Analysis of an attic truss requires multiple load cases with multiple duration factors.
Attic dead load.
Boxes trunks suitcases etc.
The values for dead loads in table 3 2 are for commonly used materials and constructions in light frame residential buildings.
Storage space dead load of partitions 20 lbs.
If there s wall board covered ceiling suspended from the underside of that floor the dead load increases to about 10 pounds per square foot.
It is also an indeterminate structure with a non triangulated web area which interrupts the normal flow of forces thru the truss.
3 3 dead loads dead loads consist of the permanent construction material loads comprising the roof floor wall and foundation systems including claddings finishes and fixed equipment.
Most houses attics are built without flooring and are not designed to carry the heavy load of finished space.
Of floor area dead load of partitions 20 lbs.
In rare cases especially in new construction homes the attic may have been built unfinished with the correct flooring in place with the idea that the homeowner could later on finish the space.
A the top and bottom chord dead load.
The ceiling load may include items like drywall ducts recessed lights bathroom fans and attic insulation.
The dead load on a floor is determined by the materials used in the floor s construction.
Dead load of attic floor when floored 20 lbs.
C determine the total load and proper load duration.
Of floor area dead load on second floor 20 lbs.
This type of truss carries a combination of roof l r or s and floor l loading in addition to the standard top and bottom chord dead loads.
The truss shown below is known as an attic truss or a room in attic truss.
A typical wood frame floor covered with carpet or vinyl flooring has a dead load of about 8 pounds per square foot.
Unlike the trussed roof live load and dead load of the rafters and ceiling joists must be accounted for as separate systems.
Since it is possible to use the attic for storage the live load of the attic floor is set at 20 psf according to code.
As a result the live load dead load and distribution of forces are different.
Live loads are people and animals and tangentially the things used by people.
B the top chord live include snow load as a live load and bottom chord live load.
Dead load of first floor ceiling not plastered 10 lbs.
