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tb1472000
Registered Users
Posts:13
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| 04/03/2008 3:51 PM |
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Does the 60 feet in R404.4.1 mean that the building can't be wider than 60 feet or does it mean no wall can be longer than 60 feet? I.e. Would a house that had say a wall running East/West 50 feet then taking a North/South turn of 2 feet and going back East/West 50 feet fall within R404.4.1?
Thanks,
Bruce
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.
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James Eggert
Registered Users
Posts:1001
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| 04/03/2008 7:30 PM |
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| The 60' is a max run which can be 60' x 60', however floor joists clear span cannot exceed 32', and roof rafter clear span cannot exceed 40' per the 2003 IRC commentary |
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Take Care
Jim
Design/Build/Consulting
"Not So Big" Design Proponent |
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robinnc
Registered Users
Posts:115
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| 04/03/2008 7:39 PM |
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You also might want to talk to the local ispecter since s/he will be the one approving it.
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PanelCrafters
Registered Users
Posts:1329
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| 04/03/2008 7:54 PM |
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Posted By tb1472000 on 04/03/2008 3:51 PM
Does the 60 feet in R404.4.1 mean that the building can't be wider than 60 feet or does it mean no wall can be longer than 60 feet?0'
What it really means, is that you can't exceed the 60' w/o requiring the structure to be engineered. |
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....jc
If you're not building with OSB SIPS(or ICF's), why are you building? |
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James Eggert
Registered Users
Posts:1001
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| 04/03/2008 8:06 PM |
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jc
good point! |
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Take Care
Jim
Design/Build/Consulting
"Not So Big" Design Proponent |
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tb1472000
Registered Users
Posts:13
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| 04/03/2008 8:53 PM |
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That is what I thought, but was hoping otherwise.
Thanks,
Bruce |
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James Eggert
Registered Users
Posts:1001
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| 04/04/2008 8:30 AM |
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however, after a run of say 58' and a corner and/or buttress, you should be able to continue on.
The IRC does not establish square footage, but simply says a max of 60' for a run!
This still is not saying 180' with 2 corners, I'm only saying there is some practical flexibility
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Take Care
Jim
Design/Build/Consulting
"Not So Big" Design Proponent |
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walltech
Registered Users
Posts:469
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| 04/04/2008 8:51 AM |
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Unfortunately I have run into this a few times with our customers. The code interpretation shows a maximum of 60' in length and never even clarified whether that included the garage if one was present. Practical sense would dictate the house foundation only, but has been interpreted as total foundation length by some. The codes for IRC where taken from Prescriptive methods 1, now that PM2 has come out and dropped the 60' rule you may convince you BI that a 60' length is not applicable any more.
But with caution you should get advise from a professional as to your soil conditions, back-fill height, wall thickness and make sure what your trying to achieve is favorable.
Dave |
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wes
Registered Users
Posts:376
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| 04/05/2008 8:54 AM |
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| Does this 60' rule not mean a clear span wall with no shear walls? |
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Wes Shelby
Design Systems Group
Murray KY
wandr@ainweb.net |
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walltech
Registered Users
Posts:469
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| 04/06/2008 8:06 AM |
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Wes, the IRC commentary only shows a box 60' long, it doesn't have any allowance for shear walls, corners, or seperate structures like a garage addition.
Dave |
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James Eggert
Registered Users
Posts:1001
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| 04/06/2008 5:54 PM |
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| It means a floor span cannot exceed 32', nor can a roof span exceed 40" |
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Take Care
Jim
Design/Build/Consulting
"Not So Big" Design Proponent |
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Chris Johnson
Registered Users
Posts:341
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| 04/06/2008 6:43 PM |
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I love the building code....and the million people or so who try to interpret it.
My take
60' max continuous run without interuption (corners, bearing walls tieing in, etc.) i.e. do a run of say 62', you need a butress.
so that being said, built 120' of wall and throw in an offset (3' 90 corner) and you fall back within the scope of the code
If you don't fall within the perimeters have it designed by an engineer
Didn't we do this discussion a few weeks ago with the height issues? |
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Chris Johnson - Pro ICF
Napa, CA
Come for the wine, Stay for the ICF work |
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dmaceld
Registered Users
Posts:494
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| 04/06/2008 10:51 PM |
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As has been said, the 60' limit comes into the IRC from the Presciptive Method, 1st Edition. Here is a quote from the body of PM 1.
"The provisions in the Prescriptive Method apply to detached one- or two-family dwellings, townhouses, and other attached single-family dwellings not more than two stories in height above grade. Given the maximum building plan dimensions and the roof and floor clear spans specified in Table 1.1 of the Prescriptive Method, the largest rectangular home that can be constructed without a center load-bearing wall or beam is a home 40 feet by 60 feet (12 m by 18 m). The largest rectangular home that can be constructed with a center load-bearing wall or beam is a home 60 feet by 60 feet (18 m by 18 m) provided that the roof and each floor is supported by a center load-bearing wall or beam to reduce floor and roof clear spans. Application to homes with complex architectural configurations is subject to careful interpretation and sound judgment by the user; design support may be required."
As you can see, the largest simple design house can be 60' x 60'. Beyond that you can argue that there is no limit as long as "careful interpretation", "sound judgement", or "design support" is utilized. Individual wall lengths and heights will be limited by the requirements to satisfy seismic, wind load, snow load, etc., parameters for a specific area. In other words, you can design a larger unbraced wall for an area with a prevailing wind of 50 mph with an exposure category of B than you can for an area with a prevailing wind of 90 mph with an exposure category C.
As Dave said, PM 2 dropped the 60' limitation. However, if you read Appendix B to PM 2 you will see that 60' is the max length used to develop the other limits and criteria such as max wind load of 150 mph and two stories above grade. Taking that into consideration you can easily argue that you should be allowed to build a single story wall in a wind zone of 90 mph somewhat longer than 60'. The 60' limit is still pertinent which is probably why it is still in the IRC.
If you can show a building official that your proposed wall design is stronger than the simple unbraced wall of 60' x 2 stories, you should be able to get his/her buy in. As in all things related to code interpretation, the more rational and documented your story is, and the more open minded the BO is, the easier it will be to get approval.
In short, if you are going to rely on the values prescribed in IRC 2006 to show your design is adequate, then be prepared to show that you don't exceed those values by having a wall greater than 60' long. For example, you have two walls connected by a third perpendicular wall mid way, (in Z fashion). If the connecting wall is 30' long you can easily see how it would provide greater lateral support than if it were only 5' long. With the 30' connecting wall each of the other walls can be longer because the resistance to perpendicular wind load would be greater.
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Building house - what a way to spend retirement! |
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