Existing Dome......
Already been done.......in 1980
It is a mess, and I roofed it, giving the owner some ideas concerning the
problems.
It is sheetrocked, and insulated.....
The Dome builders must have built many of these before they started getting
complaints.
I told the owner to call Oregon Domes and relay the problem to them.....
They built it, and are still in business but I am sure with better improved
ways to vent the roof.
All roofs need venting............except for solid insulation installed
tightly.......
jloomis
wrote in message
...
On Wed, 9 Apr 2008 07:46:08 -0400, "Owen Lawrence"
wrote:


"Lee Michaels" wrote in message
m...

"Owen Lawrence" wrote


As for the insulation, how about the sprayed foam insulation? I have no
ideas how it would handle the water/condensation issue. But is a super
good insulator, makes the structure very quiet and can be applied
quickly.

You might look at these two ideas if you want to build a dome.

I like the idea of "quiet", since I want to put a grand piano under this
dome. One goal, however, is that the structure be easy to maintain. My
only experience with sprayed foam insulation is with my new windows. It's
time consuming cutting through that stuff if you must, and it never really
comes off any surface it touches.

Whatever approach I use, I'd like to build a prototype, first a shed, and
maybe a new workshop. First, I'll need land, which isn't getting any
easier
to find now that the baby boomers are all retiring.

- Owen -

Came in 1/2 way thru this thread so have no idea if my observations
have already been suggested/reported. You do need ventilation for
whatever roof structure you propose to use.
What are your plans for finishing the interior of the dome? Drywall,
panelling, T&G wood?- They're all going to be time-consuming
major pain-in-the-ass installations, given the geometry of the
construction; or did you intend to leave the insulation exposed?
If the insulation is to be left exposed you're still going to need a
vapour-barrier to prevent moisture from within the house (cooking,
showers etc.) from entering the insulation and defeating its purpose
unless you plan to use the sprayon the OP was mentioning.




At any rate you need a roof ventilation system- check with your
local government as to what is required by your local building code.
We are in the final stages of completing a new house (acting as our
own general contractor) and what is required by code here- British
Columbia, Canada- is a continuous venting system from soffit to
roof peak. There's a formula regarding number of vents based upon the
square footage of the roof. I realize that with a dome there aren't
going to be any soffits but a continuous path for roof ventilation
can still be easily provided; just install roof vents as low on the
side of the dome as you feel comfortable with, and install more vents
closer to the "peak" of the dome.
That being said, you'll still require channels to conduct the
colder, outside air across the upper surface of the insulation layer
and out thru your upper vents. In our case (conventional woodframe
construction but with vaulted ceiling throughout) we accomplished this
airflow by having the insulators install pieces of small ductwork to
the interior side of the roof decking. I cannot for the life of me
remember what this ductwork is called but it comes in pieces 4' long
and in widths to accomodate the distance between the roof trusses and
provides a tunnel, as it were, between the interior side of the roof
decking and the exterior side of the ceiling insulation. The
fibreglass batt insulation we used (R-28) is a crush-fit to the
ventilation tunnels which are about 1 and 1/2 inches deep.


Sorry if any of this has been covered before, but best of luck
with your project. I know when we took the decision to build it
seemed a daunting task but has turned out to be a truly rewarding
experience.

Paul