F . A . Q

There are several key factors that will affect the cost of your dome.

• • Size of Dome
  • Site Location
  • Materials Sourcing (recycled materials vs new)
  • Foundation (existing or new? Wood deck, packed gravel, concrete?)
  • Intended use (greenhouse, cabin, sauna?)
  • Types of finish (flooring, special door, insulation)

Materials lists for all plans are written in the product description to help you estimate as well!

Cost per Square Foot for a Trillium Dome or Zome 

     In general, construction costs are averaged into price per square foot. For example, in the USA, the average cost per sq ft for a residential building is roughly $150. That means a 1000 sq ft house (quite small) will on average cost $150,000, including materials, labor, permitting, etc. but excluding land. There are many places in the country where the cost per sq ft is 2 or 3x that rate. In this regard, if you are hiring the job out completely, domes are not much different than any other type of construction. 

     If you are interested in an owner-built geodesic dome, there are some average costs in materials associated with our projects. I have found that with the least expensive cover material and foundation (ex. 9 mil woven poly and a gravel ring), the materials can be less than $5 per sq ft. So a 200 sq ft dome such as this can be $500 in materials! 

     That price per sq ft can get even cheaper when you build large domes with a strong yet inexpensive cover like 9 mil woven poly or marine pvc) 

     However, the same size footprint covered in solid clear polycarbonate can be $5,000 in materials! We have found that the cost to build a dome or zome greenhouse with high end polycarbonate covers is generally around $25 per sq ft, exclusively due to the cost of the Polycarbonate.

     A cabin or sauna style dome build tends to be the same in materials as a high end greenhouse, for the shell only. A dried in dome shell is a structure that has a door, windows and roof. Not yet the finished interior or utilities. These are generally also about $25 per sq ft in materials. 

     When adding insulation and finishes to domes, the material costs are generally the same if not less than conventional structures because of the efficient surface area of the building as well as easily repeatable components. We have found fully finished dome or zome structures, with insulation, flooring, appliances, ect. Tend to be around $75 per sq ft. Of course, all these costs vary depending on your location, material choices, and design aesthetic. 

     Each contractor will have their own rates depending on your Trillium Dome project needs. If you are just looking to have a shell built, a safe assumption for a commissioned Trillium Dome is probably $50-$75 per sq ft including labor.

      Easier than it looks for sure, but that is still subjective. Many of our clients have had excellent success with their own builds using our plans, you can see the gallery of their builds here!
      In addition to the plans, the youtube video above walks you through the process step by step so you can get a good idea of the work involved. Be sure to check out our youtube channel for other step-by-step videos for specific builds.

Yes! Geodesic Domes are inherently excellent at dealing with high winds and snow loads. They are known to be the lightest and strongest structures ever devised by humans. Domes with poorly designed hubs or flimsy frame materials, such as pvc or plastic, tend to fold or invert at the joints under pressure. Wood framed domes are superior and less expensive in their design, and can usually boast a minimum of 200 pounds per sq ft load rating. Zomes are even more resistant to snow because of the sharp pitch, no snow can build up! In a testament to their strength, the Antarctic Research Station at the south pole was a geodesic dome for decades, even after it had passed its estimated service life.

Engineering for our designs can be made available by request!

There are many options for many different uses. Look at the properties of these materials versus the cost to make the most informed decision. 

For greenhouses, from least expensive to most:

     Woven Poly Film – This material comes in many different thicknesses and weaves. It is a woven matt, similar to a tarp,  but translucent so plants can thrive. Sometimes they are embedded with strands or fibers as reinforcement. 

• • Used for industrial applications
  • Outperforms normal box store greenhouse film by a mile
  • Highly puncture and Abrasion resistant 
  • Very low cost solution 
  • Easily attached to dome frames (see our Ultimate Geodesic Dome Build Guide)
  • Can be applied in multiple layers with added air gap
  • Extremely easy to replace a damaged section if need be
  • Comes in UV and anti condensation versions

     Marine Grade Vinyl (PVC) – This material is used in the marine industry for its flexibility, strength, affordability and longevity. It comes in different thicknesses and colors. The thicker versions are a solid middle ground between woven poly films and rigid plastics such as Polycarbonate and Acrylic. 

• • Industrial grade material available
  • Less expensive than rigid clear material
  • Highly puncture and Abrasion resistant 
  • Moderately low cost solution 
  • Easily attached to dome frames (see our Ultimate Geodesic Dome Build Guide)
  • Can be joined with PVC cement for a chemical bond between seams
  • Can be applied in multiple layers with added air gap
  • Comes in UV resistant versions, different thicknesses and colors. 

     Twin Wall Polycarbonate – This material is the gold standard for efficiency and strength when it comes to greenhouses. It is extremely impact resistant and virtually unbreakable. The fluted construction adds insulation and durability. It is one of the more expensive cover materials. 

• • Extremely strong (250x stronger than glass)
  • Good insulation value
  • Can be layered for extra insulation
  • Can be attached with glazing tape, adhesive and roofing screws
  • Translucent light scattering good for plants and privacy 
  • UV treated, tinted and colored versions available

     Solid Clear Polycarbonate – This material offers an unparalleled level of transparency, creating an extremely luxurious looking space. It also is a great choice for windows in insulated domes. 

• • Extremely Strong (250x stronger than glass)
  • Can be layered for extra insulation
  • Can be attached with glazing tape, adhesive and roofing screws
  • Crystal clear transparency for excellent views, stargazing, rainy days
  • UV treated, tinted and colored versions available

     What about glass? – I personally don’t use glass, but it is an option. Regular glass is hard to work with, brittle, and quite frankly dangerous. Tempered glass is very expensive because it has to be cut and then tempered, ruling it out for DIY projects. Double glazed type windows would be a good choice for windows in a dome, but the cost is significant. So it is an option, albeit an expensive one.

     For an insulated dome, there are an incredible amount of options to use for covering your structure. The best one for you depends heavily on your budget and climate. In rainy areas, I would suggest using a rigid panel material such as aluminum composite material (ACM), fiberglass reinforced panel (FRP) or a traditional roof assembly such as plywood, underlayment and roofing material. Roofing materials can be architectural shingles, aluminum shakes, or metal sheet roofing with flashing. In arid climates, you can get away with an elastomeric coating over plywood.

      Elastomeric Coating – This material is a good choice for a budget build in an arid climate. I have found that it is not a good long term solution for domes in rainy areas, as the prolonged moisture will eventually degrade the coating. It is an elastic polymer that can be applied to a plywood subroof and covered with an outdoor paint. Multiple coats are encouraged, and maintenance is required often. Unless you live in the desert, I would choose another option.

     Asphalt Shingles – A relatively inexpensive and effective solution, asphalt is a good choice for most any dome projects. A solid roofing underlayment and proper flashing is crucial to ensure a long lifetime. Architectural shingles are highly recommended.

     Aluminum Shakes – My personal favorite, aluminum shakes are incredibly well suited for a geodesic dome roof. Coupled with a high quality Ice and Water Shield underlayment, they create an amazingly long lasting roof with top notch weather resistance. They can be formed in many different patterns for domes and zomes and are flexible enough to bend around facet edges.

     Thermoplastic Polyolefin – TPO is a single-ply roofing membrane that offers excellent performance at a cost-effective price. Heat-welded seams provide superior strength. TPO’s long-term heat, UV, and natural fungal resistance, plus flexibility without need for plasticizers also make TPO a reliable low-slope roofing system.

     Other Materials – Aluminum Composite Material (ACM) and Fiberglass Reinforced Panels (FRP) make good surfaces for dome roofs in many cases as well. They come in sheets of different thicknesses and colors. Additional materials include concrete & sealers, wood shakes, lime plaster, aircrete bricks, and more! Each other these has their own special properties. Their applicability to your project depends mostly on your climate and use of your Trillium Dome.

     The size and purpose of the dome are the first two critical factors when deciding on a foundation. Special considerations around local regulations can come into play as well. 

     For a Trillium Dome greenhouse, usually a packed gravel foundation coupled with some ground anchoring devices, is totally adequate. These are inexpensive and easy foundations to build. The most basic version of this is a gravel ring. You simply dig a trench about 1’ wide 4-6” deep around the circumference of the dome. That is filled with gravel and tamped down. The pressure treated dome base will sit on this gravel ring, ensuring proper support and drainage. The next step up would be a full size gravel pad, which is similar to the ring but the gravel encompasses the whole footprint of the dome. This allows for a stone patio or wood decking to be laid inside the dome as well. Bonus points if you insulate and put radiant heat underneath! The dome can then be tied to the ground via earth anchors. Small concrete piers (think sonotubes) or helical piles can also be set along the dome base to help support and tie down the frame. A wood foundation can also be built and filled with packed gravel to avoid lots of digging.

     Wood framed decks are a great choice for insulated domes, such as Saunas, Cabins and AirBnb’s. They also work great for uninsulated dome spaces that will be occupied by people, such as ceremony spaces and outdoor stages. The decks are typically set on concrete piers, helical piles, or foundation blocks. They can be very well insulated and allow for running to utilities to the dome easily. All Trillium Dome and Zome plans come with the specs for building a wood deck. 

     A concrete pad or stem wall is another option for folks looking to have a greenhouse, work space, or living space dome. Generally the most specialized type of foundation, concrete can be a bit tricky to work with for DIY’ers, and it’s harder to change details or fix mistakes after they happen. There are advantages however. They can be built fairly quickly by a skilled person, are very strong, and excellent at dispersing the weight of the supported structure. They can be embedded with plumbing for radiant heat and insulated as well. If uninsulated, they may keep your dome colder in an unheated greenhouse. 

     An insulated concrete foundation system (ICF) is another good option to look into. 

     Any type of insulation can work on a Trillium Dome or Zome design. The biggest factors are cost and R-value. The higher the R-value, the more effective the insulation. I tend to choose polyiso foam board and spray foam first. But fiberglass batts, blow in cellulose and mineral wool all work as well.

     That is a great question! Building / zoning regulations vary county by county. Your best bet is to find out what zone your property is in and see what the minimum square footage of a structure can be before requiring a permit. Some counties also allow alternative structures with bigger footprints to be built without a permit, such as greenhouses! If you do need a permit, that’s no problem! We can work with you on your specific project to get you what you need to satisfy your local building department.

     Absolutely! Trillium Dome designs can be insulated, heated, cooled, roofed, plumbed and powered just like any other wood framed structure. As you can imagine, lots of factors go into the designing of a living space. Climate, location, materials, size and building codes to start. We are happy to consult with you. Feel free to contact us about your project’s specific needs! 

     Trillium Domes are easily sealed from the rain and the weather with the proper techniques. These methods vary depending on the design, materials used and type of dome being built. See the question above about cover materials for more information on that.

Greenhouse Domes – Film

     When using greenhouse film, the dome frames are covered in groups, expediting the construction process and creating minimal seams. When the frame groups are attached to each other (pre assembly and full assembly) a bead of high quality silicone is added between the wood frames. After the groups are attached (pre assembly and full assembly), a high quality flashing tape can be laid over the seams to create a redundant layer. Our most used tapes can be found on our Equipment and Materials page.

Greenhouse Domes and Windows – Solid 

     This method is similar to film, except there is an intermediate step. After the panels are attached with silicone between the frames, there is a small gap between the polycarbonate or other sheet material. That is to also be filled with a high quality silicone caulk. Then the flashing tape can be added for redundancy, but is optional. This creates 3 layers of protection. 

Greenhouse Zomes – Solid

     The Trillium Zome designs offer a highly efficient way to waterproof without the use of any sealant or taping. Aluminum flashing can be used to lap over each panel like a shingle, creating a cascading effect that is as beautiful as it is effective. See our build video for that here

Insulated Domes

     Trillium Domes Designs can be roofed with just about any roofing material that a conventional structure can. A high quality roofing underlayment is a key part of any good roofing job. Please see the above question regarding cover materials for more information.

     We are currently traveling from project to project via a liveaboard sailboat. Check in with where we are, we may be able to come help you with a project as we pass by!

     If you have the budget to cover travel expenses as well as our rates for site work, reach out! We very well may be willing to travel to you for your project. Our interest will be based on the originality of the project, the location and the budget / rate of pay, in that order!

     We also have a network of verified builders in our Trillium Domes Builders Collective that we can connect you with! There may be someone near you that can make your dome dreams come true, so don’t hesitate to contact us regarding your project. Many people have also purchased our plans and hired someone local to construct!

    We can certainly set you up with someone who can! We have a network of verified builders in various parts of the world as well as the USA. Reach out and we will help you find someone in the Trillium Domes Builders Collective.

      This varies widely between each person! If it’s your first time, I would give yourself a few weeks to make the frame. As you get the hang of it, things will progress much faster! For instance, We can now knock out a 15’ diameter frame in two days! Check out our Youtube Channel to get a feel for the process of each project, as they all differ!

     There are essentially 3 levels of sealing you can do. You can do any number of them and in conjunction they provide a great amount of redundancy in your system!

      The first is to apply high grade silicone sealant between the frames when assembling the dome panels. For film covered domes, you only need to use sealant between the groups of panels you’ve covered with film.                    

    The second level would be to apply high grade silicone or equivalent between the cover material. This only applies to rigid products like polycarbonate or glass. When cutting the material to size (as shown in my ultimate guide to dome building), leave an ⅛” gap so you can have a space to put your sealant in. This is optional for traditional roofing systems because you will want to apply a membrane over the roof substrate anyway. 

     The third is a UV resistant flashing tape over the seams of the panels. For many folks building a greenhouse, this may be the only step necessary. However, if you’re absolutely adamant about keeping water out, the more redundancy the better. My suggested tapes are Pro tape 160 or Siga Wigluv Black.