mark pecora
New Member
Posts:4
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| 22 Feb 2007 10:04 PM |
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Anyone have any neew info on poured concrete roof systems? I am aware of Amvic and LiteDeck. Has any builder had any experience with a company called HPRS ( www.hprscorp.com)? They advertise a poured concrete roof which is attached during pour to extended rebar from top of wall system, calling it a monolithic pour. Anyone with any information or input on this or any other concrete roofing system is appreciated. |
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ICF372
Basic Member
Posts:111
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| 24 Feb 2007 02:42 PM |
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Mark, Well they have a rather flashy website, and it looks like they are ready to take your money for franchise. It appears to be another foam slab that you pour concrete on top of . Can't really tell, I could not get any details. You did not mention ARTFORM it is the only ICF roof system I know of. It requires no shoring and uses a standard icf form along with speed floor joist. A good option to vaulted concrete roofs is a flat speed floor ceiling with frame roof above . Much cheaper and with all of the advantages of a ARTFORM roof system, other than you will need to add foam on top of the concrete. |
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Eldon Howe<br>Howe Construction
[email protected]
<br><br>Total Concrete Homes provide positive cash flow , DAY ONE . |
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Opus
New Member
Posts:68
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| 24 Feb 2007 06:02 PM |
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I had seen the HPRS web site and got a chance to see the actual product at the International Builders Show a couple of weeks ago. It seems to be a nice system. My problem with it is the issue of thermal bridging. You have steel and/or concrete running from outside to inside. Any insulation in between the bridging becomes very ineffective. You do not have that problem with Amvic, Insuldeck or Litedeck. Of course that is an issue the can be addressed by creating thermal breaks and adding furthur insulation - resulting in more expense.
C. Perry |
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James Eggert
Basic Member
Posts:411
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| 25 Feb 2007 01:03 PM |
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I have not looked at the product in question, but have a comment on thermal break(s).
If a product is not designed with a thermal break, it could be for two reasons, they didn't plan or want it...or....they didn't feel it was necessary.
Review thermal breaks carefully. If there is a large thermal mass around the thermal "bridge", the temp changes are not just direct like a hole, it needs to also change the thermal mass immediately around the metal which takes quite a lot more time and slows down any purported thermal bridging.
It's not as simple as "If I have metal, I have a thermal break!" |
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| Take Care<br>Jim<br><br>Design/Build/Consulting<br>"Not So Big" Design Proponent |
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woulfcc
Basic Member
Posts:147
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| 25 Feb 2007 11:07 PM |
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Jim good point, i see what you are saying. Thank for opening my mind on that.
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| Changing How the World BUILDS!<br>Green , Done , Easy<br>Woulf c.c. of Wisconsin |
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Opus
New Member
Posts:68
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| 25 Feb 2007 11:36 PM |
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Jim,
I would have to respectfully disagree with you on this issue. A third reason to leave a thermal break out of a system is the difficulty in creating one and a lack of understanding as to how much heat can move through a small steel section. If you look at the Oak Ridge testing (http://www.ornl.gov/sci/roofs+walls/AWT/HotboxTest/LennarSteel/index.htm) you can see that using a steel stud every 24 inches drops the R value of a fiberglass insulated wall from R13 to R 6. That is a rather dramatic heat loss/gain. Having a large thermal mass on one or both sides of the roof insulation presents the possibility of decreasing the average temperature differential ( the Delta T) between the two sides . This would of course reduce the loss or gain but the fact remains that with steel runing from one side to the other the loss or gain could easily be double for a system with no thermal break. The HPRS has a concrete mass on the exterior. In Florida that means a roof temperature of 120 or more that can be held long into the night. In this case the exterior thermal mass creates an even greater Delta T and thus a greater heat gain. A reflective roof coating helps but the fact remains that any system with steel as a thermal bridge is going to perform much worse than one with a good break. My personal thinking is that at this point in time energy efficency is of great importance and I would not consider any system with steel thermal bridging in any situation.
C. Perry |
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James Eggert
Basic Member
Posts:411
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| 26 Feb 2007 09:04 AM |
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We can disagree because we are saying two different things, albeit both about thermal bridging.
Again, I have not reviewed the HP system, my comments are expressed in their simple form as related to thermal bridging.
I can agree with the Oak Ridge analogy of the metal stud wall, using fiberglass insulation. No argument there, poor insulation, no thermal mass, no or little protection for the metal studs, etc. That's how I used to build commercial buildings in the Northeast because that was how the archy designed them. Very similar to the metal can buildings which are ok for warehouses, but have a lot of problems when you want the office areas!
Now, taking an ICF block with metal ties, which is where my comments are based, the possible thermal bridging when there is such a large thermal mass(concrete) around it, performs very well. In fact, although it can be measured with scientific equipment, it has no basis in real every day life. No one will notice the difference of such a miniscule variation. By miniscule, I mean instruments versus real life touchy feely! A good example would be the older, but still available Polysteel metal stud ICF blocks. That is my comparison for block thermal bridging.
I am not reviewing roof structures for thermal bridging and then how to keep the structural integrity intact because I don't have time. I'm also not saying these type of roof systems are good, bad or whatever!
Metal and thermal bridging with concrete mass in general to me means measureable but probably not an issue for day to day useage. The metal stud wall was always a wasteful construction technique! |
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| Take Care<br>Jim<br><br>Design/Build/Consulting<br>"Not So Big" Design Proponent |
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mark pecora
New Member
Posts:4
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| 26 Feb 2007 07:14 PM |
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Thanks to all who had info on roof system; I am considering many things as my family and I progress towards building an ICF home in Florida. No, I am not a spokesperson or future franchisee of any of the products on this or any other forum, but I want to learn as much as possible so that I can make the most informed decisions I can. Thanks to all of those who participate in this, as the forums give a lot of insight into the issues/problems which are often not mentioned in a manufacturers or builders brochure.
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