If you have a stick frame roof there are a few basic techniques that you can use to strengthen your rafters.
Reinforcing roof truss frames under load.
Without altering the roof structure of an industrial boiler plant a long span steel truss frame was modified in place to support heavier loads.
Space them four inches apart along the edges and six inches apart in the middle of the plywood sheathing.
If dead loads must be hung from trusses then extra support can be provided by installing support beams perpendicular to the trusses reducing the span of the bottom chords and increasing their ability to carry the weight load.
These are usually accomplished during a complete re roofing.
Reinforcing roof truss frames under load.
The owners of an industrial boiler plant in the northeast were required to reduce particulate emission levels from coal fired boilers.
Strengthening existing roof rafters is a difficult process that often requires professional help.
Snow increases the overall weight of your roof adding to the forces acting on your rafters.
Connect roof sheathing to the roof framing with ten penny weight common or eight penny weight ring shank nails.
Compromised trusses can lead to severe structural problems such as bowing exterior walls sagging ridge lines and roof collapse.
Replacement of a two field electrostatic precipitator.
Reinforce your roof a properly constructed roof in areas subject to high winds has trusses attached to walls with hurricane tiedowns properly nailed sheathing and heavy duty shingles.