Been lurking here a while and thought Id jump in head first. Im putting some numbers together to build a residence within a quonset hut. As you can imagine, a quonset hut presents some unique challenges and opportunities. I was considering using ICF for the end walls of the hut instead of their standard metal or stick frame.
 The hut dimensions:
36ft wide, 56ft long, 18 ft peak

The wall square footage of the front is 712 sq/ft, with (2) 90 degree turns, 3 windows and a door
Back wall would be 550 sq/ft with a large opening for the garage doors.
total wall square footage (not including windows/doors) is 1,262

Since the hut end walls are arched Im wondering if ICF is even an option. Ive looked at many ICF web sites and their arches are for windows or door frames, not monolithic arches like a quonset hut would require. Any ballpark quotes on pouring this would be awesome.

Any other questions about the huts construction Id be happy to answer as well.

Thanks guys

-Brad

Posted By socketman on 05 Sep 2011 01:16 PM
 The hut dimensions:
36ft wide, 56ft long, 18 ft peak

The wall square footage of the front is 712 sq/ft, with (2) 90 degree turns, 3 windows and a door
Back wall would be 550 sq/ft with a large opening for the garage doors.
total wall square footage (not including windows/doors) is 1,262

I seriously question the wisdom of your thinking. The roof of the quonset is over 70% of the total area exposed to the the environment. To look at using ICF for only 30% of the area, at undoubtedly quite a bit higher cost, isn't an economical way to go.

How do you plan to insulate the arch portion of the quonset? The fact that it's metal means the main structure of the building provides zero insulating value so 100% of the composite R-value of the arch assembly has to come from the the insulating medium.

How are you going to fasten the interior finish to the arch? If you connect directly to it with bolts then you have serious thermal paths for heat leakage.

In my opinion a metal quonset hut with sprayed foam insulation on the underside is a viable approach for a shop, but not for a residence. A shop requires no interior finish.

Dmaceld,

I too question my wisdom often.

How do I plan to insulate?
Im going to start with 2 inches of closed cell foam through the entire arch. All of it. Then Im going to put up some netting ( or even liner if necessary) that will hold blown insulation, and further insulate the hut to an r-value of 38 or better. (mild climate in the pacific northwest). They sell accessories for quonset huts for just this situation.
Im looking into various latex or elastomer sealers/paints to apply to the exterior of the hut, to help with the conductive nature of metal structure.

Connect the interior finish to the arch?
That is a tougher question. Its difficult to explain without drawings, but essentially im gonna build an arch within an arch using threaded-rod, threaded couplings and metal framing studs. Ive dealt with metal framing enough to comfortable on this front. The "arch in an arch" will hold the sheetrock Im gonna put on.Sounds like alot of engineering for little payout but the material take-off puts me around 1,200 for the entire arch system I would build (not including sheetrock).
My real problem isnt the thermal bridging, or the massive amount of metal. That actually works for me in a way given the climate im in. But i will insulate anyway. My real problem is getting a tight end-wall seal and proper insulation. Hence why i asked about ICFs.

Thanks for questioning my sanity, i do it often. Which is why i read/study/apprentice to improve the skills I will need to pull this off.

I think you would find it easier to use SCIPs (sprayed concrete over foam) or concrete blocks.

jonr,

 i have considered scips, synthetic stucco and various other sprays. The problem is there will be some electrical running through my arch
so i have to be able to access it in case there is a problem. Because scips and other sprays would effectively seal in any electrical Im not sure I can do it. I really got to think about my lighting circuits. i may be able to illuminate things and not run wire through the high arches, just havnt figured out how yet.

The same is not true for my plumbing and HVAC. When you build in straight walls inside an arch, there is a gap left on the sides ( 2-3 ft to be exact). That cavity is where my plumbing and HVAC will be ran (at least most of it). I plan on 8ft ceilings, so Ill have 8 foot of straight wall on the sides and 40'ish feet of arch. The side walls will be in metal stud. I havnt decided if the rest of the interior will be wood. Id really appreciate some pros and cons of metal vs wood. Ive messed with metal framing but am by no means an expert
  The straight walls will allow me to build for seismic code in the normal fashion (shear walls or cross-bracing).

My only real reason for going quonset hut is I can erect the arches myself (with help from friends and beer) and I would have walls and ceilings built into one without paying out for labor. I do plan on renting a boom lift or front end loader to get the arches up. I am going to get a compressor and use impact guns to bolt the whole thing together (sorry this is getting long winded, figured I would explain my plan).
  I will hire an architect (whom ill insist consult a structural engineer) to look at various structural options and get the coveted stamps on the plans.

The main living space will be approximately a 40x40 slab. But the ass end of the hut will only have footers (for the garage area) Then fill in the ass end with a vapor barrier and pea gravel or something. The idea is to save money on the foundation. I only absolutely need slab for the house, not my cars.

Finally, i was weighing my options for the end walls. cement board--rigid foam--Zip board   vs cement board-- zip board only  vs siding--foam--house wrap--osb. There are alot of ways to do it. Which is why i came here to see if ICFs were even possible for end walls.

But if anyone has input on why im insane or what they would do different, I definitely want to hear ideas.

Thanks guys


EDIT: as a side note I should mention im a journeyman electrician, and plan on getting my CBT certificate (construction building technology) in order to get familiar with the other trades. And then shilling out my services for dirt cheap to any company who will hire me so I can get some additional experience.

I assume the slab with be a frost protected monolithic, thickened edge slab? At that point, it might be cheaper to continue the slab through the garage (with a thermal break of course).

Yes sir, Monolithic with thickened edge. No basement or stemwalls or anything fancy.

Its very difficult to figure how much slab I can afford since you generally cant get accurate quotes without the plans.

For now im assuming my garden variety monolithic will come in around 15,000$. Id go a little higher if I could get the entire hut on slab. But I gotta cut costs somewhere.