Kiln dried softwood is recommended for purlins or decking pine fir hemlock and spruce.
Purlin spacing for corrugated metal roofing.
Without a set of blueprints with a pe s seal you have no option but to follow the inspectors gig.
Purlin spacing should suit the end laps required for the size of sheet to be used.
Be sure the larger edge is laid so that the small edge of the next panel will overlap it.
These panels can cost more to install that a traditional roof but in the long run are often a better value.
When framing the roof the spacing for roof trusses should not exceed 24 inches 61 cm and purlins should not exceed 36 inches 91 cm apart.
For the lighter material such as lightweight aluminum the common spacing length is 4 inches of clear gap.
Purlin spacing for metal roofing.
Corrugated metal panels often called tin because in the past such panels were sometimes made of tin are typically steel or aluminum sheets that are used as a roofing material.
Z purlins are connected to the rafters using cleats.
Align the first metal roofing panel so that it overlaps the edging by 1 2 to 3 4 of an inch and is square to the roof line.
The overlaps ends and sides depends upon the sloop of the roof see below.
Purlins are non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern.
The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.
When using purlins fabral recommends a maximum spacing of 24 on center note that 5v requires solid decking.
For heavier material such as gage steel the metal roof purlins spacing length could go up to 4 feet.
There will be four screws per screw line placed in the high of the corrugated panel.
Minimum recommended purlin size is 4 x 2 50mm x 100mm in timber or z140mm x 1 6mm in steel.
The diagram above is a typical 37 wide panel and the spacing works out perfectly.
However sometimes corrugated sheets are 39 wide instead of 37 wide.
All purlin joints must be supported by a rafter.
Purlins provide horizontal support for the sheets and form part of the framework for the building.
Corrugations should run in a straight line between the highest and lowest points and at a right angle to the purlins the intermediate supports.
Purlin spacing is dependent on profile of the metal and gauge plus snow and wind load plus what the rafters are designed to carry.
You can use both types of corrugated roofing together creating panels that will allow light to come through as with a clear or white fiberglass corrugated panel known as a skylight.
Fyi we run purlins on 3 5 feet on center depending on size of purlin.
Corrugated sheet roofing material is widely available and easy to use.
We do recommend it however.
The screws are spaced out so that every third corrugation has a screw.
Do all roofing projects require purlins.
