We are trying to build, I think, what you call a
> Garden Dome 3 with base
> option in 2 x 4s with twinwall polycarbonate
> attached. This is closest to
> the soccer ball principle, yes?
> I would love to see an image of your connectors (the
> heavy duty ones) and
> see if we can use them.

The Connector Hub system will work well with polycarb
 You can use them for a wood dome, the least expensive
 I would use at least the 2 x 2 wood size for
attaching the glazing.
 For the Garden Dome 3 + Base Option, there are 3
types of Connector Hubs. The Hubs are the Patented
cylinder connectors. You can see at the uspto.gov site
if you have a plugin to see the .tiff file. But they
are simply cylinder sections with holes arrayed
strategically according to dome type. Any plastic or
metal; usually pvc or aluminum.
 A plate method for connecting, would apply to
aluminum domes and cost much more. Could be used with
wood to but the Connector Hubs would be better and
cost less to do.
 The Aluminum Connector Hubs, coated with epoxy paint,
cost around $25 each for a 2 x 4 dome; twice the cost
of the pvc.

 You can size the dome for efficient size for max
usage of the polycarb. If the polycarb is 4 x 8
sheets, 3 triangles can be made from this sheet, to
fit a 22 ft GD3. One of the triangles is a split in
half right triangle like the X1 type, so the polycarb
would need splicing together for this one. 105
triangles/3 per sheet = 35 sheet @ ~$65 sheet = $2,275
for those purchased locally if you are sawing them

 Another good dome for covering with polycarb is the
RCO-S-X1 type, ~20 ft, all right triangles cut from a
4 x 8 sheet with 1 diagonal cut. Flutes can all be
installed up/down orientation with the UV side out as
recommended per installation instructions. 37 "X1"
heavy duty  hubs- $481 + $48 UPS.

 The Garden Dome 3 + Base Option Connector Kit for 2 x
4s with the sch. 80 pvc hubs (61) is $554 + $55 UPS.

What is the height
> of the GD3/12ft dia. at its apex?
Height would be 60". This is proportional for any
Garden Dome 3 dome diameter: height is ~42% of

144" x .42 = 60"

While I'm at it...

The Geodesic Base Option adds 26" to the height; or
13" below the geometric center of the dome.

Over all the GD3+ Geodesic Base Option height is ~59%
of Diameter.

144" x .59 = 85"

A Vertical Base Option (riser wall) made with or
without the extra 15 Base Connector Hubs, could be
made any convenient/practical height and is good for
adding siding to the bottom rectangles, and rectangle
door/ window areas.

Icosa dome info

With 76" struts, [qty req'd = 25]

Diameter is 12.526 ft = 150.33 "

Height is 108.77" = ~9 ft 1/2"

Floor plan / foot print dimensions

3-1/2" are added to the length of the struts, for
Connector Hub size (pvc outer diameter).

Edge length becomes 76+3.5 = 79.5
This is outside edge length, or 2 x 4 strut length +
1.75 each end to Hub centerlines.

The radius of this base pentagon circle is 67.23

Anchor points would be approx. 1.75" inside the
pentagon corner.
But it's best to put together the bottom 5 hubs and
struts, then mark for drill points for your anchor
If you know your anchor bolt size, I can drill a hole
in the Hub bottom to match.
Hubs will point up 26 DEGREES from the level
You can make a short mounting block/ strut for the
bottom hub to rest on, instead of it resting on its
edge. Just match the 26 deg. angle on the block to hub
and 90 deg. at the foundation.

Any other size I can make calculations for easily.

I would like to learn more
> about the Connector Hub
> System for Steel Domes.  The above excerpt was cut
> and pasted for your
> benefit so you know where I am coming from with this
> inquiry.  I don't see
> the connector hub system specially for EMT being
> mentioned anywhere else on
> the website,

I have on my steel domes page, to use Connector Hubs
with these to make stronger domes. This is a theory,
partially based on adding an axial angle to the end
tab bend, so less likelyhood of this connection
"popping in";[larger domes] and giving arch type
strength to the connection with the cylinder hub.

Also the tubes can be screwed in and/ or out of the
hub, which ever works best.
 This method simply adds more bend to the smushed
 tube end, for attaching to the Connector Hub. I made an octahedron umbrella stand
with this method and it works well. It would add the
cost of a Connector Kit to the Steel Tube Dome or Star
Connectors. Would be interesting... never tried yet with a dome.

Is good for glazing, considering difference of inner
and outer struts stacked on a bolt, might be 3/4" to
1" + distance; using big tubes, and 8 or more tubes
stacked ona bolt, like the Octa Dome etc. Smaller
tubes and film cover, not significant.

I came across a
> very obscure information
> about the QUICK CONNECTING FEATURE.  I know that it
> is being mentioned on the
> Connector Kits section of the website, but there is
> no elaboration about the
> feature.

Best is the quick connectors because you only have to
loosen a screw or nut a few threads to take the dome
apart. The Patent shows it on the USPTO.gov sight look
up by #, you have to have a special plug in to see the
.tiff file.
The patent describes lots of optional things, such as
quick connectors and self locking groove in struts.
 Usually on the Quick Connectors, I mix up hub notches
(slide pre-inserted hex head lag bolt into an oval
cutout in th hub; and hanger bolts (studs inserted in
strut with washer & hex nut for conecting hub),
depending on dome type. Most of the connections are
quick connecting, except 1 for each hub that are not.
So you can take the dome apart, leaving hubs attached
to a "permanent" connection, so they will not try to
 For the V groove, it's unecessary although works
good. I recommend instead using a short deck type
screw, 1 per strut. You drill a small hole in the hub,
at an angle to reach from outside and insert the screw
with a drill/driver. So it's easy and quick too and
prevents the strut from swivel action; although this
is not really a problem and optional. Under
consideration is the main attach screws can become
loose from wood drying out, maybe thermal
expansion/contraction over course of months, and
weight such as walking on the struts will cause it to
"swivel". So you can just tighten the screws.
Anti-swivel screw is optional. 65 on the GD2. Much
easier than making a groove in strut ends.

we are new to the dome idea, & aren't sure
> the questions to ask.
> we live in a very windy area of s. colorado, wind
> gusts in spring up to
> 80+mph, also our area has recently been experiencing
> small earthquakes,
> is a dome still an option for us???please advise.

The geo-dome is probably your best option for
aerodynamic. The spray-crete monolithic air form dome
is another option. With the geo-dome, you can also
spray-crete the shell.
 The tall 20 ft Star Dome 2 is near the Air Force
Academy, so gets some high winds and snow. No reports
of any problems.
 Shorter means more wind resistant. Possibly a half
dome on a conventionally built wood frame riser wall,
cement perimeter wall, or Vertical or Geodesic
triangle Base Option, made with 2 x 6, add some wind
breaks and anchor well.
 You can use aluminum connectors for the dome hubs.
You can make inquiries from an engineer about
certification for CO. and a designer or architect for
building plans if those are required.
 I have heard that geo dome have performed well in
earthquakes. They are basically a rigid shell, with
gravity and the earth doing their part to hold it
see - http://www.gardendome.com/sd2c_gallery.html

First I would like to use
> electical conduit instead of wood and wanted a 30-35
> foot diameter finished product. Here in Arizona we
> have termites out in the Desert and I feel wood
> would
> be a problem and then fire too. I want to build a
> metal structure instead of wood. I am too
> considering
> Lexan tented silver on the outside and clear lexan
> on
> the inside to create a thermal pane. Would like to
> know your feelings and again I bought your catalog.

For the steel tube domes, any type and size is
You have some important options for cost
1. Construction - tubes only, stacked on bolts as
shown on
2. Tubes connected to the patented Connector Hubs,
make flat, consistent facial planes, best for
attaching rigid glazing or board panels.
3. Use larger tubes for screwing on glazing or panels,
1-3/8" tubes are a good size.

Use method #1. for lowest cost and thinner tubes 1/2"
- 1" for lightweight covers of tarp/canvas materials.
Use bigger tubes up to 2" diameter for stronger and
larger domes and attaching rigid panels.

Use the fluted polycarb. for best durable and
insulating, lightweight for example

also HDPE as at coroplast.com brand, less expensive
than polycarb.; available in translucent UV for
horticultural uses.

Something like this - 30 ft S.D. 2-C, with sch. 80 pvc
connectors and 1-3/8" steel tubes, galvanized bolts,
ready to assemble, we can do for $7,500 + est. $400
for shipping.
Your covering materials will be extra. The twin wall
polycarb (this is expensive stuff) cover materials
might cost you another est. $7,000 if we saw the
triangles out for you.

You could compare with a wood dome, with the Super
Poly or HDPE  cover, that might cost you ~ $3,500 if
you make it from the Connector Kit. In fact I have a
price for the 2 x 4 Frame Kit + Super Poly Kit Package
Deal, $4,635 for the 25 ft dome, + freight by Roadway
on 2 or 3 pallets. You could build a cement perimeter
wall for a foundation to keep termites out.

 The sch. 80 Connector Kit for 2 x 4 domes, S.D. 2-C,
is $855 + 10% UPS. 76 Hubs and 345 struts - so you get
690 screws with the C.K.

> Could you give me more info and pricing on the 55ft
> dome (please give covering options and price).  Do
> you make any from aluminum and what are the venting
> options.

As a matter of fact I do have a Connector Kit price
for the 6 frequency icosa dome, at $2,205 for sch. 80
pvc Connector Hubs for a 2 x 4 wood dome. There are
196 Connector Hubs. (could be less if shortened)
 Strut lengths would be in the 6 ft range for a 55 ft
dome. Qty. 555.
 I'm making an aluminum dome/sphere with inner and
outer 6061 T6 sheet metal plate connectors, painted
with epoxy coat then urethane over that (for maximum
durability). see
(for reference this 12 ft dome is a $11,000 project;
no covering).
 I would suggest using inner/outer connector plates,
and round tube struts for attaching a rigid glazing at
the various angles. The glazing can simply be screwed
on and cover strip placed over seams between panels
during installation. Use 2-3 wall polycarb. or
coroplast.com type HDPE for glazing.
Outer plates- cut in the star tab design, can be
rounded to conform to the diameter of the strut tube,
attached with counter sunk stainless steel round head
screw. see the 3 ft model
Inner plates - round as shown on the alum. dome page,
attached with aluminum w/stainless steel mandrel
rivets after the dome is assembled with the outer
plates. Acts as reinforcing.
 Venting - custom made windows and fixtures for
exhaust fans. May have a cupola for venting out the
top. May place on a concrete perimater wall with
windows/vents installed.
 About $85,000 for the frame. You would need around
$25,000 of cover materials, a foundation, work crew,
 The 2 x 4 frame kit we can do for $9,500 + shipping.
The Super Poly covering might be $3,000 but I have not
figured up an amount required for this dome.

PS: this dome can be made with round cylinder
Connector Hubs, pvc or aluminum, and round steel tube
struts and cost much less compared to aluminum struts
and connector plates.
Connector hubs will protrude outwardly. Will make
flat, even, consistent face planes for attaching
glazing materials. 1-3/8" thin wall tubes would be
used, as on the 18 ft Octa-Dome (but connected with
round hubs).
This type frame for the 55 ft GD6 would be in the
$16,000 range. http://www.gardendome.com/Gd6.html

> I am just starting to look for a greenhouse dome,
> about 45' diameter.
> I'd like steel struts.  Do you make one that size?
> If so, what would
> other options be,

A Garden Dome 4 type would seem to work well in this
size. It could be the shortened version, that I have
paper model plans for.
 Covering these would be an issue, you would use
polycarb or coroplast.com type HDPE for horticulture;
and probably design the dome size to fit triangles
made from the standard size sheets.
 With this in mind, you need good flat, even triangle
faces for the covering, which can be accomplished by
using the pvc or metal connector hubs, with the steel
tube struts, and add the X1 halving struts.

 I wrote about this just yesterday-
Also with 8 strut ends stacked together on a screw,
may be an inch
difference between inner and outer strut.
 Less so on regular domes with 5 or 6 struts attatched
at a vertex.
If *round hubs* are used [tubes bolted to a connector
hub], all face planes can be equal, or exact and flat
in this
regard. Something to consider. It would add screws,
washers and nuts, 2 per strut, + the hubs, so adds
equivalent to a connector kit to the cost. And hubs
would protrude out instead of in, most likely.
Another advantage is ease of assembly. When building a
typical steel tube
dome, you have to remove the nut to add next row of
struts. Requires 2 or 3
people to do this.  With a Connector Hub, just add a
strut to the Connector
with bolt/washer/nut.  For big/long struts you still
need a helper or
support board to brace up struts/sections during
There is a 9 step process in making a metal tube
strut. -
Measure, saw, smush/bend, punch hole, [drill hole in
star connectors], grind
sharp edges, brush smooth ground edges, wash, paint
bare metal areas. All
but sawing tube sections, is done twice per strut.
For a wood strut, it's
Measure, saw, drill pilot hole, spray on wood
preservative with garden
sprayer (optional)
To make connector hubs, it's
measure, mark, saw, drill holes.
(so steel tube domes cost more than wood domes)
Of course anything worth while takes a lot of effort,
it seems.

> Please forward an application for an individual
> emergency-survival dome
> package.

 Thanks for your interest in the survival domes. It
seems to me that if you are willing to go into the
survival mode of living as a basic survival dome home
would require, then you might should use a Connector
Kit and build your dome and add on amenities as time
and money allows. This would eliminate the shipping
expense (of a large package complete dome).
 For instance the 18 ft Garden Dome 2 type, basic
frame for under $900. With this minimalist approach,
for a few thousand $$ you can have a good safe warm
 Actually I have not succeeded in finding
donation/grant money to underwrite domes to donate.
Only to charity NPOs that can be a tax write off for
me , so we do not have to pay so much to the I.R.S.
 As you can see with the Star Dome 2-C it will make a
nice tough dome plenty strong. This one is in Colorado
in high wind big snow area and has done fine. With
this in mind I have no engineering qualification for
any dome size/type and a general disclaimer as for
implied uses.
 Do you have land with electricity? An alternative is
a small mobile home/rv to use while the dome(s) are
being built.

how does your payment system work? I'm worried about
> spending such a large
> sum over the net. Do you do cash on delivery. Have
> you any suggestions?
> Also, please could you tell me the dimensions of the
> packed items. Are they
> very heavy once packed?

 The Garden Dome 6, I have for $2,205 for the sch. 80
pvc Connector Kit for 2 x 4 wood. Full hemisphere
dome. + shipping 3-4 boxes by US mail (or possibly
freight by boat) possibly 50 lb each. I sent out a box
of 36 hubs and hardware yesterday, was 25 lb. So your
196 hub GD6 proportionally could be 275 - 300 lb. 100
hubs per box, ~ size 30 x 30 x 30 inches.

These domes can be shorter, by deleting 1-3 rows of
hubs and triangles so there is a possible cost
variable there with hub qty.

You can mail a check 50% down payment, with remainer
due at time of shipping, and final shipping costs
detemined then also by final weight and size. It will
take me a few weeks to complete.

Covering with panels made from 4 x 8 ft sheets, all
these triangle panels will be (it seems to me) 1/2
triangles or 90 degree triangles made from cutting the
sheets diagonally, as shown on the Dodeca-Dome page.
So you have to splice the sheets together in the
middle. So it is convenient to have the X1 struts for
the splicing. They could be smaller wood, 2 x 2", and
approx. 6 ft lengths. These would also support the
cover in the large ~ 8 x 8 x 8 ft triangles. This
seems to me the simplest and best way to go.
(another idea is to  use an aluminum strip (thin bar)
or angle, that will not be directly attached to the
hubs or struts).
On the 4-1/2" outer diameter pvc hubs we use for
these, where 10 and 12 struts join at a hub in the X1
domes, the X1 struts have a slight bevel or chamfer on
the hub connection ends.

I would not recommend a large 8 frequency dome. The
mating angles are so slight that the strength of the
spherical arch - grid is reduced. For these type
domes, pyramidal trussing is needed to acheive good

Some modifications will make doors. Example on the 15
ft GD2- http://www.gardendome.com/gd2_gbo_door.gif

Garage dome
 The cylinder connectors are simply tubes with holes
arrayed acording to dome type, size, and wood size.
Struts are sawed at critical lengths and angles I
supply for a certain dome size, with the Connector Kit
 Quick connectors use various hardware and or
slots/holes in the hubs. It is shown on the Patent,
but I don't have the uspto.gov link for it right now.
For typical 2 x 4 we use a 5/16" hex head lag screw, 2
to 3 inches length. Should work for full size 2 x 4s.
Generally the regular pvc connectors, sch. 40 high
pressure type we often use for smaller domes, will
tend to squash slightly under the weight of materials
for 18+ foot 2 x 4 domes, depending on the dome type
and qty of struts, cover etc. So I recommend the sch
80 type that is much stronger and thicker especially
if much cover materials are more than lightweight
tarps or films. Also consider the snow and wind
 This new low cost dome construction method works well
for a wide variety of domes. The Dome Construction
Connectors can be steel or aluminum, but pvc works in
most applications and costs much less.
See also http://www.gardendome.com/sd2c_gallery.html
 The approx 20 ft RCO dome I mentioned might make a
good garage, since you have a bottom square opening
that is about 8 ft x 8 ft. 1 of these has been built
and is in Michigan as a butterfly house.
I made some big images, for the new screensaver. This
one is example, RCO-S[simplified]-X1 in perspective
view. http://www.gardendome.com/Rco_sx1_door_per2.JPG

$475 + $35 UPS for this Connector Kit for 2 x 4, with
the heavy duty pvc hubs.
Make an octagon on the ground with 8 ft boards to get
the floor area.
You might make the lower 8 vertical struts 2 x 6 on
this dome, so you would have 16 longer hubs to fit the
2 x 6s and double attaching hdw = 4 screws for each
 Also take out 2 of the square areas for approx. 16' x
8' opening and possibility of making frame for a
regular garage door.
The screensaver will be $20 on CD, 75 or so drawings,
and extra screensaver of Garden Dome photos included.

> How effective do you think gardendome would be in NH
> during the winter?
> How would the dome not freeze during the subzero
> nights we have here?

The answer to your question is to use
the twin or tripple wall polycarb glazing, or two
layers of film, and heaters as required to maintain a
certain temperature.
 Thanks for your interest. I make geodesic domes of
many types, low cost to high cost, many sizes, various
cover options, some package deals, Connector Kits and
Frame Kits, wood, steel, aluminum.
 Most of my customers use the Connector Kits to make
their own wood domes for whatever purpose. Many are
for greenhouses, with the woven poly tarp (Super
Poly). This makes a relatively low cost greenhouse
with lots of space potential, and a fun project if you
are into industrious work or would like to try it.
 Since one of your goals is for an insulating
greenhouse, the double wall polycarbonate glazing
offers a durable cover with max insulating properties.
You can purchase locally and saw it into triangle
panels (a Rotozip may work well) yourself and save
hundreds of $$. Your polycarb glazing will be the most
coslty part of the dome frame.
 I have designed a pyramid frame that can use the 4 x
8 glazing sheets efficiently with no waste, and
minimal effort. It's the basic Octa Pyramid that can
have a riser wall and add on modular components. This
would be the least expensive but good insulating
dome-like greenhouse with "pyramid power" as a bonus!
Good for 8 x 8 or 10 x 10 ft squarea area, light
enough to pick up and move easily. see
 Using the Super Poly, passive solar collectors can be
used for retaining heat, and removeable foam board
insulation in the windward side; and heaters as needed
to keep interior a certain temperature. Super Poly has
about the same insulating ability as glass.


 On the opposite end of the price spectrum, would be
triangle panel domes made with aluminum frame work and
polycarb glazing pre attached. You would get a crate
by motor freight with several premade triangles ready
to attach together. see

 i'm interested in getting connectors for use with
> pvc struts.  the
> connectors shown on your site seem to be mostly for
> 2x4 lumber. i'm
> interested in building small diameter (5 - 10')
> portable domes for sections
> of my garden and lumber would be too heavy.

The Star Connectors page should hopefully answer most
of your questions.
There are advantages and disadvantages to wood and
steel tube and star connector domes. Possibly, a 2 x 2
wood dome may be low weight and strong enough for you
and less cost than the Star Connectors. Depending on
if you want to saw the wood with a miter saw, or just
pvc with a power saw, or tube cutter.
 Some smaller complete steel tube domes can be shipped
by UPS in 1-2 boxes. As I mention, there is more work
involved cutting and drilling, to make Star
Connectors, VS. the complete steel tube strut dome.
But it seems the advantage of the Star Connectors is:
1. Make your own struts from pvc or other material
2. Light weight
3. Easier to apply covering to pvc or wood struts
4. Resizable by proportionally resizing the struts.
5. Will never rot.
6. Strong yet flexible (depending on strut materials)
7. Easily and quickly assembled and dis-assembled

GardenDome 2
Thank you for you Connector Kit order.
Let me know what diameter size dome you plan to
build. For reference, using maximum of board length
for 8 ft boards-
dome diameter is ~15 ft for sawing two struts per
diameter is ~26 ft if using 1 strut per board.
If using 10 ft boards, and sawing two struts per
board, max diameter is ~18 ft. These sizes will give
you less board waste (and more dome for your money)
but any practical size can be made.
Below I try to describe Base Option types, that have
different connectors. My own recent dome project shows
the Vertical Base Option method. -


> 1. Geodesic. All triangles. \ & / struts must be
> length close to the others, but it is variable to a
> degree. A door method would be 2 hinged triangle
> panels or a 1 piece flap entrance if film is used
> covcering.

> 2. Vertical. All rectangles, with intermediate
> vertical
> struts as required to give stability, and variable
> height from approx. 1 to 8 ft. Best for use with
> siding. A standard door can be used if tall enough.
> Door can be as with option #3-

> 3. Geodesic, with vertical struts for door retrofit.
> hubs are modified to make an "A" frame. A flat "A"
door can then be built,
> for a hinged entrance. (smaller domes; larger ones
can have a standard door, see
http://www.gardendome.com/gd2_x1a/gd2x1a_door.html )
> I will make the Connector Hubs according to the Base
> Option type you want to make.