billnaegeli
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| 02/03/2008 8:32 PM |
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according to the 2003 IRC, ICFs can only go one story above grade w/o additional engineering, i have been told only Integraspec is ICC rated to go 2 stories above grade w/o the additional engineering expense. i have also been told that the "Prescriptive Method" has some descrepancies in it as well. would like to hear from some "professionals" on this issue, especially since we are getting alot more houses being built with these and we are going 3 and 4 stories above grade with them(3 stories above grade for any beach house)
1- what is an authority publication we use for local building code offices
2- why is there limitations for one story for "most" ICF blocks
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icfcontractor
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| 02/03/2008 8:44 PM |
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Bill,
Question 1. It depends on where you are located. CA has their own code, some states use the UBC, some states use the IBC and IRC, some jurisdictions use their own code that is an amalgamation of many codes. Some jurisdictions will accept the HUD perscriptive method and others won't.
Question 2. I believe this is a function of the IRC and companies willing to do the minimum asked of them. But this is only a guess. Where I build the ICC carries very little weight and the building codes take precedence.
This is my experience,
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dmaceld
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| 02/03/2008 9:17 PM |
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Posted By billnaegeli on 02/03/2008 8:32 PM
according to the 2003 IRC, ICFs can only go one story above grade w/o additional engineering,
From the 2006 IRC:
R404.4.1 Applicability limits. The provisions of this section
shall apply to the construction of insulating concrete
form foundation walls for buildings not more than 60 feet
(18 288 mm) in plan dimensions, and floors not more than
32 feet (9754 mm) or roofs not more than 40 feet (12 192
mm) in clear span. Buildings shall not exceed two stories in
height above grade with each story not more than 10 feet
(3048 mm) high.
What I have read of the IRC requirements they seem to pretty much copy the Prescriptive Method requirements. I've not done a detailed comparison but I haven't seen any conflicts between them. I don't recall the specifics now but I think Polysteel design requirements are stricter than the Prescriptive Method. I used Polysteel manual for guidance and reference even though I'm using BuildBlock. BuildBlock has adopted the Prescriptive Method. My civil engineer cousin gave me a thumbs up on the footer design, and the BI didn't have any quibbles (except asking about flammability of the XPS covering the footers) when he gave me the Building Permit.
I should have quoted this section:
R611.2 Applicability limits. The provisions of this section
shall apply to the construction of insulating concrete form
walls for buildings not greater than 60 feet (18 288 mm) in plan
dimensions, and floors not greater than 32 feet (9754 mm) or
roofs not greater than 40 feet (12 192 mm) in clear span. Buildings
shall not exceed two stories in height above-grade. ICF
walls shall comply with the requirements in Table R611.2.
Walls constructed in accordance with the provisions of this section
shall be limited to buildings subjected to a maximum
design wind speed of 150 miles per hour (67 m/s), and Seismic
Design Categories A, B, C, D0, D1 and D2. The provisions of
this section shall not apply to the construction of ICF walls for
buildings or portions of buildings considered irregular as
defined in Section R301.2.2.2.2.
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Building house - what a way to spend retirement! |
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James Eggert
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| 02/03/2008 10:22 PM |
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| I agree, the IRC2003 allows 2 stories above grade! |
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Take Care
Jim
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"Not So Big" Design Proponent |
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Farmboy
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| 02/04/2008 2:36 AM |
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May I ask for clarification? "...Buildings shall not exceed 2 stories above grade...." So by definition of a storey you must have a diaphragm/floor above the first storey and a diaphrgm/roof system above the 2nd storey? And not go up 20 ft without tying the walls together somehow?
Several of the ICF block companies (Logix and Arxx for example) have above grade walls tables that go up to 16' for 6.25" walls and 20' for 8" walls. I didn't see any reference in those tables about a 2nd floor/storey. Are these tables for freestanding walls up to 16' to 20' as long as you meet the minimum rebar schedule for various wind speeds?
Learning all the time. Dave |
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dmaceld
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| 02/04/2008 10:05 AM |
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That's not the way I would define things. It's always been my understanding story is measure of height. If you have a house with 20' high walls and open roof/ceiling design, open all the way from the ground level, i.e., one floor only, it's still considered a two story house. A house with two floors with a finished attic space fully contained within the rafter space of a steep pitched roof would be considered a two story house even though you have three living levels.
Now, since I haven't spent my life in the building industry I could be misunderstanding things, but this is the way I've always heard it discussed.
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Building house - what a way to spend retirement! |
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icfcontractor
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| 02/04/2008 10:49 AM |
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Farm Boy,
The IRC defines a floor as (R 202) "That portion of a building included between the upper surface of a floor and the upper surface of the floor or roof next above."
In reading the Logix tables they refer to 3 picturse on the next page in the notes and these are two story buildings. So I would interpret the table as a one to two story wall to the max height of 20 feet. But bear in mind this is just the wind load tables. |
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Farmboy
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| 02/04/2008 11:04 AM |
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Dmaceld. Based on your many thoughtful inputs I'd say you've a good grasp of construction topics.
Just rvw'd the HUD Prescriptive 2e. Says "Storey: That portion of the building included between the upper surface of any floor and the upper surface of the floor next above, except that the top-most storey shall be that habitable portion if a building between the upper surface of the top-most floor and the ceiling or roof above."
So if a Logix or Arxx table (and maybe others) show WALL heights up to 16 to 20 feet, are these wall heights intended for full height ceiling, i.e., cathedral look, etc? Where you wouldn't have an intervening floor? I guess I'm really asking how high can you build free standing walls? Dave
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Farmboy
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| 02/04/2008 11:09 AM |
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| ICFContractor. Just read your post. Verifies IRC and Prescriptive match in this regard. So I hear you say a one storey height of 20 feet is possible, if you meet the rebar sched within your design windload!? Seismic requires engineer design. Thanks Dave |
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icfcontractor
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| 02/04/2008 12:58 PM |
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Farmboy,
I believe this will work. We have done several shops with 15 and 20 foot ceilings.
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dmaceld
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| 02/04/2008 5:57 PM |
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OK, OK, so I wrote without reading the official definitions!!! Allow me to back peddle and change course a little bit. A two story house has two floors. A two story tall house might have only one floor!! Ah, forget it. We all know what we're talking about!! You got the reassurance that, yes, you can build a 20' high ICF wall. That's what matters.
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Building house - what a way to spend retirement! |
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icfcontractor
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| 02/04/2008 10:36 PM |
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dmaceld,
In the immortal words of Jeff Spicoli, "Don't worry dude, my brother is a TV repairman."
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James Eggert
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| 02/05/2008 8:28 AM |
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Also keep in mind that some ICF companies have already done the engineering which may exceed the minimum standards as set by the adopted codes.
This is why many people should deal with a designer/architect/engineer, whomever, that will interpret and help get to a safe end result! Some people can wade thru the tables and legalese and many times your local building official can help, however, do not go in expecting the AHJ to design your problem areas for you...you need to be prepared before you show up and say this is what I want to do! |
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Take Care
Jim
Design/Build/Consulting
"Not So Big" Design Proponent |
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