Once your purlins have been fitted and a supporting framework has been created you should look to carry out an inspection before you continue work.
How to support roof purlins.
Lay the first purlin at the ridge.
Snap a chalk line horizontally across the roof two feet down from the top.
Using a combination of rafters and purlins is common.
Purlins can be fixed to rafters and all joins and laps should be supported by a rafter.
Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed for installation.
Here are several useful tips for purlin installations.
Double them up in valleys.
How to support roof purlins.
With rafters it runs in perpendicular from the walls to the ridge while with purlins it runs to the ridge in parallel.
The support system for the roof is comprised of ridgepole and rafters or purlins.
Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and or the building walls steel beams etc.
The use of purlins as opposed to closely spaced rafters is common in pre engineered metal building systems and both the ancient post and beam and newer pole building timber frame construction methodologies.
Have them installed by following the edges or sides of your roof.
In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof.