One of them is that flat roofs leak more easily than pitched ones.
Flat roof for snow load.
First figure out how deep the snow is piled up there.
Pf is flat roof snow load if as a consumer your concern is snowfall and you want to upgrade the ability of your building to carry it this is the value to increase.
Express the result in feet rather than inches.
Online snow load calculator for buildings with flat or low slope roofs for balanced snow drift and rain on snow surcharge loadings calculator asce 7 05 for structural engineers construction professionals and building planners.
Lets assume our project is in madison wisconsin and we have already calculated our balanced roof snow load here.
If you have any concerns as you are determining your flat roof snow load consult with a structural engineer or roofing specialist.
When discussing snow load with anyone it is crucial to have a clear understanding as to if the load is a ground or flat roof snow load.
The flat roof snow load is calculated using formula 7 3 1.
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.
For example 18 inches would be 1 5 feet.
Minimum flat roof snow load values.
Asce 7 05 equation 7 1 assumes that the snow load results from multiple events.
This is all of the natural stresses imposed upon a roof such as snow loads rain loads and wind loads.
You need to use a snow load formula for flat roofs.
In our case let s assume that our structure has a flat roof roof slope 5.
From our example our ground load and flat roof snow load were found to be 30 psf and 21 psf respectively.
Provisions on how to calculate the snow drift surcharge for structures can be found in section 7 8 of asce 7 10.
As a result equation 7 1 which accounts for loss between events will result in a non conservative value.
Determine the transient load of the roof.
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.
Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10.
There are a few common misconceptions regarding flat roofs that are stubbornly persistent.
The snow load that is applied to our structure is not the ground snow load but in most cases the flat roof snow load.
In regions with relatively low snow load values the load from a single event may result in the peak loading.
