Re: [papercreters] Re: Reciprocal roof

Greetings,

We are at the point of ordering our wood. Unlike most people, we are
going to have to buy our poles, no woods on our land. Balancing the
diameter of the poles between strength and ability to lift them into
place is an interesting challenge. We are looking for strength tables
for yellow pine logs, machine barked and kiln dried.

We are in the process of building a 1/24 scale model of our building.
It is teaching us a lot. And yes, I did realize that I am building a
lever. My original design had two henge, one inside the other. Then I
realized I would rob my roof of strength if I put the outside one in, as
it would no longer balance the center of the roof.

The building will be 16 sided, thus 16 main poles for the roof. The
diameter is 40', with a 5' over hang. So we will be using 30' poles.
My original estimate was for class 2, that is 8" to 10" at the top, but
I do believe they are too big to work with, so we are going to go down
to 6" to 8" tops. The henge and uprights are built from heavier posts,
being a size up, as in 10" to 12" diameter at the top. Fortunately, I
do have a front end loader that will help us get them into position.

We are adding a porch on part of the building, for 3 sections, so I will
have 4 posts at 40' to deal with. We are also looking at doing 16
secondary rafters, that come off the mains and go to the halfway point
between the mains, on the henge.

The roof will be covered with 1"x then tar paper that will get painted.
The painted tar paper should last long enough for us to get the
papercrete, a mixture of paper and Portland only as 50/50 by weight, 1'
thick, up there. It will be made into blocks, down on the ground and
mortared into place. Then covered with petrified hessian.

A central cupola will be installed over the opening in the roof to act
as a heat chimney, a very valuable addition to a home in Texas.

Our maximum wind load is a category 2 hurricane, no snow load.

Does this sound reasonable?

Bright Blessings,
Garth & Kim Travis
www.TheRoseColoredForest.com
Bedias, Texas

On 12/2/2012 1:31 AM, JayH wrote:
> WARNING! NERD ALERT POST FOLLOWS!
>
> I have not done the math to verify the accuracy of the following
> spreadsheet, so I make no guarantees to its accuracy. That said, at
> first (very rough) glance it appears to put out results that seem
> reasonable.
>
> http://www.abrazohouse.org/wp-content/uploads/2008/11/reciprocal-roof.xls
>
> Hope that helps at least get you started in the right direction.
>
> What that spreadsheet won't do is give you diameters of your poles.
>
> Calculating the diameter of your poles would involve reciprocal roof
> load calculations involving weight of every single other material
> included in completing the roof, timber strength calculations based upon
> which species of wood you would be using, grade of wood, span distances,
> roof pitch, wind and other live loads, and some other factors that are
> unknown at this time.
>
> Having said all that, most reciprocal roofs get built in areas that do
> not have building codes, and are engineered by people that look at a log
> laying on the ground, maybe heft it to feel how heavy it is and make an
> extremely subjective ... "this ought to be big enough" judgement for
> themselves and just go with it.
>
> Personally, I think doing load calculations makes sense, but then I
> kinda enjoy doing math, physics, statics, and geometry. The nerd factor
> in your genetic makeup probably varies from mine. (Probably makes you a
> lot more entertaining at parties too. My ability to do second class
> lever calculations far exceeds my 2nd class dancing ability.)
>
> Warning #2: Anyone that got my lame joke and knew that reciprocal roof
> poles are simply a bunch of 2nd class levers leaning on each other is at
> extreme risk of being a 2nd class dancer. Probably should see your
> doctor and get yourself tested for nerdfluenza.
>
> --- In papercreters@yahoogroups.com
> <mailto:papercreters%40yahoogroups.com>, Garth & Kim Travis <gartht@...>
> wrote:
> >
> > Greetings,
> >
> > I would love to hear from anyone that is interested in reciprocal roofs.
> > I have read all the information I can find, which is not much. I am
> > finding myself very challenged when trying to figure out what size poles
> > I need for my place. The poles need to be ordered fairly soon, as they
> > will take three weeks to get. They are cutting, debarking and kiln
> > drying the poles just for me.
> > --
> > Bright Blessings,
> > Garth & Kim Travis
> > www.TheRoseColoredForest.com
> > Bedias, Texas
> >
>
>
>
> No virus found in this message.
> Checked by AVG - www.avg.com <http://www.avg.com>
> Version: 2013.0.2793 / Virus Database: 2634/5930 - Release Date: 12/01/12
>


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