The minimum roof pitch for shedding snow is around 30 or a 6 12 or 7 12 slope although this is not a definite as the material of your roof the direction of the snow and wind are some factors that can affect whether or not snow will slide as roofs of as little as 10 have been reported to shed snow.
Sloped roof snow load chart.
The sloped roof snow load p s shall be obtained by multiplying the flat roof snow load p f by the roof slope factor c s.
There are also factors such as deflection elasticity and wood species that come in to play.
R802 10 2 and designed according to the minimum requirements of asce 7 10.
If your roof is flat it is more likely to have snow load problems than if it is pitched.
In our case let s assume that our structure has a flat roof roof slope 5.
This rain on snow augmented design load applies only to the balanced load case and need not be used in combination with drift sliding unbalanced or partial loads.
Technically you should use the actual rafter length when adding up the weight of roofing materials.
The easiest way is to push a yardstick into the snow on the roof selecting an area that looks typical of the overall snow depth.
To do this i use conservative too heavy dead loads and full snow loads regardless of pitch.
If you live in the us our snow load calculator compares the total weight on your roof with the permissible load calculated according to the standards issued by the american society of civil engineers regarding the minimum design loads for buildings and other structures asce7 16.
On multiple factors including.
Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10.
Consult local building codes for snow load capacity and reference the span tables for joists and rafters published by the american wood council awc as a general rule roofs that have a high human occupancy rate should be framed with rafters every 16.
Ground snow load value.
I ignore the slope.
You need to use a snow load formula for flat roofs.
P s c s p f.
The flat roof snow load is calculated using formula 7 3 1.
Roof snow load is defined as the weight of snow on the roof surface used in design of the building structure ibc 2012.
Discount that actual snow loads may exceed them only that the risk of snow load induced failure is reduced to an acceptably low level.
First figure out how deep the snow is piled up there.
For locations where 0 pg 20 psf all roofs with a slope w 50 with w in ft shall have a 5 psf rain on snow surcharge.
Roofs of steeper pitches will likely.
It is determined based.
However in my practice i typically use the horizontal run of the roof for both types of load.
For dead loads you are correct.
