Pole Barn Roof Purlin Spacing

Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal.

Pole barn roof purlin spacing.

I am wanting to make it 14 deep and 22 wide with no center post in the 14 span. The pt posts are 6 x 6 spaced either 6 or 8 apart on the high and low load bearing side walls. Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes. Investigators have found that post frame structures fare surprisingly well in the tornado prone areas of the central united states.

The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. I ve had roof truss manufacturers try to convince me it is impossible to place wood trusses at spacings of over every 4 feet. This is typically done with 2x4s. 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.

Spacing is typically 24 on center in low snow loads and is reduced based upon truss span and snow load. It was perkins who pioneered roof purlins being placed on edge. 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. 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. Many post frame or pole barn construction use 8 foot spacing between trusses. Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig. Nails trim basic plans.

Since the weather is a critical factor how well do these hold up in the severest of weather conditions. Here is the formula for calculation of a roof purlin. It will have a metal roof over purlins. 384 x e modulus of elasticity for the lumber being used x i moment of inertia for the lumber size plugging in the variables.

I am building a shed roof pole barn for donkeys. Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry. Truss spacing roof purlins and roof sheathing is listed below with the roofing finish options. Purlins are usually spaced 24 inches on center in low snow loads but they are put closer together if snow loads are higher.

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. Fyi we run purlins on 3 5 feet on center depending on size of purlin. Installation of pole barn purlins. The purlins are nailed to the trusses with two 20d galvanized ring shank nails.