Formula For Determining Deck Load With A Roof Over

Technically you should use the actual rafter length when adding up the weight of roofing materials.

Formula for determining deck load with a roof over. Remember these loads are distributed uniformly over the entire surface of the roof. However in my practice i typically use the horizontal run of the roof for both types of load. Deck beams and joists go hand in hand as the framing materials for your deck. This is all of the natural stresses imposed upon a roof such as snow loads rain loads and wind loads.

If an example roof is 10 feet by 20 feet the total area is 200 square feet. To determine the maximum load capacity of your deck start by calculating its total area and multiply by 50 psf. The total load for each tributary area is then divided by the area of each footing in order to determine the load psf imposed on the soil. This number is then multiplied by 50 which is the 40 psf live load 10 psf dead load mentioned earlier.

Multiply the load per square foot by the total area of the roof. This calculator determines the size of each tributary area of your deck. This number represents the total load that your roof must carry. 7 feet the distance between the ledger and the beam divided by 2 half of the load multiplied by 12 the length of the deck multiplied by 50 psf the load which equals 2 100 pounds.

This is the amount of weight that must be supported by the pier. Default is 50 psf which you can change. To determine the load of a deck pier you must take half the length of the joist span multiplied he length of the beam span measured from pier to pier. Multiplied by 40 pounds per square foot equals 8 000 pounds.

Total number of boards dsa sbc x 1 1 calculate how much deck material you need for your new deck. The exterior wall and the headers within will carry all loads from the mid point of the house between the supporting walls to the outside of the house including the roof overhang. Your beams will need to bear the load of not only your decking materials but additional components of the frame itself. The distance in this case is 12 ft 2 ft 14 ft.

It then determines the total load from each tributary area based on the design load of your deck. If you drove a dump truck over it yes this would throw all our calculations out the window. So a 100 sqft deck would be designed to support 5000 lbs. For dead loads you are correct.

Determine the transient load of the roof. To do this i use conservative too heavy dead loads and full snow loads regardless of pitch. If you re brand new to deck installation follow the steps below to ensure you buy the correct quantity of all materials.