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General Forestry => Timber Framing/Log construction => Topic started by: Jay C. White Cloud on December 08, 2012, 07:15:28 PM

Title: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud 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


Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: VictorH 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
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud 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
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: WmFritz 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
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: VictorH 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
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: samandothers 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?
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jim_Rogers 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:

(http://www.forestryforum.com/gallery/albums/userpics/10095/Enclosures-j.JPG)

On the roof:

(http://www.forestryforum.com/gallery/albums/userpics/10095/Enclosures-k.JPG)

Jim Rogers

Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud 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
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Brian_Weekley 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)?
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jim_Rogers 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.
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jim_Rogers 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
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Brian_Weekley on December 09, 2012, 02:13:52 PM

First of all, have you ever seen this happen?


jim, I’ve only read about this.  I’ve never built with SIPs so I’m just asking the question.

Here’s 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 question—guess 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.”
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jim_Rogers 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.
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud 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

Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: jueston 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 it’s 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 that’s hard to do with limited information we are often given by manufacturers and the government that serves them.
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: jueston 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.
 
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud 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.
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: timberwrestler 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.
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud 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.
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: witterbound 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. 
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 10, 2012, 10:04:26 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.

Hi Witterbound,

Actually many of the "wall truss systems," are attached to a timber frame, (or stand alone, depending on configuration,) then a thin layer of foam board is applied to the system from the outside.  Vertical and/or horizontal strapping is applied to create a "breathing wall," then from the inside, spray foam is applied and/or the dense pack cellulose system. 

Wall truss systems have been around for over 40 years, you just don't see them used much.  I think because of the DYI modality they have.  However they are in the mainstream and are commercially manufacture over seas, from what I have been told. (can't find a web sit yet, but I'm looking).  So they probably have been here before the foam.

Regards,

Jay
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: frwinks on December 10, 2012, 10:39:38 AM
Great system, any idea how much wood is used in the process?  For me the whole thing about wrapping a TF with another "structure" (be it SIPS, stick, truss) is way too backwards.  Two structures just in the name of having the timbers fully exposed to the interior?  say_what 
I cringe everytime I think about how much 2x4 material went into my place, such a redundant system.  Wish I pushed a little harder with our Peng and went with my original plan of 2x4 horizontal nailers 24" OC.

Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 10, 2012, 11:14:21 AM
Hi Frwinks,

Being a traditional builder, in the past, I thought when it comes to not using an "infill system," for timber frames, it might be foolish.  It was pointed out to me, many years ago, that times change and with them systems adapt.  What they went on to explain was if you are building a traditional building to be lived in the way or forebears did, or as an example, then build it that way.  However, if you are going to take a traditional construction modality like timber framing and apply it to current living environmental standards, you must consider the best method for facilitating the two systems.  The "wall truss system" did that extremely well.

I can't tell you how often I meet fine folk like you that either "wish they had," or are trying to find a way to "push back," on the P.E. they hired to approve their project.  I have said this before and I will say it again now, when they (P.E.) are good the are an asset to a project, the rest are nothing but "pain's in my back-side," and trying to get them to understand something, even if they are standing on it or looking at it, they won't except it.  I wish you could have pushed back too, because your common since would most likely have been better than what was done.  I have seen, (and used,) "horizontal nailer" methods.  If I don't use a "wall truss system." or traditional infill method, that is the one to use.  you can run some mechanicals in the system with less drilling, insulating is just changed a little, and the outside still will get the same breathing wall I always insist on.  Is it as nice as the "wall truss system," no not IMO, but it is doable.

As for your observation about material use, well that is another matter.  Yes, there can be no argument that you are using more material than you would in conventional "stick framing," (not supper insulated "stick framing" though).  However, the quality of the structure, with the thicker walls, depth of window seats, facilitated space for extra storage, and the ease of running and modifying mechanicals, all out way the little extra material.  Also remember, you can make these yourself out of lumber you mill or buy locally in many cases, (all in my case), so the construction sight is more self contained in material use/acquisition.

Regards,

Jay

Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: ReidH on December 10, 2012, 11:29:06 PM
Great post on wall truss systems.

I think it would be helpful to have a listing of generic wall and roof sytems that people have had success with.   There seems to be a number of questions around what wall system or insulation system to use.   
 
Pesonally, I would like any wall/insulation system to add to the strength of the structure.  I figure that if you are going to spend the time and money to build a wall system, it might as well help hold the house up which may also make your PEng. easier to deal with.  Durability and life safety should also be taken into consideration when choosing or designing a wall system for a dwelling. 

For my own personal consumption, I have used 4x5 oak studding on the exterior perimeter walls of the timber frame.  These are cut and assembled as part of the timber frame structure following traditional methods more or less and are structural load bearing members.  Interior infill is limited to wallboard inserted into grooves in the studding with room for electrical wiring behind the wallboard in the 2 1/2 inch space remaining.  The exterior surface of the  studded timber frame is well suited for the attachment of 2x10 horizontal sheathing, adding more structure.  2x10 being used as they are generally the cheapest per bdft locally, easy to stack on edge while installing the sheathing and very strong.  Everything exterior of the sheathing can now follow standard "PERSIST" or "REMOTE" air barrier and insulation methods which even your local building inspector might recognize.  Mine did.

Pros - can be installed by one person if necessary; good air barrier; same methods used for roof and walls; uses lots of structural members.

Cons - somewhat costly and time consuming; timber studded interior wall surfaces are not to everyones taste; uses lots of wood.

This is a method I will use again.

Reid
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 11, 2012, 12:31:19 AM
Hi Reid,

Thanks for the feedback and sharing.  If you have pictures or drawing that would also be great to share.  I have a pretty good idea from you description, but a few things are "fuzzy."  (probably becasue I'm tired.)  Thanks again for sharing, your system sound like it works well for you. Most systems like you describe that are done by the builder themselves as part of the "whole house system," always have more pros than cons.

Regards,

Jay
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: frwinks on December 11, 2012, 11:17:59 AM
Reid and I used the same system although I modified mine slightly from the true Persist.
 (http://www.forestryforum.com/gallery/albums/userpics/18964/wall_%28Custom%29.jpg)
 (http://www.forestryforum.com/gallery/albums/userpics/18964/2283/roofconstruction-1.jpg)
 (http://www.forestryforum.com/gallery/albums/userpics/18964/Picture_706_%28Custom%29.jpg)

How are things going Reid, I haven't rolled through Bolton lately, hope you're making good progress?
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 11, 2012, 11:44:40 AM
Thanks so much frwinks,

Take your system make the 2"x4" a rough milled actual 2"x5" then "blow it up" to any width you have with a "span." and you have a "wall truss."  Some would say better, I say an "upgraded model," not better.  Your system and the one I use are closer than the "horizontal run 2x4" method, but that has merit as well.

Thanks again for the graphics,

Jay
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Builder-Bob on December 11, 2012, 01:07:18 PM
This thread has been interesting to read.  Has certainly given me some construction ideas to consider.  Thanks for sharing.

Bob
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: ReidH on December 11, 2012, 09:31:57 PM
Jay,   
The wall system I use is has a few detail differences from Raffs with respect to sheathing and air/vapour barrier and of course the use timber studs versus 2x stock. 
A few pics before the insulation was installed...

 

 (http://www.forestryforum.com/gallery/albums/userpics/23058/797Xharding.jpg)
Second floor before sheathing.
 

 (http://www.forestryforum.com/gallery/albums/userpics/23058/IMG00214-20111102-1658.jpg)
2x10 sheathing on front wall, 1x8 rough sawn on end and rear walls.
 

 (http://www.forestryforum.com/gallery/albums/userpics/23058/IMG00228-20120401-1647.jpg)
Air/vapour barrier.

4 inches of insulation was then fastened with vertical strapping screwed through to the oak studs.  A good impact driver is required to drive the screws into the oak studs. Sorry, I couldn't find a good picture of the foam installation.

Reid
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 11, 2012, 09:40:03 PM
Hi ReidH,

What a beautiful job!  The system you used is very similar to one that Jack Sobon has suggested for years.  Many of the barn to home conversion that a company I consult to does it that way. One of the short comings of "wall truss systems," can be the initial cost of labor and materials.  It really is that much more and you save on mechanical instillation and any future changes, however when you are on a very tight budget and time to finish the project is critical, often your method becomes the one of choice.

Regards,

jay
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: ReidH on December 11, 2012, 10:39:10 PM
Hi Jay, It may be a time saving method when someone else is installing it...  I can make it take a long time to install.   Raff's method realizes good material and labour savings over what I did.

Hi Raff, the house is coming along nicely.  The air barrier and insulation are working wonderfully.  There is no heating system in the addition yet and it is only about a degree cooler than the heated part of the house with only a normal sized door opening between them on the first and second floor.

Reid
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 12, 2012, 12:27:59 AM
Hi Reid,

I have met so many great folks, you referenced Raff, have I forgotten someone?  What was his method?

Thanks,

Jay
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: frwinks on December 12, 2012, 10:49:44 AM
glad to hear things are well Reid, we're still going steady on ours 8)

Jay, I'm Raff  ;D and as you can see in my pics up top, I used the first 2" layer of foilfaced polyiso as my sheathing, air and vapour barrier.  This involved a lot of time spent on the details, countless tubes of black goo, spray foam, peel and stick membrane, Venture tape...etc  You have to be really committed to get the first layer right but you save a good chunk of materials.  I then added a 3.5" layer of foilfaced polyiso, taped, sealed and flashed for a goodNtight install.  Followed by a rainscreen and wood siding.  The sound transmission through all that foam was very high, so I gave in and threw Roxul R14 in the 2x4 cavities. Now nobody can hear my wife screaming to finish the house  smiley_argue01  and the walls are pushing high R40's.
For the roof I used the standard Persist/Remote approach, but used RS 1x material for sheathing (it's also our finished ceiling).
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 12, 2012, 01:33:16 PM
Now I've got it, thanks Raff.  So, for publications purposes and clarification of language, I'm calling all of these system "Curtain Walls," the other would be "Infill Walls."

So within "curtain walls," we have:

Stress Skin Systems.

Stick Frame or 2x Frame Systems, (which one should I use to identify it?)

Wall Truss Systems.

Any other types that you guys think could stand alone or do the all fit into these three?  Once I have consensus, I want to list what types are in all three.  Thanks for the help.

Regards,

Jay

P.S.  Raff, I love the arguing emotion cons that was great! :D
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: PaAnkerbalken on December 12, 2012, 08:31:38 PM
Hi Jay,

 I would like to ask you about an infill type.  I have seen an old cabin/summer house here that is timber framed and infilled with cordwood.  I have read about it but seems a little scary.Seems like you might be constantly after it.  I would like to use that on my cabin i'm building but for the future house, im skepitical that it would be a good idea.  Have you ever used it? Anybody else use it? Any pros or cons? I'll soon be to the point where i have to make a decision and wife likes the looks of the cordwood. ::) Thanks Jason
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 13, 2012, 12:48:38 AM
Hi Jason,

"Cord wood," construction, sometime called "cobbling," has been around for hundreds of years, perhaps over a thousand.  Since the advent of the saw. Rob Roy has done a great deal in promoting it, however he certainly has strayed from the original methodologies.  I would, and have, used it as an infill method, but often it is in a much thicker frame style than you will see published in books or on the web.  It can be drafty if not done well and I would conservatively say that 9 or of 10 people how have done it love it, but say they would never do it again.  I think part of the reason that is true, is like so many other traditional methods, those that try to "re- purpose" a building method, go too far in "reinventing the wheel,"  often forgetting critical methods and materials, which must work in concert with each other.

Regards,

jay

Here are some links to "Kullu," style from the Himalayas of which most of the time they use stone, sometime "wood cobbling." Here also is "Kubbhus" style of Sweden.  From these you can do further searches, let me know if you have more questions.  These different styles of "cobbling" or "nogging" is found frome Eastern Europe to the far East, as well as Canada.

Links to off site pictures are not allowed.


http://www.thehimalayanvillage.in/index.html

http://www.cybis.se/forfun/kubbhus/indexe.htm
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jim_Rogers on December 13, 2012, 09:23:13 AM
A friend of mine visited a cord wood infill house one day.

He sent me some pictures of this unique home.

Here is the outside:

(http://www.forestryforum.com/gallery/albums/userpics/10095/POMPANUCK_004.jpg)

Here are the rafters:

(http://www.forestryforum.com/gallery/albums/userpics/10095/POMPANUCK_015.jpg)

and again:

(http://www.forestryforum.com/gallery/albums/userpics/10095/POMPANUCK_017.jpg)

And if you noticed, some of the cord wood infill, isn't all cord wood.

See here:

(http://www.forestryforum.com/gallery/albums/userpics/10095/POMPANUCK_024.jpg)

Those are different colored wine bottles.

And here is their roof:

(http://www.forestryforum.com/gallery/albums/userpics/10095/POMPANUCK_032.jpg)

I believe it was a "living roof" and of course it was winter time.

Here is their shed:

 (http://www.forestryforum.com/gallery/albums/userpics/10095/POMPANUCK_041.jpg)

So it can be done and with a little thought, it can be interesting as well.

Jim Rogers
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: PaAnkerbalken on December 14, 2012, 10:57:44 PM
Jim or Jay,
I've also seen here on some old tf houses that are abandoned, that some of the board siding has come off to reveal that it was infilled with brick. They didnt use cement for morter they used what looks like orange clay. ???  Is this method any better than cordwood? More stable?  It sure looks neat, seeing the beams and the brick flush to the outside.  How would you run your plumbing and electrical with those type of enclosures?  Jason
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 15, 2012, 12:22:22 AM
Hi Jason,

Well I will work backwards on your question.  As for the mechanicals that you normally run in a wall, with any of the infill types, you really can't, not effectively anyway.  Should you need to change, update or modify something you did embedded in the wall, well that involves a lot of ripping and tearing.  Most of the time you either have to run mechanicals in the ceiling, floor or over the surface of the wall.  I have seen the use of "thickened" baseboards to hide such things and that is probably the best of the lot, for a method.

Your second observation is most accurate, I commend you.  It speaks to what I was saying about folks, "reinventing the wheel."  Since just before WWII concrete started becoming the "miracle" material for just about everything from building skyscrapers, to re-chinking a log cabins and filling voids in hollow trees.  The skyscraper and a few other modern application, if done with the correct mix and application, it has turned out, are the only places you should ever "stick," or use concrete.  Proper lime based mortars are far superior to any of the Portland based ones, matching the brick in flexibility and expandability, as well as, taking and releasing water in concert with each other.  In many cases clay mortar would be better than cement, should you choose to use this system.

I'm with you in liking the look of "cobbling," and there is one way to get the best of both worlds.  Use the cord word only part of the way up the wall on the ground floor of a structure.  Like a wainscot up to chair back height or so.  You can even use a thickened ledger cap to hid your mechanicals if need be.

Regards,

Jay

 
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Satamax on December 17, 2012, 06:19:29 AM
Jim or Jay,
I've also seen here on some old tf houses that are abandoned, that some of the board siding has come off to reveal that it was infilled with brick. They didnt use cement for morter they used what looks like orange clay. ???  Is this method any better than cordwood? More stable?  It sure looks neat, seeing the beams and the brick flush to the outside.  How would you run your plumbing and electrical with those type of enclosures?  Jason
Jason, what you talk about sounds like "colombage"

Links to off site pictures are not allowed
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: jueston on December 17, 2012, 09:11:36 AM
that link took me to this picture, and i thought i would include, no matter what infill style you go with, towers are always in style.

Links to off site pictures are not allowed.
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 17, 2012, 12:04:06 PM
Hello All,

Good Day Satamax,

I do not want to assume you are a native French speaker just by the region you hail from, I do not have command over the language.  I have been doing extensive research in multiply languages for about a decade and a half, (thank's to technology and dogged patients.) So perhaps what I am about to write is incorrect.

"Colombage," in French only means timber, or in this context, "timbering," and does not speak to the wattle (clayonnage) that goes between the timbers or the mud cob (en torchis) that covers it.  I did a quick search and the best passage I could find and translate is as follows:

Original French:
"Construction d'une maison en torchis et colombage sur la base d'un ancien pressoir à pommes. Le torchis a été posé sur une structure liteaux (clayonnage) cloué a l'arrière des colombes, permettant ainsi d'éviter les ponts thermiques. Le torchis redevient un matériau de construction dans l'ère du temps, il s'adapte parfaitement a la construction bois en lui permettant de respirer."

Translation to English:
Construction of a house made ​​of mud and timber on the basis of an old apple press. The mud was placed on a structure battens (wattle) is nailed back of columns, thus avoiding thermal bridges. The mud becomes a building material in the era of time (to mean in the past-history,) it adapts perfectly to the construction wood allowing it to breathe.

Hi Jason,

Your observations have led us to some more good information.  If you learn to do searches in other languages you can discover all kinds of things about traditional timber framing and building methods.  The more I read the more I have learned that just plan old "clay mud cobbing, daub or cob," is probably still one of the best building materials you could use for infilling between timbers or logs.  If done correctly it can be very serviceable and secure.  It has been pointed out that "concrete" or "portland mortars" stick better, and this may be true, but concrete also is excellent at decomposing wood by it's hydrophilic (water-loving) nature. Concrete does not allow wood to dry out completely thus being a major contributor to "dry rot" wherever it is in direct contact with wood.

Regards,

jay
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: PaAnkerbalken on December 17, 2012, 08:51:21 PM
Thanks Jay and Satamax,

I'm guessing you should use a rot resistant wood then in your frame if you were to use that kind of infill? My posts(8x8) are white ash. Sills are(8x8) EWP.  Would the sills and posts rot out if i were to fill in with stone, brick or cordwood? I noted that you said daubing or clay is more breathable, so maybe they won't rot? I would probably try the clay we have here for the "mortar" between the cordwood.  I'm leaning toward the cordwood simply because of the weight, availability and time factors but wouldn't be apposed to starting out with stone or brick (like wainscot) and then switching to cordwood the rest of the way.  Is something like that doable? Sounds like a crazy amount of work but unique! :o   Jason
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 17, 2012, 09:07:58 PM
It is very doable, be creative, and yes it is a lot of work!  I would always use clay or a lime mortar and at this stage in the game seldom do I consider portland (cement,) for anything short of form work of some type, but only after a traditional method has been thoroughly considered do I even consider it then. 

If you have a good source of clay, wood chip and/or straw, and a way to mix it, (if it is just you and maybe a few others you are going to need a power mixer or a lot of muscle and time,) you will be on your way to something grand.  Good luck and keep us updated with your progress and thoughts.

Regards,

jay
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Piston on December 18, 2012, 09:15:47 PM
This is a really informative thread.  I read about the larsen truss system in one of Benson's books.  In fact, I think those pics that Jim posted earlier are the identical pictures from that book.  It sounded pretty interesting and seemed like a good system. 

I have always thought that if I ever got off my butt and built something like a shed or cabin, then I would use the horizontal nailer system if I was trying to do it economically, but the Larsen truss system also looks interesting.  Thanks for bringing it up, there's some really good info in this thread for alternatives. 
Title: Re: Wall Truss Systems For Enclosing Timber Frames
Post by: Jay C. White Cloud on December 18, 2012, 10:11:54 PM
Hi Piston,

If you set up a jig and have a table saw, and chain mortiser, you can make them really quick.  To of the young men I taught built 250 mm wide trusses for a 12 m x 12 m house in 1.5 days or 24 man hours.  Attaching them to the frame was strait forward and only took another 16 man hours.  They had 50 mm x 125 mm stock delivered, then ripped each one down to 50 mm x 50 mm and 50 mm x 75 mm, then when they feed the two pieces through the jig, a single plunge of the chain mortiser cut a mortise 20 mm x 50 mm in both pieces with one pass.  The spans are cut on the table saw. The spans are set to 500 mm on center within each truss, and the trusses themselves are placed 600 mm apart on the frame, (truss centers can range from 480 mm to 600 mm seldom outside that range when applied to a timber frame.)

Regards,

Jay