write, so here goes.

Wall Truss System

This part will be short for now, but I'll try and answer what questions have come so far.  They need to be supported from below on a sill or "hung," from the rafter tails in a system know as a, "hung roof/wall assembly."

Someone asked about disadvantages?  Well I like them too much and will wait for others to try and find fault with them.  At that time, maybe I can address any shortcomings as there just aren't many.

Vapor Barriers

As off late, there has been much going on about "building sickness," the contributing factor to this of course has turned out to be mold related issues with some "out gassing," of day to day consumer products, (e.g. pillow-mattress stuffing, plastics, foam products, cleaning products, rugs and their padding, etc.)  What has seemed to exacerbate all of this is the "air tightness," of the home.

Within the last twenty-five years of building, "house wrap," and other well intended measures of sealing a home with vapor barriers, (i.e. cold climates-wrap with insulation next to heated space-warm climates-wrap the heated and cooled space, then insulate) has become the standard.  It is even required in many areas.  What is now being discovered, these are the major contributors to "building sickness."  All major (independent) studies are now showing we have "suffocated" our houses, and us in side them.

What do we do?  Well, current findings are showing you only need to mitigate heat loss through draft, not stop it all together.  There has to be trade offs.  We went from one extreme, (nothing,) to another, (air tight.)  Straw bale, Wattle and Daub, Clay and wood chip,  and Wet applied Mass Cellulose, are just some of the new methods to super insulate a structure.  You do not use house wrap with any of them if you did it would be catastrophic.  During speaking about timber framing and traditional building I picked up a trick from another speaker,  take a volunteer from the audience, and ask them to put on a "tyvek suit."  They aren't to do anything but sit there while the lecture continues, and when they start to feel uncomfortable, just raise there hand.  This usually takes less than fifteen to twenty minutes.  The inside of the suit has noticeable moisture; so much for "permeability."  The general consensus among traditional design/builders, do not use wraps and vapor barriers with traditional and/or organic insulation.

What about the "pink stuff?"  What was shared with me from a building scientist at the University of Minnesota a few decades back was this little interesting factoid. "Pink insulation," was developed in 1938 by accident, the military soon learned that it worked wonders for insulating refrigeration units, and "Owens-Corning" was off and running.  Now it is the dominate insulation still on the market.  However, most folks don't know that "what's good in the lab, ain't good in your homes walls."  Fact, the colder it gets, the less R factor glass insulation has, add a little humidity, (which is normal in a house - controllable in a lab), and you have no R factor at all!  All in all, minus the manufactures/insulation contractors hype and this is probably the worse insulation to ever use, even worse than asbestos, in many ways.

So my general advice to clients, (I make them sign a waver if they do otherwise), super insulated and don't use any kind of vapor barrier, except when designed for "wet" areas like bath rooms, near sinks or, of course, the roof, that we need to be 100% water proof.

Stress Skin Panels

Some of the many draw back to stress skins is not any worry about de-lamination or shearing off the frame they are attached to, this seldom happens and in the few cases I'm aware, of it was an instillation error, not something wrong with the stress skin panel.  The issue I have, (and have had since they showed up), is what they had been (and still are in some cases), made of, polystyrene. Another great product in the lab, but in "real life," oh my, look out.  We use to use the stuff to raise different types of ground dwelling Hymenoptera, (read ants and wasps.)  Even with the borates added to this stuff can (and does) attract these guys.  They just love your home to be theirs.  Remember they aren't eating it they are trying to nest in it, and if they can tolerated the borates long enough, (building up a layer of their own dead bodies in the wake, they can carve out a place to stay, and that is what the do.  We haven't even gotten into the other miscreants like mice, wood rats, red and flying squirrels that also seem to just love digging through the stuff just for fun!  How do I now this stuff?  I was a state licensed supervisor in nuisance wildlife and pest control for the state of Connecticut for almost 5 years.  I had a Zoology back ground and this license seem like a nice compliment to building timber frames.  Not to mention in the late eighties I could get $75.00 dollars for every "wee-beasty," with four legs I could catch.  On a good night that could be 30 animals!  :o

Now I do use stress skin, but only on roofs.  I also only use urethanes that have either completely out gassed or are guaranteed staff.  This is a good application for stress skin panels IMO.  In walls there detractor is, (besides the potential for "critter," invasions), the do not lend them selves to alteration or change.  If you want to run wiring or plumbing, they are simply not easy to work with.  Even in new construction, running wires is a real pain in the butt.


Regards,

Jay

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"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Offline jueston

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #14 on: December 09, 2012, 09:54:08 PM »
There are certain problems whenever talking about competing products like this, the biggest problem I find in almost every discussion is that peoples evidence comes from manufacturers, you don't have to long far to see the conflict of interest when an SIP manufacturer tells you how great EPS is.

One problem which any loose fill is faced with is settling, in an attic this is a small issue for 2 reasons, ease of access meaning if you are unhappy with it you can just climb up a ladder and fix it, and the second is that the settling is along the entire surface so there are no gaps created by the settling. EPS does not settle, once it's in place, it's there and it's not going to move. Filling in the gaps is not that difficult but I think most consumers don't want to hear "your new house is finished, we'll be back in a year to cut open your walls and re-insulate"

The other things that sticks out in my head is that doing residential remodeling I have torn open hundreds of walls around windows to find rotten framing and sheathing, but even when bad flashing has been left to rot for years usually its only in the first inch or 2 of framing, and its easy to cut out the damaged sections and sister those 2by's with another one and install new sheathing. I think if there was water permeation into a wall built like that, the rot could easily consume the entire 2*2 holding up the sheathing along with the plywood/osb straps which hold it to the house, which could make for a much more catastrophic failure, even though the remedy would be the same: remove siding, cut back sheathing, repair/remove/replace damaged framing, re-insulate, sheathing, siding. Obviously the answer to this is flash your windows correctly and then this wouldn't be an issue.

Lastly, I am not a huge believer in "R-Value" I realize its a scientific system and has a scientific basis, but when I see a igloo cooler a week after it was filled still with ice floating around in it, its just hard for me to believe that 3 inches of cellulose would have done the same, even though they have the same R-value.   Different systems insulate in different ways and its hard to compare them all with a measuring system which was added to code book 40 years ago.

Look at thermal images of any fluffy insulation compared to EPS and you will see that the heat goes through the drywall into the wall cavity and then goes up, gets trapped by the top plate and then works its way out of the house. EPS does not allow as much heat movement inside the wall. This problem is exacerbated by the tendency of loose fill to settle which means the heat works is way up until there is no insulation at the top of the wall cavity.

That being said, I'm not advertising EPS, every product has its pros and its cons.  And "greenness" is a complicated issue, using a natural building material might be better for the earth today, but having the best possible insulation is better in the long run. Making a really green house today and then tearing it down in 10 years is surely not more green then building a house out of oil consuming plastics if it was going to last 150 years.  Using Compact florescent bulbs is great while there in the socket, but not so great while its spilling mercury into our air. These are all different issues I'm just saying that we have to look at the big picture, and sometimes thats hard to do with limited information we are often given by manufacturers and the government that serves them.

Offline jueston

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #15 on: December 09, 2012, 10:06:43 PM »
Just a little info to back up what I was saying about R-value not being a great measurement:

Quote
In 1990 The University of Colorado School of Architecture and Planning put two insulations materials, cellulose wall spray and fiberglass. They built two identical structures. One with R-10 fiberglass in the walls and R-30 in the ceilings. The second structure utilized cellulose wall spray in the walls and loose-fill cellulose in the ceilings with identical R-values as the first structure.
 Another the R-value for the insulation materials was identical, their performance was varied. The cellulose insulation required 26.4% less energy to heat than the structure insulated with fiberglass.
 So as you can see, cellulose insulation, which is made from almost 85% recycled newspaper, can be a more eco-friendly and money saving choice, even compared to fiberglass options with the same R value.
 

Offline Jay C. White Cloud

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #16 on: December 09, 2012, 10:22:29 PM »
Hello Folks,

Jueston made some great correlation with his post and I would just like to add a bit more.  We are now learning that cellulose insulation works best when it is applied damp, (not necessarily with water but a binding agent kind'a like glue), and is sprayed into a wall cavity under pressure, before interior sheathing is applied.  This application methodology, nips the settling issue in the bud. Also, some of the new spray urethanes are going to be "soybean based," and when you combine a light coat of spray foam, (25 mm or less), then apply a "pressure" applied cellulose, you can get the best of both worlds.

With a "wall truss system," and a "breathing wall" applied under exterior siding, you get enough air circulation  to dry moisture that might accumulate in a wall.

Also, the way a "wall truss" is design, even if flashing is done poorly and you would have to replace something, it is considerably easier, than "stick construction."  The stock that supports the "wall truss" on the outside of my frames, (and the better systems  overseas), is a 50 mm x 75 mm member, larger than most "nominal" 2"x 4" wall studs.  The 50 mm x 50 mm member is on the inside of the frame, in most cases 250 mm to 350 mm away from the exterior.
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Offline timberwrestler

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #17 on: December 09, 2012, 10:43:16 PM »
We enclose our frames with all sorts of systems, but generally on the superinsulated spectrum.  There are so many methods and materials now, it is a little mind blowing.  I try to enclose our buildings with what best suits the client and the building.

I've never heard of a SIP shear failure from siding.  The brand we use are about 20 lb/in/in in shear.  The usual caveat of you get what you pay for always applies.  There are some scary SIP companies out there.

It is my understanding that the only way you can have an ant problem in your SIPS is by having a moisture problem.  Get rid of the moisture problem and the ants go away.  Most builders/siders are morons when it comes to flashing.  The details count.

Controlling air movement through a wall or roof assembly is infinitely more important than controlling vapor.  An enormous amount of water can deposited in bad places by air leaks.  The code is starting to catch on to this, particularly through the energy code.  Vapor barriers are only recommended in climates with more than 9000 heating degree days (as in the arctic).  Vapor retarders are generally code required, but that can be as simple as paint.  Mr Riversong is probably the most opinionated person I've ever met (and I mean that in a bad way in this case), but I'll agree with him here.

I want to point out as well that housewrap (that Jay was talking about) is not a vapor barrier.  It's generally to control air and bulk water leaks under the siding.  To confuse matters more the permeability of all of the different housewraps vary quite a bit.  I generally use felt paper, which is pretty amazing in that it changes permeability as it wets, and has a long track record.  There are times that I use housewrap though.

Lastly, and in response to the last email, there are different method of applying cellulose insulation.  Loose fill cellulose, like what you would find in an attic will settle, but that's not a problem in that case.  Loose fill blown into a wall, will also settle, leaving a gap at the top of the wall.  The reasons for this would be choosing the low bidder and/or incompetent installers.  Cellulose in a cavity should be dense-packed (at least 3 lb/ft3) or damp sprayed.  There's no settling, and no gaps.  It's the same you get what you pay for argument.  Any kind of batt insulation (fiberglass, cotton, wool) can't fit the space perfectly (around studs, wires, etc), so there's air movement (convection) in the stud cavity.  This isn't a problem with the R-value methodology, it's a problem with greed and marketing.  An R19 fiberglass wall generally averages R12 in a real world installation for the reasons above. 

As a side note to Jay's last comment: my installers are moving away from damp spray (and they only use water) to just dense-pack.  They very tightly staple a fabric to the interior of the wall, and pump cellulose in.  You need a big blower, much bigger than the Home Depot rental type.  You also can not damp spray cathedral ceilings or flat ceilings, it won't stick.  So you have to dense pack.  There's a good article in the newest JLC magazine written by my installers.  He made the cover.  Mainly you need to pick a subcontractor that takes pride in their job.   I think that would be the summary of my rant above.

Offline Jay C. White Cloud

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #18 on: December 09, 2012, 11:25:18 PM »
Hello Folks,

Great post "timberwrestler," I concur with just about everything you have written and you expanded well on some of my very same points.  The biggest choice is your "contractor/GC/timber wright/ect." Choose wisely, you do get what you pay for!

Thanks for the point about "felt paper."  I wish I could quote the research, but one of the building scientist that has publish in "fine home building," writing about "vapor barriers," and "house wraps," had to write a side bar comment to his article, because when asked what he would/does use.  He said "felt paper,"  and no "vapor barrier,"  If a system works, has a proven track record, (the others do not,) why change.  He has small building sitting in a field in Minnesota that have different configurations apply to them, his observations? A breathing wall with "felt paper," out performs all of the new concept house wraps and vapor barriers by far.

I agree mostly with all your observations about cellulose insulation.  I won't allow water binders to be used, application must be under pressure with glue type binder and or the system you described, which is probably the best if you can find a good HVAC contractor to do it, or do it yourself.  The only thing I would challenge you on is the binding agent pressure applied cellulose.  I have seen it applied to a flat over head ceiling in a warehouse 300 mm thick and it wasn't going anywhere!  I will note, finding that kind of HVAC contractor is not easy by a long shot, so in a since you are correct.
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Offline witterbound

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Re: Wall Truss Systems For Enclosing Timber Frames
« Reply #19 on: December 10, 2012, 08:29:59 AM »
We stick framed 2x6 walls around our frame, then had a company spray the expanding foam insulation.  My hunch is that the spray foam wasn't an option when the wall truss system was first envisioned. 


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