SB: Re: Vault in the desert -- was pinning

[Mikal Jakubal <mjakubal@asis.com>]

Hi Kirk,

 <snip>
>The alternative, placing a roof structure on top of the
>vault, poses its own set of problems requiring solutions.  How does one
>attach the roof structure in a secure way so that high winds don't send
>pieces flying over the hill?

Putting a separate roof on a vaulted bale building is not really that
difficult, and in fact has some great advantages. The obvious one is that
you can sleep lots better on rainy nights because you don't have to worry
about whether or not you missed any cracks on your quarterly surface check
of every inch of the entire structure!

More to the design point, large shed roofs (like I have on the south side
of mine) give you lots more space (closed in or not) and keep roof run-off
well away from the foundation. Most vault designs will have buttresses. By
roofing over these spaces, they become much more useable as living space.
Don't neglect the buttresses as design elements! They have so much more
than mere structural potential. One of the "bays" between the (four)
buttresses on the north side of my place has its own shed roof and
functions as the entry way. The two other bays are a storage area, and a
pantry off the cooking/eating area. Both of these last two spaces also have
rooms above them, covered with their own little vaulted roofs (glu-lam
stick framed). 

The interior floor area of my place is 640 square feet (16' x 40'), but
with all the buttress spaces, alcoves, covered porches, arcade and so on,
the total comes up to @2,300 square feet of both conditioned and
unconditioned space. The point is, you can start with a relatively small
vault (cheaper and easier to build than a big clunker like mine!) as the
primary living space and then add enough space around it for whatever else
you need. Way cheaper and easier to add lightweight attachments than have
to make the main structure big enough to accommodate everything. 

As to attachment, that's easy. The roof frame is bolted through the bales
with either 1/2" or 3/8" all-thread and secured on the inside of the bale
surface with 8"x8" mesh "washers". The best material for washers is
heavy-gauge gravel screen. I get it free or nominal charge at the local
scrap yard, who gets it from the local gravel plant. They scrap it when it
gets too many holes in it. I like the 1"x1" hole size. It can be cut down
with a torch, an angle grinder or a skill saw with a metal cutting blade.
Pound the bolt through the bales, slip the mesh piece over the end, add a
big flat washer or a piece of 1/4" or similar bar stock with a hole drilled
through it, put on a nut and tighten it down. Bombproof and easy. Pound the
bolts with a thick wooden block so you don't trash the threads, and have a
thread-cutting die handy for when you do. 

A way to save money on the all-thread is to find scrap rod stock, cut it to
length and thread the ends yourself. The local machine shop let me use the
thread-cutter machine there for a nominal fee. Doing it by hand with a die
is too much work! This is also good advice for anyone who is still using
all-thread to hold the roof-bearing-assembly to the foundation. Thread the
ends of scrap rod and attach short all-threads with coupling nuts.  

Even if you don't want to do anything complex or fancy, metal roofing or
any kind of shingles will bend to the curve of the vault easily.

If you haven't seen it, here's some photos from last year. There should be
new ones soon.

http://www.strawbalecentral.com/jakubal/vault6.html

http://www.strawbalecentral.com/jakubal/vault1.html


Mikal 
--the Barbarian who carefully catches and relocates scorpions and black
widow spiders away from his house, and who lives happily with bazillions of
wasps except when he clumsily hits their nests with the brush cutter and
gets what he deserves.

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