What wall assembly would YOU use?
Here’s a design for a current client. Click for larger image:
View Image View Image The goal is to mimic a brick colonial, but with the advantages of the insulated concrete structures I typically do. The vertical walls are insulated concrete and dome-shaped air forms are attached to the top, inflated, and sprayed with foam insulation and then concrete to create an integrated insulated concrete house. The question is about the vertical walls. I specified them as TridiPanels (a foam panel with welded wire reinforcing that’s shotcreted on both sides to about 2″ thickness). A 4″ x 12″ “beam” would have to be formed at the top the the wall to handle some of the loads from the inflation of the air form. Finally, the exterior would be finished with veneer brick. The brick has no structural purpose, so veneer should be cheaper, quicker, etc. Running into some disconnects between builder(s) and suppliers. The tridipanel mfg talks about the economy of his product. One builder, for example, says that the labor and shipping for those will kill him, and wants to build a full brick wall, shotcrete the inside, and then foam and shotcrete inside that. I can’t imagine that’d be cheaper, but he says it would be. Others have other ideas. Everyone wants to try different approaches from each other, not because the original plans won’t work, but because what I’ve drawn is new for them and they seem to be reverting to whatever is most familiar for them. So, I’m curious. How would YOU want to build those walls? Would formed and poured be faster? Would ICF be easier…how’d you brick ICF? Just searching for alternatives since encountering some unexpected resistance to the tridipanels. Also looking for something that a local contractor could do prior to bringing in the dome guy from out of town. Any ideas?
Edited 2/10/2006 11:26 am ET by CloudHidden
Replies
Here's one alternative I'm looking at: http://www.dow.com/styrofoam/na/pouredinplace/performance.htm
It uses conventional pour-in-place forms and puts the insulation in the middle. Could use a local former. Any guidance of "typical" fees for forms rental or using formers? Always done spray-in-place stuff, so never had reason to use that sub.
CH
You are probably going to have trouble finding anyone who has experience with both the Tridpanel and ICF who can discuss the pros and cons intelligently.
Adding brick to an ICF job is child's play. Most manufacturers sell a special brickledge form which can be added at any height, though you will probably have to modify the height of your starting course to adjust the brickledge height. These forms curve out from the outside wall to the vertical plane of the brick. They are slow to install as the corners have to be hand mitred and there is a lot of steel to place in them.
ICF walls can take quite a lot of side loading, and the load limits can be increased by adding more steel in the right places. Most manufacturers have pre-engineered the forms to take backfill heights to 12', but with a floor installed at around 9 or 10. The side thrust of the roof might be an issue, but not more than with another of the wall systems you have been thinking about.
I think the main point is that ICF construction is easily within the capacity of any good carpenter and choosing ICF might make scheduling the job easier in that you would be able to choose a builder from a larger pool.
Ron
hi, ron.. thanks for Old Glory.. what a writer !
cloud.. of all the options mentioned and the idea of energy conservation, i like the icf approach..
and you can use some interior concrete walls ( non -icf ) tied to the exerior as buttresses to prevent wall spread.. although i tend to think your domes /reinf/shotcrete are probably self-restraining anyways , once they are cured to design-strength
BTW.. i've never built an icf structure... Mike Smith Rhode Island : Design / Build / Repair / Restore
This form is very similar to the system used by this company.
I always find the idea to be simple and strong. Would seem to work well with your product/system.http://www.allwallsystem.comPete
Thanks, that's one I had not seen. I see it's essentially a concrete post and beam structure. I was surprised that the concrete posts and beams don't have a worse effect on the energy usage than they indicate, since there is no thermal break there.
I have to imagine that there would be lateral force onm the walls unless the domed cap is self restraining, which I don't know.
But if there is lateral force applied from the roof base, then you need a desiogn that resists outward spread. In that case, I don't believe that the brick with shotcrete will do much goood.
I don't have any idfeas or knowledge about triflow.
My first thought was the ICF walls with lots of rebar and possibly a cabled restraint system. Brcking the outside of ICF is easy. There are plenty of connections to screw brickties into.
Maybe this will at least bump you into more attention and responces.
Interesting concept.
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>unless the domed cap is self restrainingIt is self-restraining, with some exceptions, but the engineer has a good handle on those.The dilemma is in figuring out which wall assembly is most affordable for the client (thought we had done that, but possibly not). Before we can get valid estimates we have to have suitable plans and engineering, of course, but it's not easy to prepare plans for each of the numerous options just to get a reasonable estimate. And it's frustrating to run into disconnects between mfg guidelines on cost of construction using their product(s) and the builders' actual estimates. Some might be over-zealousness by mfg, some might be risk perception by builder, some might be... Combine all of that, and it's hard to advise the client.Another challenge I face is that cost expectations are so different from what some of y'all seem to encounter. Mike's current job is coming in at $185 or $225/sf or whatever. For all of the detailing we've designed into this one, and all of the new configurations we were incorporating, it was still coming in close to $150/sf from a highly qualified contractor. It's a PR problem...not dissimilar from what frame builders probably face if they quote a price for custom and the client says, "but there's a development down the road giving me 3000 sf for $299k."
Cloud,
I can still install an ICF wall for C$13/sf plus footing cost despite recent price increases. Don't make any deductions for window or door openings. Add a bit to be safe. Wall heights greater than 11' will probably demand a second pour.
Logix ICF recently reduced the price of their product. It is now C$3/sf plus shipping from the factory, which will add C$0.25/sf or more for a full load of 4000 sf or so. Maybe they are pushing it as a loss leader, maybe they need some quick cash, maybe they can sell for significantly less than everybody else and still make money. I dunno.
Ron
I've learned a lot about Thermomass, or Dow T-Mass walls in the last few days. It could save the project. The client is super-excited. Someone coincidentally started a thread just as I was researching it: http://forums.taunton.com/tp-breaktime/messages?msg=69621.1Ron, was your $13 Canadian or US? Let's see, multiply by pi, carry the 2.....that'd make it?The T-Mass is projected at $15-$16/sf installed. But comparing that to ICF, there's no need to sheetrock inside or stucco/side the outside, so the costs get a lot closer, and maybe tip toward the precast. Close enough to not make a diff.What I'd like is to have y'all take a critical eye toward the T-Mass walls and help identify any flaws in the assembly. Anyone think of a reason why they wouldn't make an awesome wall? Why something else is better (not just for my app, but in general)?
Cloud,
Canadian dollars. I'd like to whisper this so as not to start something I want no part of (((I think American costs for a company similar to mine might be higher because of the higher cost of carryign medical insurance down there )))
Interesting wall system. I'd like to see one.
Ron
>Interesting wall system. I'd like to see one.Come for a visit to NC...there's a model house using it right down the road a bit at the manufacturing plant.
Ditto what Piffin said.
I'm only familiar with ICF construction so can't add much to your roof situation.
Also, some of the interior walls could be ICF to help resist outward pressures from the roof, or some kind of connectors would need to be set in the concrete to attach to wood interior shear walls.
Don
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