Pole Barn Roof Purlin Spacing

With this design change roof trusses could be placed 12 feet apart making it possible for roofs to support the loads to which they would be subjected.

Pole barn roof purlin spacing.

Nails trim basic plans. I am wanting to make it 14 deep and 22 wide with no center post in the 14 span. The purlins are nailed to the trusses with two 20d galvanized ring shank nails. I am building a shed roof pole barn for donkeys.

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal. I ve had roof truss manufacturers try to convince me it is impossible to place wood trusses at spacings of over every 4 feet. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig. Vinyl siding trim on 7 16 sheathing and house wrap additional 2x4 vertical nailer 4 on center for 4x8 sheathing painted steel siding trim w matching screws 29 ga.

Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes. Our roof rafter calculator tools are handy for calculating the number of rafters needed rafter length calculator lineal feet of rafter board feed in ridge and sub facia and the total board feet in the roof. Many post frame or pole barn construction use 8 foot spacing between trusses. I am wondering if a 2 x 6 x 16 rafters 2 oc will work.

5 x ps roof snow load adjusted for slope factors x purlin spacing x purlin span 4. The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. Purlins are usually spaced 24 inches on center in low snow loads but they are put closer together if snow loads are higher. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry.

Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. This is typically done with 2x4s. Here is the formula for calculation of a roof purlin. It will have a metal roof over purlins.

The pt posts are 6 x 6 spaced either 6 or 8 apart on the high and low load bearing side walls. 384 x e modulus of elasticity for the lumber being used x i moment of inertia for the lumber size plugging in the variables. 5 x 18 98 psf 144 has to be divided by 144 to give psi x 24 x 70 5 4 384 x 1 400 000 x 0 984 0 795. Cos of live load dead load x cos of the purlin spacing x purlin span squared 8 x sm section modulus of the member x duration of load 1 15 in areas with snowfall x cr repetitive member factor of 1 15 where members are 24 on center or less fb fiberstress required.

The most common method of installing purlins in a pole barn is to lay them flat. It was perkins who pioneered roof purlins being placed on edge. Fyi we run purlins on 3 5 feet on center depending on size of purlin. Installation of pole barn purlins.