[Strawbale] Strawbale position
Andrew at StrawBale...
Tue Oct 12 21:08:20 CEST 2010
Lots to comment on here and I decided to take my comments back to my
http://www.strawbale.com/top-10-no-bales-on-edge) rather than continue with
long back and forth posts both here and there. I hope you will take a moment
to read my response to Derek's email. Clearly we disagree, which is fine. I
hope you will consider both points of view before you make any decisions on
your own projects.
On Tue, Oct 12, 2010 at 11:25 AM, Derek Roff <derek at unm...> wrote:
> I agree with Andrew that the research on R-Value of flat vs. on-edge is
> not totally rigorous, yet tends to indicate similar total R-value for a
> bale in either position (meaning higher R-value per inch/mm for bales
> on edge). I have doubts about the general applicability of the
> research, because the straw orientation in the bales that I have worked
> with is not terribly consistent. As Andrew mentions, it depends in
> part on the baler.
> If your climate isn't totally extreme, minor R-value differences
> between bales don't matter. If your climate is extreme, consider using
> jumbo bales. Usually, it makes sense to put your energy into good
> design, good detailing, and good roof insulation. Whether flat or
> on-edge, strawbale walls give enough insulation, that other aspects of
> the building have much more impact on energy conservation than the
> minor differences in the different well-built strawbale walls might.
> On the other hand, I disagree with Andrew on the validity of stacking
> bales on edge. I like it. I note that many of the top builders, such
> as Bill and Athena Steen, use or prefer on-edge stacking. Both methods
> work fine, in my opinion. Each has different advantages and
> challenges. Here's my take on Andrew's 10 Reasons to Never Stack Your
> Bales on Edge. I will list Andrew's reason text in full, and then my
> 1. Strings on the exposed face mean no notching around posts and thus
> a thermal break at each post.
> I agree that the strings are exposed, which makes notching difficult.
> I'm not a fan of notching, with bales flat or on edge, although it
> makes sense in some designs. It is disingenuous to say that no
> notching causes "a thermal break at each post". It would be foolish to
> design a thermal bridge (not "break") into your wall at every post
> ("thermal break" usually indicates something that stops heat flow; a
> "thermal bridge" allows it). Common methods for avoiding a thermal
> bridge include putting the posts fully inside the building envelope,
> fully outside, or insulating behind the posts with straw flakes or
> other insulation material. Or building Nebraska-style loadbearing
> designs. Each option has pluses and minuses.
> 2. Bales are not sturdy. If you throw a bale off the stack it will land
> on the flat 99 out of 100 times, not on edge.
> All testing shows that bales are plenty sturdy in either orientation.
> Jeff Rupert's University of Colorado testing shows that bales on edge
> were substantially stronger than bales laid flat, in handling extreme
> loads (p.79, Design of Straw Bale Buildings: The State of the Art,
> Bruce King, et al, 2006). However, the differences are not relevant to
> building, because bales are strong enough in either orientation, wall
> loading in a house is much lower than in the tests, and the primary
> loads on a wall will be carried by the plaster skins, in any case. Or
> by the posts, if the building isn't loadbearing. I don't know if
> Andrew has actually maintained careful records of the side his bales
> fall on when he throws them off the stack, but this has nothing to do
> with sturdiness of bales in a building. It strikes me as odd that this
> would be used as proof or explanation. Perhaps it's humor.
> 3. Any framing in the wall eliminates the running bond system, thus
> weakening the walls.
> Maybe I am missing something, but as I read it, this assertion is
> completely false. Running bond stacking is used in all the on-edge
> buildings that I have worked on, and most that I have seen in books and
> magazines. There are a few exceptions, of course, as there are for
> flat-laid. Re-tying bales to custom lengths is needed to deal with
> door and window framing, whether bales are laid flat or on edge. If
> this is about notching, then it is a repeat of item 1. I've helped
> with a dozen buildings with bales on edge, and they all had running
> bonds and framing.
> 4. No weedwacking is possible to smooth the walls.
> I'd go 50-50 on this one. Stacking on edge means walls are smoother to
> start with, and less weedwacking is needed. Removing the stray
> irregularities seems easier to me, when the bales are on edge. On the
> other hand, if you want to do major re-sculpting of a wall with a
> weedwacker, stack your bales flat.
> 5. Running electrical is difficult because you have to cut chainsaw
> grooves around strings.
> Depends. Almost all the electrical runs in a wall are horizontal, and
> the easiest option is to put the wiring between the bale courses. In
> any case, horizontal runs at any height won't cross the strings. Some
> codes/jurisdictions have special rules, such as putting wiring in
> conduit. Vertical runs to switches and lights are likely to be near
> doors, and on interior, non-strawbale walls. The strings have the
> potential to be in the way in a few places, but the number is likely to
> be small. Or larger, if the wiring design is done with no thought to
> the bales.
> 6. Corners are unsupported because you can’t notch the bales around the
> posts, therefore there is no overlap.
> This seems like a repeat of number 1, with focus on the corners. It's
> just as misleading. Every on-edge building that I have worked on, seen
> pictures of, or heard about, where bales meet at a corner, has
> overlapped the corners in the same running bond as flat-laid bales.
> Are these corners really "unsupported"? All the historical Nebraska
> buildings were loadbearing, with no posts at all, in corners or
> elsewhere. Many modern buildings are also loadbearing. So the corners
> can have plenty of support, with no posts at all. But supporting posts
> can also be placed at or near the corners when you stack on edge. See
> item 1 for a couple of the options. I've found that notching bales at
> the corner, where bales are coming from different directions on each
> successive course, is even less fun than notching in the middle of a
> bale. Worth doing, if that is your design, but other options exist.
> 7. Niche construction means cutting the strings and weakening the wall.
> It almost certainly means cutting the strings, but it is doubtful that
> this weakens the wall. As mentioned above, the primary loads in a wall
> are taken by the plaster skins, or by the posts, and even unplastered
> bales create walls that are vastly stronger than they need to be to
> take building loads, according to testing. Windows and doors weaken
> the wall vastly more than niches, but we've figured out how to deal
> with that. Use similar strategies, if you are making a giant niche.
> By the way, some very well respected builders, such as Tom Rijven and
> David Lanfear, cut all the strings on every bale, in order to improve
> the strength and efficiency of their walls. Chris Magwood and others
> have experimented with stacking a continuous wall, and then cutting out
> window openings with a chainsaw. They cut a lot of strings, and their
> walls seem fine.
> 8. The shape of the bales requires more stuffing when on edge.
> Maybe, but I doubt it. The ends of the bales interface in the same way
> with either orientation, so the amount of stuffing between a pair of
> bale ends is the same. The depth of the wall is less with on edge
> stacking, and a wall needs fewer courses of bales for a given height.
> So I think on edge is ahead. If you pre-compress your wall, which I
> favor in every case, then on-edge bales conform to each other more,
> between the courses, than flat-laid bales, again leading to less
> stuffing. But both methods still require a lot of stuffing, for my
> 9. The exposed surface of the bale has less “tooth” for plaster than
> when the bales are stacked on the flat.
> I agree. The difference is noticeable, but not overwhelming.
> 10. Wall settling may be more as the strength of the straw bale is not
> from side to side but from top to bottom.
> The best laboratory testing, which I quoted under item 2 above, is that
> strawbales are stronger on edge. Many people wonder about that test,
> but it is clear that walls are strong enough in either orientation, and
> again, the primary loads are carried by the plaster skins or the posts.
> The best historical testing is the 100+ year old Nebraska buildings.
> They are built with bales on edge, at least in the ones I know of that
> have been verified. In many of these buildings, you can tell bale
> orientation from the photos taken during construction, and from truth
> windows. They are loadbearing, and the windows and doors are intact,
> so there hasn't been much settling.
> So my scoring is a bit different than Andrew's. I agree with one of
> his points, and there are a few where I am in partial agreement. He is
> welcome to his opinions and preferences, but I'm bothered by the
> inaccurate reporting and illogical arguments in some of his points. My
> belief is that you can build great buildings either way, and that there
> are pluses and minuses for any and every building choice.
> I will add a few words on one question that didn't enter into Andrew's
> list. If you want to shape the bales or the wall in certain ways,
> there may be an advantage to one method or the other. For circular
> buildings of small to modest radius, it's easier to form (distort) each
> bale into part of the needed arc, if they are on edge. But you have to
> sew the inside strings back to the bale, to follow the reshaped bale.
> It's not difficult, but it takes extra time. Putting an arc in a
> flat-laid bale is harder (especially 3-string rice bales), but the
> strings are more cooperative, except in the smallest buildings. For
> large, round buildings, the bales don't need to be distorted.
> Around windows, it's easier to carve a small bullnose curve on a
> flat-laid bale. For a bigger (more normal-sized) curve, one of the
> strings of flat-laid bales gets in the way of carving your curve. Of
> course, there are ways to deal with that, such as running an extra
> string or two, to pull the main string off its course at the end of the
> When carving a large arc on the end of a flat-laid bale, the straws
> tend to stick out in all directions like Pappy's beard in the Popeye
> cartoons, which makes plastering a beautiful curve a little more
> difficult. It's still quite doable. Re-tying an on-edge bale to
> approximate the bullnose curve shape that you want is possible with
> many bales, although again harder with rice. It means re-tying every
> bale around the window or door, but at least half of those have to be
> re-tied in most designs, flat or edge stacked. Some people would
> rather build the curve with lath, and stuff it with straw. I'm not a
> fan of that.
> The more low-relief sculpting that you plan, the more advantageous it
> is to lay your bales flat.
> I hope this helps,
> --On Tuesday, October 12, 2010 7:16 AM -0700 Andrew Morrison
> <Andrew at StrawBale...> wrote:
> > Hello Jure. There are some studies out there about the insulation
> > value of straw bales stacked horizontally (on the flat) and
> > vertically (on edge); however, I do not think that any of them are
> > terribly accurate. In each, there are details that are subjective. I
> > do believe that they all conclude that the straw orientation does
> > indeed affect the insulation value of the bales, thus making bales
> > stacked on edge higher R-value per inch than bales stacked
> > horizontally. This effectively gives you the same R-value for the
> > bales stacked either way, simply allowing you to use less space in
> > your home for the actual wall thickness. That said, many new baling
> > machines are orienting the straw differently, or not at all (chopped
> > straw from combines for example is so small that the straw
> > orientation is every which way).
> > Even though the R-value is higher per inch in a bale stacked on edge,
> > I don't believe it is worth the effort of stacking walls this way.
> > There are so many disadvantages to stacking bales on edge and I
> > strongly recommend you don't bother with the idea. I have written a
> > "top ten" list of reasons not to build with bales on edge on my
> > website, www.StrawBale.com. You can view that article here
> > (http://www.strawbale.com/top-10-no-bales-on-edge) for more details
> > as to why to avoid stacking on edge.
> > Best of luck and I hope your project runs smoothly from design to
> > completion.
> > Andrew
> > On Tue, Oct 12, 2010 at 3:57 AM, Sport Hotel, Jure Pozar
> > <jure.pozar at gmail...> wrote:
> > Dear all,
> > I am in the phase of designing our straw bale house and I have heard
> > that if you lay the straw bale horizontaly it has the same isolation
> > conductivity as if laid vertical. Lets presume the bales? dimension
> > is 45 x 35 x 100 cm which would mean that laid horizontaly the
> > strawbale wall would be 45 cm and verticaly would be 35 cm (the
> > isolation at this second option is supposed to be better due to
> > straws which are in vertical position). Does anybody know of tests
> > performed and published of this particulat subject. If this is true
> > you need much less strawbales to built your house. I am of course
> > talking about post & beam method. Probably this would present a
> > problem at loadbearing method. Does anybody know of any difficulties
> > when building post & beam and bales put vertical?
> > I would appreciate any answer
> > Regards,
> > Jure PoÏar
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