reenforcing roof trusses

[foggysail]

I have had solar installed on four homes in California. Only one had roof trusses and the installer did not have to do any reinforcement. The other installs were traditional framing and I pulled two of the permits myself. The calculations were all about uplift since the weight of the panels was insignificant for my structures. In the designs I had control over I wanted to reduce penetrations so in those cases I used heavier rail that was able to have longer spans and I never encountered a situation where the framing members had to be reinforced. In those cases the roof rafters were at least 2x10 on 16 inch centers with spans of no more than 20 feet.

With trusses typically constructed of 2x4 on 24 inch centers I can imagine the engineering would in some cases require some additional reinforcement. I think a lot depends on wind and snow loads and other local jurisdiction requirements, In all my situations, snow and wind loads were not factors.
Are you adding new framing?

Ampster--- Most of California is relatively warm so most likely there were no snow loading worries..... is this correct for those installations you mentioned? Thx

[foggysail]

We have to do reinforcements in about 1 of 10 installs

Would you elaborate? I am trying to get a better understanding of an install because I am going to try doing my own----if I can get the permits.

Sure, I understand the structural advantage of trusses but not all homes here in Massachusetts have them. The reason for my question is asphalt shingles are HEAVY and code allows two layers. NOw I am not advocating installing panels ontop of two shingle layers, I only mentioned two shingle layers to show modern roofs should be able to carry a panel load. Consider 440 watt panels, one installed above the other with each having a weight of about 50 pounds each for a total of 100 of course for a vertical pair. But the widths of the panels are unimportant in my analysis because they are supported by a rail system. So the weight problem as I see it can be distributed by judicious placement of the rail supports.

Even with a good understanding, it will do me little good because I will be forced to get a structural engineer's report before I can get a permit. Thanks for taking the time to even read my post if you get this far.

[PVAndy]

This is a question to those that have done multiple installs. Have you had to do any reinforcement of the existing roof trusses before adding the new panels and framing?

We have to do reinforcements in about 1 of 10 installs

[Ampster]

This is a question to those that have done multiple installs. Have you had to do any reinforcement of the existing roof trusses before adding the new panels and framing?

I have had solar installed on four homes in California. Only one had roof trusses and the installer did not have to do any reinforcement. The other installs were traditional framing and I pulled two of the permits myself. The calculations were all about uplift since the weight of the panels was insignificant for my structures. In the designs I had control over I wanted to reduce penetrations so in those cases I used heavier rail that was able to have longer spans and I never encountered a situation where the framing members had to be reinforced. In those cases the roof rafters were at least 2x10 on 16 inch centers with spans of no more than 20 feet.

With trusses typically constructed of 2x4 on 24 inch centers I can imagine the engineering would in some cases require some additional reinforcement. I think a lot depends on wind and snow loads and other local jurisdiction requirements, In all my situations, snow and wind loads were not factors.
Are you adding new framing?

[Mike 134]

This is a question to those that have done multiple installs. Have you had to do any reinforcement of the existing roof trusses before adding the new panels and framing?