Re: SB: Small, cheap, easy, and temporary

[Speireag Alden <Joshua.M.Alden.91@alum.dartmouth.org>]

Sgrìobh luc:

>My thoughts are a square, approximately 15x15 structure with as 
>simple a foundation as possible (just packed earth with some sort of 
>covering?), unfinished (i.e. no stucco, adobe, etc.) load-bearing 
>walls (pinned with rebar?), and a simple, inexpensive roof.  We 
>would integrate several salvaged single-pane windows and one door 
>into the walls, probably using lintels above each, and have a 
>lean-to type roof, possibly of tin (or of sheets of translucent 
>plastic?).  I would intend it to be designed to last a couple of 
>years or longer.
>
>I'd really appreciate suggestions, ideas, or the wisdom of 
>experience to inform this project.  What kinds of foundations might 
>we consider?  Would packed earth work?

     For a strictly temporary structure which isn't intended to be air 
tight, you can build it right on the ground.  Make sure that the 
slope immediately around it is away from it, at least slightly, so 
that water doesn't collect in the building area.

>   Does it seem plausible to build load-bearing walls?

     Certainly.

>   What sort of roof plate or other roof structure should we 
>consider?  How should that be attached to the foundation?  What 
>kinds of roofing materials should we consider?

     Probably one of the easiest from conventional materials is 
plywood or OSB decking, with roofing paper on top of that and then 
shingles nailed down.  However, you're going to have to dispose of 
the shingles at some point in the future.  For a temporary structure 
I would question the wisdom of using something which should last 
twenty years and can't really be re-used easily.  Instead, you might 
try a simple earthen roof, since failure of the roof would not be 
catastrophe.  The simplest earthen roof is decking over rafters, a 
layer of 6-mil poly plastic over the decking, (an optional layer of 
used carpet to protect the plastic,) a layer of carefully sifted dirt 
perhaps an inch thick on top of that, a second layer of 6-mil poly on 
top of that, and then perhaps three inches of dirt on top of that. 
Seed with grass.  Then, when you take the structure apart, all 
materials are re-usable, especially if you use square-drive screws to 
attach the decking to the rafters.

>   Are there other methods than rebar that we should consider for 
>securing the bales to one another?

     Yes.  Internal rebar turns out to be greatly inferior to exterior 
pins.  With exterior pins you put pins in pairs on either side of the 
wall and tie them together tightly through the wall, using baling 
twine or wire.  That puts the stiff part of the wall on the outside, 
where the movement is, instead of on the inside.  It's like using an 
I-beam instead of a piece of sheet metal.  It's not much more 
difficult and will give you an extremely strong structure.  And, it 
can be disassembled.  For the pins you can use bamboo, stripped 
saplings, rebar, or what-have-you.

     In February 1998 I built a load-bearing shed much as you 
describe.  I used it for tool storage and sometimes as a workshop out 
of the rain.  I hadn't intended to still be using it this long, but 
it's holding up fine.  Awhile back I wrote an account of it, with 
lessons learned.  I've reproduced it below.  I hope that this helps.

-Speireag.

---

     I built this thing in February, during a thaw when we could 
shovel down to the ground (through the snow).  I laid the first row 
of bales directly on the ground, but I wrapped plastic around three 
sides:  the underside, the outside and the topside.  I left the 
inside open so that vapor could get out.  The underside was necessary 
to keep ground moisture from going directly up into the bale walls, 
the outside was necessary to keep runoff from running into the bales, 
and the upside was necessary to keep the outside up.  If you follow 
me.

     Exterior dimensions are roughly twelve by twenty-one feet.  A 
single doorway in one of the short ends provides access.  We hung an 
old blanket there for privacy and protection from the wind.

     I laid out the bales and then did a running bond.  At the time I 
had no tools to make half-bales, so I just did the best I could by 
stacking regular bales sideways.  That means that I have a bit of a 
shelf on the inside (good) and on the outside (bad).

     Mistake #1:  No half bales, because we were rushed.  Take the 
time to make half bales and do it right.

     We stacked things up so that the roof would be low but well clear 
of our heads.  If memory serves, it's five bales high on the south 
side and seven bales high on the north side.  The south side had two 
windows one bale wide, for light.  In order to provide the roof with 
something to bear on where the roof crossed the windows on the south 
side, I put down two long but twisty trees, each maybe three inches 
across at the thickest, along the south side, where I left two 
windows.  These trees seemed totally unsuitable at first, but I 
figured that the weight of the roof would pin them in place with no 
additional fastening.  I was right.

     However, the two windows meant that the roof on the south side 
was supported by fewer bales, which meant that fewer bales were 
holding up the same weight, so there was more weight per bale. 
Therefore, the south wall sank further than the north wall when the 
walls compressed.  That was good, because that was the way I wanted 
the slope, but the south wall sank a lot, and I now cannot stand up 
all the way anywhere inside that shed.

     Mistake #2:  Didn't make the walls high enough, because I didn't 
think that they'd compress that far.

     On top of the walls, I laid vigas across the top, from the south 
wall to the north, so that they were parallel with the short walls. 
On top of these, I screwed down OSB (oriented strand board), which 
was cheaper than plywood.  I screwed right through the OSB and into 
the green vigas.  Worked fine, but the screws tended to strip.

     Mistake #3:  Used Phillips-head screws, not square-drive.  In 
every other phase of my house construction I used square-drive 
screws.  I cannot emphasize enough how important this is and how easy 
it makes certain things.  This is one of my cardinal rules now. 
Remember how Build it With Bales has all sorts of recommendations on 
this and that but when they come to a toe-up, they say, "Just do it. 
Trust us."  Well, when it comes to square-drive screws, just do it. 
Trust me.  (And for those of you who say that the bits strip, you're 
buying cheap bits.  I've been ordering from McFeely's Square Drive 
Screws in Virginia, and the bits last for well over a thousand 
screws, and that's with some awkward screwing and some camming out.)

     On the north wall, the long wall without windows, I simply laid 
the vigas on top of the bales.  I didn't put any kind of beam up to 
distribute the weight along that wall.

     Mistake #4:  Didn't put a bearing beam on the north wall.  So the 
bales compressed differentially.  This turned out not to be a big 
deal, but it would be easy to fix and for the next temporary 
structure I'd lay out two more twisty trees, just like on the south 
wall.

     On top of the OSB, I laid down two sheets of 6-mil polyethylene. 
On top of that I put a layer of cardboard to protect the poly, and on 
top of that I put a layer of bales, because I wanted to experiment 
with the bale roof.  This resulted in a very heavy roof, which I knew 
in advance, but I didn't fully appreciate how heavy.  The walls 
compressed more than I thought (see mistake #2), and the walls began 
to buckle.

     Mistake #5:  I didn't brace the walls before loading the roof 
with bales and then getting them sopping wet.  I had to retrofit that 
spring.  I took 2x4's and ran them in parallel, at an angle, on 
either side of the bale wall, so they went from ground to roof 
diagonally.  I drilled each 2x4 three times (the long way; through 
the 3.5-inch dimension), ran all-thread through the walls and the 
2x4's, and screwed those suckers together.  That braced the walls up 
very well, and the whole thing has been stable ever since.

     Except the east wall.  That's the one with the door in it, and 
it's a short wall.  So, there's not enough wall to brace against the 
weight of the roof once the south wall compressed a lot and the north 
wall wanted to head south.  I had a cargo trailer (forty feet long) 
parked behind the shed.  I ran a chain from one of the roof vigas 
where it poked out on the north side and chained off to the frame of 
the trailer.  That stopped the southward movement of roof and walls. 
A few weeks ago I took the chain down; it was slack anyway.  At some 
point in the year after I chained it, the walls decided not to move 
any more.

     Mistake #6:  Not enough wall on the east side to brace the 
corners enough.  Make your walls long enough to brace the other 
walls, and put your doors far enough from the corners so that the 
corners have lateral bracing.

     Even with all the mistakes, it still works great.  I have all 
kinds of tools out there.  The door has no frame and no door; it's 
just a doorway.  The windows let in light.  During construction we 
had the composting toilet out there for everyone to use, vented to 
the outside on the west wall.  The only signs of decay at this point 
are around the edges of the roof where the poly has succumbed to the 
ultraviolet and fallen apart, so the edges of the OSB are soaking up 
some water on the east side.  However, the OSB is still holding the 
roof up fine and I expect it to last for a few more years until I 
build the real shop / shed / carport / wood pile.

     It's very sturdy.  Check the archives for my story about how I 
felled a very large oak tree onto it.
-- 
Speireag Alden, aka Joshua Macdonald Alden

...the last word in ignorance is the man who says of an animal or 
plant: 'What good is it?' --Aldo Leopold, _A Sand County Almanac_ 

-------------------------------------------------------------------------
To unsubscribe from the list, send a message to:
   <strawbale-unsubscribe@crest.org>

or for the digest to:
   <strawbale-digest-unsubscribe@crest.org>

Please send any list administration questions to
strawbale-owner@crest.org