The importance of engineering the new retrofit framing system is hallmark to the overall project.
Retrofit installation pitched roof.
This system would consist of a base clip variable height post and a purlin system that would create the required positive pitch for a new metal roof panel system says chuck howard pe president of metal roof consultants inc cary n c.
In an un ventilated roof moist air is passed from the roof construction through the breather membrane out into a ventilated air space formed by counter battens.
These new roofs can be either low sloped less than 2 12 functional roofs or high pitched greater than 2 12 architectural roofs depending on the expectations of the building owner.
Once these and other pre installation steps are successfully completed the low slope roof retrofit can begin.
U value target u values normally achievable for the rafter level insulation of a pitched roof are between 0 20 0 16 w m2k depending on existing rafter depth and available space.