Roof Live Load Vs Dead Load

The dead loads are permanent loads which result from the weight of the structure itself or from other permanent attachments for example drywall roof sheathing and weight of the truss.

Roof live load vs dead load.

Victor staley a building official in the town of brewster mass responds. V earthquake loads dead loads. Unlike the trussed roof live load and dead load of the rafters and ceiling joists must be accounted for as separate systems. The might of the dead load or lack thereof often defines how much live load it can handle.

Af pa s appendix a lists a variety of live and dead load combinations for floors ceilings and rafters. Dead loads depends upon the unit weight of the material. L r l o r 1 r 2. 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.

For example appendix a indicates that one type of clay tile roof system has a live load value of 20 psf and a dead load value of 15 psf. Roof live load reduction. All loads are typically categorized into two types live and dead. Because live loads depend on structural strength knowledge of the exact planned use of the building is critical.

Ground snow load might seem somewhat confusing until you read the basic premise that is identified in irc section r301 6 which states. Dead loads are due to self weight of the structure. The roof shall be designed for the live load indicated in table r301 6 or the snow load indicated. Where l r shall not be less than 12 psf and not more than 20 psf.

On a roof with a slope greater than 4 to 12 the live load limit is typically adjusted downward from 20 psf to 15 psf to allow for the relatively greater dead load on the steeper roof. It is simply listed. The metal building company does provide live load reactions but having inquired of this in the past i ve been informed that the live loads unless specifically stated otherwise refer to roof live loads. Where d is floor dead load.

Canpro the metal building company did not break the mezzanine loads into dead live. This issue of live load vs. Roof live load may be reduced by the following equation. And also the permanent fixtures present in the structure.

As a result the live load dead load and distribution of forces are different. Reinforced concrete creates the heaviest dead loads but also supports the most weight with its tremendous compressive strength.