Paolo formichi university of pisa italy.
Snow loading flat roof uk.
The snow load that is applied to our structure is not the ground snow load but in most cases the flat roof snow load.
Wind snow and rain.
The scope of bs en 1991 1 3 is limited to snow loads only c in accordance with clause 3 3 2 1 of bs en 1991 1 1 roofs of buildings particularly domestic roofs where the allowed imposed loads cover maintenance only imposed loads need not be considered to act simultaneously with snow loads and or wind actions.
The uniformly distributed snow loading on the roof is obtained by multiplying the ground snow load by the appropriate snow load shape coefficient see section 5 3 of bs en 1991 1 3 and annex b of bs en1991 1 3.
Other considerations for sloped roofs can be found throughout chapter 7 of asce 7 10.
The snow load on the roof is derived from the snow load on the ground multiplying by appropriate conversion factors shape thermal and exposure coefficients.
For roofs that are flat and with ground snow loads lower than 20 pounds per square foot the roof snow load is equal to 70 of the product of the exposure thermal and importance factors and the ground snow load.
Brussels 18 20 february 2008 dissemination of information workshop 18.
For ground snow loads greater than 20 pounds per square foot the roof load is equal to 70 of the product of the exposure thermal and importance factors the ground snow load and 20 pounds.
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.
Use this same calculation to find the total weight of snow on a flat roof.
A person needing to access the roof in order to repair items.
Step 4 determine the flat roof snow load.
For example using a 25 by 20 metre garden.
500 times 1 25 yields 625 kg 1 378 lb of snow.
Estimate the total weight of snow in your garden by multiplying the size of the area in square metres by the snow load.
In our case let s assume that our structure has a flat roof roof slope 5.
The loads weights to be supported are from various sources.
However when heavy snowfalls do occur there are often reports of damage to buildings in particular collapses of roofs and their supporting structures.
Flat roof structure.
Dead loads from the self weight of the roof construction.
The flat roof snow load is calculated using formula 7 3 1.
Flat roofs shall be designed to carry all imposed and dead loads acting on the structure of the roof.
Environmental loads such as snow water and wind loads should be calculated in accordance with bs en 1991.
This would include tiles battens felt insulation etc.
