The support system for the roof is comprised of ridgepole and rafters or purlins.
How to support roof purlins.
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.
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.
Placing the roof along the perimeter of your roof is.
With rafters it runs in perpendicular from the walls to the ridge while with purlins it runs to the ridge in parallel.
In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof.
Double them up in valleys.
Using a combination of rafters and purlins is common.
How to support roof purlins.
How to install metal roof purlins.
Lay the first purlin at the ridge.
Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed for installation.
Due to the angle that created in the valley it is necessary to double the purlins.
Have them installed by following the edges or sides of your roof.