How far apart should roof purlins be?

When positioned, roof purlins should be spaced no further than 1.2 metres apart when using sheeting with a thickness of 0.7mm, and 1 metre when using 0.5mm sheeting. Exact requirements will vary, but as a rough guide, this is a good rule of thumb to follow.

How far apart are purlins on a metal roof?

The purlin are ultimately used to fasten the roof steel providing a diaphragm effect, along with the siding, when properly engineered and installed. Spacing is typically 24″ on center in low snow loads and is reduced based upon truss span and snow load.

How far apart can purlins be?

The maximum distance between purlins is five (5) feet on center. If your building site is in a region that is prone to heavy snow loads or high winds, then we may place your purlins closer together for added strength.

How is purlin spacing calculated?

To calculate the number of boards needed for purlins, divide the length of the purlin rows by the length of boards you are using (e.g. two boards of length eight feet for each 16 foot long purlin row).

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How far can 2×6 purlins span?

A 2×6 spaced 16 inches apart can span a maximum distance of 13 feet 5 inches when used as a rafter, 10 feet 9 inches when used as a joist, and 6 feet 11 inches when used as a deck beam to support joists with a 6-foot span.

Can you walk on a metal roof with purlins?

All metal roofing systems, especially steel roofing, can be walked on. Proper fall protection is always important when walking on any roof – never walk on a wet roof or one that has dew on it. Never walk on metal roofing panels before they are properly fastened down.

What size purlins do I need?

The sizes are as follows: A four-inch purlin can span 12 feet. A six-inch purlin can span 18 feet. An eight-inch purlin can span 25 feet.

How far apart should purlins be spaced on a pergola?

Purlins are usually spaced 8” OC.

How do I support my roof purlins?

Roof purlins are usually supported by 2×4 or 2×6 posts or struts. The posts will be spaced in four-foot distances for 2×4 purlins, while 2×6 purlins have them spaced at six feet apart. If the space between the posts is bigger than eight feet, a brace will be needed to avoid buckling.

What should be the distance between roof trusses?

Roof trusses should be 24” apart, on center. Trusses are allowed to be closer together, at either 12” or 16” on center, but building codes allow for 24” on center spacing without using heavier duty fasteners for truss to wall connections.

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How do you attach purlins to rafters?

Lay the first purlin at the ridge of the roof down to the chalk line beginning at either corner. Fasten the purlin with 16d common nails into each vertical rafter. Insert two equally spaced nails into the rafter. The rafters are generally spaced every 16 inches on center.

Is Z purlin stronger than C purlin?

Z purlins are much stronger than C purlins due to its continuous or overlapping capability. In this case, for the metal building with bigger roofing loading capacity.

What lengths do C purlins come in?

Cee Purlin lengths are cut to length from 6′-45′ in 1/8″ increments, though 20′ and 25′ are the most commonly chosen lengths.

How do you attach purlins to metal trusses?


Metal zee purlins should overlap on top of a truss. They should be placed on the outside of the truss clip with the bottom leg of the zee pointing toward the sidewall of the structure. The outermost truss clip will need to be adjusted for a vertical alignment.