[Strawbale] Strawbale position

[Derek Roff]

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 
response.

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 
tastes.

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 
bale.

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,

Derelict


--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