Solar Ready Roof -- Existing Building

[Beginning-Bear]

Hi all, long time listener and first time caller.

I have a project in the Denver metro area and Colorado has recently adopted a "Colorado Model Electric Ready and Solar Ready Code" for all new buildings. The issue with my project is that it is an existing shell building that was designed in 2022 and likely built in 2023 so it was just before all of this was enacted (note: I do have the architectural and structural drawings for the shell). The initial structural scope was minor, provide some slab-pour back details for the ground floor (slab was previously left open in most of the building) and RTU reinforcement details along with the standard architectural and MEP finish out. The reviewer is now arguing that this constitutes a "major renovation" and is forcing the solar ready code upon us despite the scope of the project to essentially make the shell building inhabitable.

Roof framing is open web wood trusses bearing on steel beams at the exterior and interior grid lines and is a flat roof so any theoretical PV panels would have to be raised and the panels angled. As far as my understanding, the theoretical PV panels could be "ballasted," i.e. use concrete blocks to weigh them down or to penetrate the roof deck with anchors into the roof framing below. Neither are very appealing as the open web wood trusses are unlikely to have much additional capacity (note: I do not have the shop drawings) and the panel orientation is likely to be perpendicular (typical to face panels in the southern direction) to the framing below (running east-west) and I'm worried any horizontal load transmitted to them would cause them to roll.

Has anyone encountered a similar situation with the code reviewer requiring solar ready framing on an existing roof? Or how have you handled it when designing new flat roofs? I've done some work in the past for placing PV panels on carports, ground-mounted systems, and parallel to a sloped roof but this is a first for me and I'm interested to see how others have interpreted these (or similar) provisions.

The architect and I are pushing back against the reviewer, but they are obtuse and don't quite understand the implications of what they're enforcing. (Those who cannot do, review).

 

[ChorasDen]

What is your involvement here? This project was permitted in the 2022-2023 timeframe and constructed in 2023, surely the set of plans reviewed and approved by the AHJ in 2023 is all you need?

 

[Beginning-Bear]

What is your involvement here? This project was permitted in the 2022-2023 timeframe and constructed in 2023, surely the set of plans reviewed and approved by the AHJ in 2023 is all you need?

Involvement: structural engineer for the TI finish out of the shell building. As mentioned we have the shell building drawings but because it was permitted before the solar ready code was enacted, the city reviewer is pushing this on us.

Asking what needs to be shown on my drawings to indicate that the roof is either: a) okay for the additional "solar ready" PV panel loads or b) what kind of strengthening is required for the potential PV panels and associated uplift/horizontal wind loads and/or ballast weight on the roof. Expectations are unclear in the Solar Ready Code and this is my first time bumping into it.

 

[Aesur]

I hate to say it, but it's common that many engineers who do "solar ready" just throw in dead loading for a system, and don't even look at wind, basically relying on the fact that technically it can take a flat system, close to the roof with proper gaps to not increase wind loading on the structure. Technically by code it's solar ready, just not solar ready for an efficient system. If you want to make solar ready for an efficient system, then you have to know what solar system is going on there to do so and not just wing it unless you want to go very conservative.

Now that being said, I have never encountered such pushback from a plan reviewer, and I would dig into the IEBC to classify properly as a starting point and if you find that it is a major revision, then your hands may be tied and the only option is to get an exemption which would probably require a talk with the building official instead of the plan reviewer. If you find it's not a major revision that requires bring to latest code request the reviewer to show you the code section requiring it be brought up to code.

Note that there may be other building issues if it's the latest IBC, including energy efficiency changes and closed shafts for the new refrigerant for mechanical.

 

[azcats]

The definition of 'major renovation' can't just be up to one yahoo, can it?

My fight would start there. Probably have to go over their head to someone reasonable. By their definition, any large TI would require structural modifications to the roof.

I guess the .gov has forced these things on people before as with seismic retrofits - at least there's life safety involved there.

 

[Beginning-Bear]

I hate to say it, but it's common that many engineers who do "solar ready" just throw in dead loading for a system, and don't even look at wind, basically relying on the fact that technically it can take a flat system, close to the roof with proper gaps to not increase wind loading on the structure. Technically by code it's solar ready, just not solar ready for an efficient system. If you want to make solar ready for an efficient system, then you have to know what solar system is going on there to do so and not just wing it unless you want to go very conservative.

Now that being said, I have never encountered such pushback from a plan reviewer, and I would dig into the IEBC to classify properly as a starting point and if you find that it is a major revision, then your hands may be tied and the only option is to get an exemption which would probably require a talk with the building official instead of the plan reviewer. If you find it's not a major revision that requires bring to latest code request the reviewer to show you the code section requiring it be brought up to code.

Note that there may be other building issues if it's the latest IBC, including energy efficiency changes and closed shafts for the new refrigerant for mechanical.

Thanks, this is kind of what I wanted to know. It seems like a chicken and egg situation (what comes first) with the panels since we aren't actually installing any so it's impossible to know exactly what type of system would potentially be installed and the angle of the panels have a big impact on the wind loading.

My understanding is that because the revision incorporates > 50% of the building floor space, they classify it as Tier 3 revision per the IEBC. Which they've taken to define as "major." I'm trying to argue it's a Tier 1 revision since nearly all of the TI is the interior fit out to make the building habitable + two RTUs in a mechanical zone.

The definition of 'major renovation' can't just be up to one yahoo, can it?

My fight would start there. Probably have to go over their head to someone reasonable. By their definition, any large TI would require structural modifications to the roof.

I guess the .gov has forced these things on people before as with seismic retrofits - at least there's life safety involved there.

Yes, this is my main problem with many plans reviewers and building officials. I hinted to the architect that we could play the "project owner decides to take their business to another city card" because it's silly to retrofit approximately 40% of a brand new roof.