This is Phillip Young with Arcadian Homes. I am a GC from Mississippi with a degree in Construction Management but not ICF.   This forum has been an invaluable resource to me as a GC and have learned to think "out of the box," as I recently heard someone say. I am in the planning stages of constructing a 3 story ICF house on 18' pilings. I am fairly knowledgeable with the product and know most of the nuts and bolts to standard ICF construction, HOWEVER, what I'm working on right now is absolutely over the top,  literally. The project I am working with engineers and design professionals is this... a Monolithic Hemispheric Dome... on TOP of a 3 story house that is 18' off the ground. It is basically a replica of the Taj Mahal in India.  I'm not making this up. I'm as serious as a deer in the headlights. Not only does it have one central dome, it also has 2 adjacent domes next to it. Kind of looks like Disney World from a bird's eye (isometric) view of the site plan ! I've spoken with an english gent from a California company who constructs monolithic dome homes. He is evidently a good nozzle man when it comes to spraying gunite from a hopper.   He is actually constructing EcoShell structures for the post-Tsunami residents of Indonesia. Anyway, they use an airform technique-interesting concept and yes, I said air, using inflator fans to blow the form up like a balloon) and then applying 1-1/2 inches of polyurethane closed cell foam, imbed a "sticker" every 2 feet apart and then appy another 1-1/2 inches of foam to trap the "stickers"- (def.- a rebar-type chair), and then a birdcage of #2 rebar that is geometrically attached throughout the entire dome area. Shotcrete is then applied at 1/2" increments until there is a solid 3-6" of concrete covering the entire area and then they turn the fans off. The membrane obviously becomes a part of the exterior shell to be finished. The other option would be a composite shingle roof but at a whopping $150,000 quote, I don't think the customer is interested. After I've said all that- now...  is anyone familiar with dome roofs?  I will take all the practical and technical advice anyone has to offer. I would basically have to create a footer at the- 49'-6" top of the ICF wall to tie into the dome. I've read the many threads and the excellent comments on the codes and am familiar with the IRC and IBC stipulations, however, I am working with the engineer that has designed this structure to make sure the plans can get stamped of on all the technical requirements for construction (such things as geothermal, insuldec, and structured wiring). He has actually solicited my advice on techniques for the dome. I've had a couple ideas waking me up in the morning about the design and would like some feedback. My thought is to cut the exterior EPS down to accommodate the air form. I would extend #2 rebar at the top of the 3rd floor wall that could be tack welded to the interior geometrical rebar forming the shell. The airform membrane would be placed between the concrete (maybe a neoprene type of material applied to the concrete first) and a pre-engineered galvanized ring or brackets. The void where the EPS was cut away  then could be sprayed with a closed cell foam and finished with a product like GigaCrete Stucco Max. Does that idea make sense?   I am open to any suggestions.  The schematic cross section of the house shows a passenger elevator shaft constructed of common bond CMU's. All the bedrooms have trey ceilings for the HVAC ducts. I will definetly have Energywise engineer the loads for the mechanicals- (good price and a guarantee- you should use them), flooring is insuldeck, lots of railings (cable and fypon), and I could go on,  but not on this initial introduction. I have been contemplating a few different forms and have reviewed the pros and cons industry comparison charts at ICF Builder Magazine. Any suggestions on the best form for this project? I know Nudura has a radius form but not sure about the others.  I can say with confidence that I have narrowed my search down to approximately 8 companies with a strong attraction to 3 companies. Does anyone have any suggestions on how to collaborate the working arrangement and environment with the HVAC company, plumber, and electrician that will help eliminate serious snags and snafus on this ornately designed structure.   I especially would like to here from someone who is acquainted with Composite or Shotcrete roof applications for this dome and shoring techniques with turnbuckles on the radius walls.  I'm all ears and eager to incorporate any suggestions or techniques into my project . Thanks.

Phillip,

I have a friend who built a dome on his rural castle and it worked great.  He assembled flat shoring several feet below the start of the dome.  He then stacked bails of hay on the shoring platform and shaped it with a gas tamper.  After that he used a plastic sheet and 4" of sprayed foam prior to building his rebar frame.  4 inches of concrete of the top and it still looks great after 15 years.  It seems a little primitive but it works. 

We just installed some of our arch topped steel window jambs in a TF Systems house in Florida in a round stair tower.  I haven't downloaded the pics yet but would be happy to send them to you.

Geoff

Geoff@jamb-it-all.com