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Roof snow loads
January 18, 2006
10:33 am
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richardr
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In our county we have broken it down by elevation going from 20psf all the way up to 50psf for the highest parts. Our county has elevations from about 3000ft to 7000ft. where homes are being built.

January 18, 2006
10:29 am
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jj1289
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CT did away with the map and added an appendix the lists each municipality and the minimim ground snow load, wind loads and seismic loads.

January 18, 2006
9:44 am
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cny elevator consultants
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NY put together its own map, for comparison: Ground Snow loads: most of the southern border with Penn. is 45psf, with some max. of 65 along the shore of Lake Erie. Syracuse, which averages 200 inches of snow a season is listed as 55, and the nearby Tug hill area is 85! Buffalo: 50, Albany 65, Rochester 50, NYC 45. There is also a NY enhancement that allows for a caluclation by the local AHJ to use other loads where necessary.

January 16, 2006
12:51 pm
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jar546
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PA should do the same thing as Michigan

January 15, 2006
6:50 pm
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peach!!
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In Michigan, the state has made a clearer, state specific map.. (I say clearer, because most areas are very clear.. around the Lake Michigan shoreline, it''s pretty general.. some jurisdictions go from 30-60 gsl, and it''s really up to the building official to determine where the boundary is.. ) in our case, generally west of US31 has the higher snow loads.. (lake effect)

January 15, 2006
11:05 am
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jar546
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Thanks STB, much appreciated. I ended up having to call each individual municipality. I wish they has this information listed on a website.

January 14, 2006
10:15 am
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stb
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jar546,

Figure R301.2(5) footnote a. states that the Case Study is done on an individual basis. It is the applicant''s or the Builder''s responsibility to supply a snow load to the building inspector. When the I codes were first adopted in NE PA, we chose to use the snow load of 50 as a default, since it roughly equals 38.5psf design load and we allowed a 30psf design load under our old code. After receiving much flack from the contractors, I had a study done on the the 2 areas that are being heavily developed and suprisingly enough the study came back at 55 and 60 psf. The complaining seemed to cease after that. FYI, the DCED of PA has put the Pocono area in 60, thats what all modular homes must be designed to.

December 28, 2005
8:54 am
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jar546
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I have found that many municipalities have their snow loads posted on their websites. Many are 30psf but Scranton decided they are 35psf. If you go farther north and east the snow is worse so I would expect higher loads, the map is not broken down far enough . Without lines on counties it is a waste of time

December 28, 2005
5:37 am
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new guy
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jar546 - When the UUC went into effect, I simply enlarged IRC 2003 Figure 301.2(5)a number of times in order to discern exactly where my municipality was actually located.

When I determined its location was actually in a "25 psf zone", this was a challenge since the IRC 2003 Code Book did not include 25 psf Tables.

Instead of having everyone rely on various resources to determine 25 psf rafter span calculations, (I used the internet site "Span calc" at that time), I convinced the Borough Council to approve a more robust value of 30 psf for Table 301.2(1), so the Code Book Tables 802.5.1(3) and (5) could be used for typical construction.

December 28, 2005
5:08 am
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crcasteve
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sp_Print Print Post Post #10

30# here in Centre County Pa
I have had alot of contractors tell me some horror storys from the maddness that is the state wide code.. We have been enforcing boca since 1968 then moved to 2000 I-codes, then got a look at what the state did to it.. it''s a mess. Its funny it was a running joke that some contractors would not work in the Centre Region because of the CODE, now its changed now contractors say they won''t outside the Centre Region.

December 28, 2005
4:43 am
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spanky
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You have to understand that Pennsylvania just recently adopted a statewide building code. There is alot of confusion about many things as far as code enforcement goes. It seems like every municipality is doing whatever it wants, they just invent rules as they need to. I guess eventually the State will get it right? Here in Bucks County in the lower eastern part of the state the snow load is 30 psf, but if your town is located in the poconos or the western end of the state the snow load will increase. Check section R-301.2(5).

December 28, 2005
4:15 am
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paul sweet
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sp_Print Print Post Post #12

The Army Corps of Engineers Cold Regions Research & Engineering Lab http://www.crrel.usace.army.mi.....index.html developed the snow load map that is in ASCE 7 and the IBC & IRC. They developed a procedure to calculate site-specific snow loads: http://www.crrel.usace.army.mi.....MP5008.pdf
They applied this procedure to determine snow loads for 140 towns in New Hampshire, and said it took about 2000 man-hours, so I would imagine it would take a lot longer for Pennsylvania (or Virginia). Maybe an engineering professor who has a lot of students with too much time on their hands could make this a class project.

December 28, 2005
2:57 am
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tomw702
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sp_Print Print Post Post #13

Try taking a look at Figure R301.2(5) of the 2003 IRC. Believe this will help you.